vendex and Athletic-Injuries

Anterior cruciate ligament (ACL) reconstruction has a detrimental impact on athletic performance. Despite rehabilitation guidelines and criterion-based progressions to ensure safe restoration of fundamental physical capacities and maladaptive movement strategies, residual deficits in maximal strength, rate of force development (RFD), power and reactive strength are commonly reported. These combined with associated compensatory inter and intra-limb strategies increase the risk of re-injury.. The aim of this article is to examine the relationships between fundamental physical capacities and biomechanical variables during dynamic movement tasks.. Narrative review.. The available data suggests that quadriceps strength and rate of torque development, explain a moderate portion of the variance in aberrant kinetic and kinematic strategies commonly detected in ACL reconstructed cohorts in the later stages of rehabilitation and RTS CONCLUSION: The available data suggests that quadriceps strength and rate of torque development, explain a moderate portion of the variance in aberrant kinetic and kinematic strategies commonly detected in ACL reconstructed cohorts in the later stages of rehabilitation and RTS.

Topics: Anterior Cruciate Ligament Injuries; Anterior Cruciate Ligament Reconstruction; Athletic Injuries; Biomechanical Phenomena; Humans; Movement; Muscle Strength; Quadriceps Muscle; Return to Sport; Torque

Hamstring injuries are highly prevalent in many running-based sports, and predominantly affect the long head of biceps femoris. Re-injury rates are also high and together lead to considerable time lost from sport. However, the mechanisms for hamstring injury during high-speed running are still not fully understood. Therefore, the aim of this review was to summarize the current literature describing hamstring musculotendon mechanics and electromyography activity during high-speed running, and how they may relate to injury risk. The large eccentric contraction, characterized by peak musculotendon strain and negative work during late swing phase is widely suggested to be potentially injurious. However, it is also argued that high hamstring loads resulting from large joint torques and ground reaction forces during early stance may cause injury. While direct evidence is still lacking, the majority of the literature suggests that the most likely timing of injury is the late swing phase. Future research should aim to prospectively examine the relationship between hamstring musculotendon dynamics and hamstring injury.

Topics: Athletic Injuries; Biomechanical Phenomena; Electromyography; Hamstring Muscles; Hip; Humans; Knee; Running; Tendons; Torque

To examine the value of isokinetic strength assessment for predicting risk of hamstring strain injury, and to direct future research into hamstring strain injuries.. Systematic review.. Database searches for Medline, CINAHL, Embase, AMED, AUSPORT, SPORTDiscus, PEDro and Cochrane Library from inception to April 2017. Manual reference checks, ahead-of-press and citation tracking.. Prospective studies evaluating isokinetic hamstrings, quadriceps and hip extensor strength testing as a risk factor for occurrence of hamstring muscle strain.. Independent search result screening. Risk of bias assessment by independent reviewers using Quality in Prognosis Studies tool. Best evidence synthesis and meta-analyses of standardised mean difference (SMD).. Twelve studies were included, capturing 508 hamstring strain injuries in 2912 athletes. Isokinetic knee flexor, knee extensor and hip extensor outputs were examined at angular velocities ranging 30-300°/s, concentric or eccentric, and relative (Nm/kg) or absolute (Nm) measures. Strength ratios ranged between 30°/s and 300°/s. Meta-analyses revealed a small, significant predictive effect for absolute (SMD=-0.16, P=0.04, 95% CI -0.31 to -0.01) and relative (SMD=-0.17, P=0.03, 95% CI -0.33 to -0.014) eccentric knee flexor strength (60°/s). No other testing speed or strength ratio showed statistical association. Best evidence synthesis found over half of all variables had moderate or strong evidence for no association with future hamstring injury.. Despite an isolated finding for eccentric knee flexor strength at slow speeds, the role and application of isokinetic assessment for predicting hamstring strain risk should be reconsidered, particularly given costs and specialised training required.

Topics: Athletic Injuries; Hamstring Muscles; Humans; Muscle Strength; Predictive Value of Tests; Sprains and Strains; Torque

Hamstring strain injuries are the predominant injury in many sports, costing athletes and clubs a significant financial and performance burden; therefore, the ability to identify and intervene with individuals who are considered at high risk of injury is important. One measure that has grown in popularity as an outcome variable following hamstring intervention/prevention studies and rehabilitation is the angle of peak knee flexor torque. This current opinion article will firstly introduce the measure and the processes behind it. Second, the article will summarise how the angle of peak knee flexor torque has been suggested to measure hamstring strain injury risk. Finally, the numerous limitations will be presented and the article will outline how these limitations may influence the usefulness of the angle of peak knee flexor torque measure. These include the lack of muscle specificity, the common concentric contraction mode of assessment, reliability of the measure, various neural contributions (such as rate of force development and neuromuscular inhibition), as well as the lack of prospective data showing any predictive value in the measure.

Topics: Athletic Injuries; Electric Stimulation; Humans; Isometric Contraction; Knee Joint; Leg Injuries; Muscle Contraction; Muscle, Skeletal; Recurrence; Risk Factors; Sprains and Strains; Torque

Hamstring strain injuries are amongst the most common and problematic injuries in a wide range of sports that involve high speed running. The comparatively high rate of hamstring injury recurrence is arguably the most concerning aspect of these injuries. A number of modifiable and nonmodifiable risk factors are proposed to predispose athletes to hamstring strains. Potentially, the persistence of risk factors and the development of maladaptations following injury may explain injury recurrence. Here, the role of neuromuscular inhibition following injury is discussed as a potential mechanism for several maladaptations associated with hamstring re-injury. These maladaptations include eccentric hamstring weakness, selective hamstring atrophy and shifts in the knee flexor torque-joint angle relationship. Current evidence indicates that athletes return to competition after hamstring injury having developed maladaptations that predispose them to further injury. When rehabilitating athletes to return to competition following hamstring strain injury, the role of neuromuscular inhibition in re-injury should be considered.

Topics: Athletic Injuries; Cicatrix; Humans; Knee Joint; Muscle Weakness; Muscle, Skeletal; Muscular Atrophy; Neural Inhibition; Recurrence; Risk Factors; Sprains and Strains; Torque

The evolution of synthetic playing surfaces began in the 1960s and has had an impact on field use, shoe-surface dynamics, and the incidence of sports-related injuries. Modern third-generation turfs are being installed in recreational facilities and professional stadiums worldwide. Currently, > two-thirds of National Football League teams, > 100 National Collegiate Athletic Association Division I football teams, and > 1000 high schools in the United States have installed synthetic playing surfaces. Those in favor of such playing surfaces note their unique combination of versatility and durability; they can be used in both ideal and inclement weather conditions. However, the more widespread installation and use of these surfaces have raised questions and concerns regarding the impact of artificial turf on the type and severity of sports-related injuries. There appears to be no question that the shoe-surface interface has a significant impact on such injuries. Independent variables such as weather conditions, contact versus noncontact sport, shoe design, and field wear complicate many of the results reported in the literature, thereby preventing an accurate assessment of the true risk(s) associated with certain shoe-surface combinations. Historically, studies suggest that artificial turf is associated with a higher incidence of injury. Furthermore, reliable biomechanical data suggest that both the torque and strain experienced by lower extremity joints generated by artificial surfaces may be more than those generated by natural grass fields. Recent data from the National Football League support this theory and suggest that elite athletes may sustain more injuries, even when playing on the newer artificial surfaces. By contrast, some reports based on data collected from lower-level athletes suggest that artificial turf may protect against injury. This review discusses the history of artificial surfaces, the biomechanics of the shoe-surface interface, and some common turf-related lower extremity injuries.

Topics: Athletic Injuries; Biomechanical Phenomena; Friction; Humans; Leg Injuries; Rotation; Shoes; Surface Properties; Torque

Topics: Anterior Cruciate Ligament; Anterior Cruciate Ligament Injuries; Athletic Injuries; Basketball; Biomechanical Phenomena; Female; Humans; Joint Instability; Knee Injuries; Lower Extremity; Male; Muscle Fatigue; Muscle, Skeletal; Sex Factors; Soccer; Torque

Knee injuries are common in sports activities. Understanding the mechanisms of injury allows for better treatment of these injuries and for the development of effective prevention programmes. Tibial torque and knee flexion angle have been associated with several mechanisms of injury in the knee. This article focuses on the injury to the anterior cruciate ligament (ACL), the posterior cruciate ligament (PCL) and the meniscus of the knee as they relate to knee flexion angle and tibial torque. Hyperflexion and hyperextension with the application of tibial torque have both been implicated in the mechanism of ACL injury. A combination of anterior tibial force and internal tibial torque near full extension puts the ACL at high risk for injury. Hyperflexion also increases ACL force; however, in this position, internal and external tibial torque only minimally increase ACL force. Several successful prevention programmes have been based on these biomechanical factors. Injury to the PCL typically occurs in a flexed or hyperflexed knee position. The effects of application of a tibial torque, both internally and externally, remains controversial. Biomechanical studies have shown an increase in PCL force with knee flexion and the application of internal tibial torque, while others have shown that PCL-deficient knees have greater external tibial rotation. The meniscus must endure greater compressive loads at higher flexion angles of the knee and, as a result, are more prone to injury in these positions. In addition, ACL deficiency puts the meniscus at greater risk for injury. Reducing the forces on the ACL, PCL and meniscus during athletic activity through training, the use of appropriate equipment and safe surfaces will help to reduce injury to these structures.

Topics: Anterior Cruciate Ligament Injuries; Athletic Injuries; Biomechanical Phenomena; Humans; Knee Injuries; Knee Joint; Posterior Cruciate Ligament; Range of Motion, Articular; Tibia; Tibial Meniscus Injuries; Torque

Exercise-induced muscle damage is a well documented phenomenon particularly resulting from eccentric exercise. When eccentric exercise is unaccustomed or is performed with an increased intensity or duration, the symptoms associated with muscle damage are a common outcome and are particularly associated with participation in athletic activity. Muscle damage results in an immediate and prolonged reduction in muscle function, most notably a reduction in force-generating capacity, which has been quantified in human studies through isometric and dynamic isokinetic testing modalities. Investigations of the torque-angular velocity relationship have failed to reveal a consistent pattern of change, with inconsistent reports of functional change being dependent on the muscle action and/or angular velocity of movement. The consequences of damage on dynamic, multi-joint, sport-specific movements would appear more pertinent with regard to athletic performance, but this aspect of muscle function has been studied less often. Reductions in the ability to generate power output during single-joint movements as well as during cycling and vertical jump movements have been documented. In addition, muscle damage has been observed to increase the physiological demand of endurance exercise and to increase thermal strain during exercise in the heat. The aims of this review are to summarise the functional decrements associated with exercise-induced muscle damage, relate these decrements to theoretical views regarding underlying mechanisms (i.e. sarcomere disruption, impaired excitation-contraction coupling, preferential fibre type damage, and impaired muscle metabolism), and finally to discuss the potential impact of muscle damage on athletic performance.

Topics: Action Potentials; Athletic Injuries; Cumulative Trauma Disorders; Exercise; Exercise Tolerance; Humans; Motor Neurons; Muscle Contraction; Muscle Fatigue; Muscle Fibers, Fast-Twitch; Muscle, Skeletal; Torque

There is growing evidence that isokinetic muscle strength, is one of the most common testing method why muscle strength is thought to be a major factor in athletic success and rehabilitation. A lot of publications during the last 20 years concerned the peak torque, the concentric ratio flexor/extensor, with comparison between males and females, sport specialties, young and old people. Isokinetic is also used for evaluation of knee disorders. The results are very useful after knee ligament surgery, less for femoro-patellar disorders and arthrosis. More recently some authors proposed the functional concept (eccentric flexors/concentric extensors ratio) as a predictive method for preventive muscle injuries or ACL lesions. They demonstrated more discomfort after muscle disorders with isokinetic eccentric testing, and proposed rehabilitation programs for prevention. However apart from a few situations, isokinetic testing does not fully predict functional measurements. It must be used with other techniques of evaluation (clinical methods and imagery).

Topics: Age Factors; Anterior Cruciate Ligament; Anterior Cruciate Ligament Injuries; Athletic Injuries; Biomechanical Phenomena; Female; Humans; Knee; Knee Injuries; Leg; Male; Muscle, Skeletal; Prognosis; Reference Values; Sex Factors; Torque

Proper throwing mechanics may enable an athlete to achieve maximum performance with minimum chance of injury. While quantifiable differences do exist in proper mechanics for various sports, certain similarities are found in all overhand throws. One essential property is the utilisation of a kinetic chain to generate and transfer energy from the larger body parts to the smaller, more injury-prone upper extremity. This kinetic chain in throwing includes the following sequence of motions: stride, pelvis rotation, upper torso rotation, elbow extension, shoulder internal rotation and wrist flexion. As each joint rotates forward, the subsequent joint completes its rotation back into a cocked position, allowing the connecting segments and musculature to be stretched and eccentrically loaded. Most notable is the external rotation of the shoulder, which reaches a maximum value of approximately 180 degrees. This biomechanical measurement is a combination of true glenohumeral rotation, trunk hyperextension and scapulothoracic motion. Near the time of maximum shoulder external rotation (ERmax), shoulder and elbow musculature eccentrically contract to produce shoulder internal rotation torque and elbow varus torque. Both the shoulder and the elbow are susceptible to injury at this position. At ball release, significant energy and momentum have been transferred to the ball and throwing arm. After ball release, a kinetic chain is used to decelerate the rapidly moving arm with the entire body. Shoulder and elbow muscles produce large compressive forces to resist joint distraction. Both joints are susceptible to injury during arm deceleration.

Topics: Arm; Athletic Injuries; Biomechanical Phenomena; Elbow Injuries; Elbow Joint; Energy Transfer; Female; Humans; Kinetics; Leg; Male; Muscle, Skeletal; Pelvis; Rotation; Shoulder Injuries; Shoulder Joint; Sports; Thorax; Torque; Wrist Joint

We examined the effects of a 12-week program of Nordic hamstring exercises (NHE), administered before or after football training, upon eccentric hamstring strength, muscle activity, and architectural adaptations. Amateur soccer players were randomized into three groups. The control group (CON; n=11) undertook core stability exercises, whereas a periodized NHE program was delivered either before (NHE

Topics: Adult; Athletic Injuries; Electromyography; Hamstring Muscles; Humans; Male; Muscle Strength; Physical Conditioning, Human; Resistance Training; Soccer; Torque; Young Adult

The muscular function restoration related to the type of physical rehabilitation followed after anterior cruciate ligament reconstruction (ACLR) using autologous hamstring tendon graft in terms of strength and cross-sectional area (CSA) remain controversial.. To analyze the CSA and force output of quadriceps and hamstring muscles in subjects following either an Objective Criteria-Based Rehabilitation (OCBR) algorithm or the usual care (UCR) for ACL rehabilitation in Spain, before and 1 year after undergoing an ACLR.. Longitudinal clinical double-blinded randomized controlled trial.. Sports-medicine research center.. 40 recreational athletes (30 male, 10 female [24 ± 6.9 y, 176.55 ± 6.6 cm, 73.58 ± 12.3 kg]).. Both groups conducted differentiated rehabilitation procedures after ACLR. Those belonging to OCBR group were guided in their recovery according to the current evidence-based principles. UCR group followed the national conventional approach for ACL rehabilitation.. Concentric isokinetic knee joint flexor-extension torque assessments at 180°/s and Magnetic Resonance Imaging (MRI) evaluations were performed before and 12 months after ACLR. Anatomical muscle CSA (mm2) was assessed, in Quadriceps, Biceps femoris, Semitendinous, Semimembranosus, and Gracilis muscles at 50% and 70% femur length.. Reduced muscle CSA was observed in both treatment groups for Semitendinosus and Gracilis 1 year after ACLR. At 1-year follow-up, subjects allocated to the OCBR demonstrated greater knee flexor and extensor peak torque values in their reconstructed limbs in comparison with patients treated by UCR.. Objective atrophy of Semitendinosus and Gracilis muscles related to surgical ACLR was found to persist in both rehabilitation groups. However, OCBR after ACLR lead to substantial gains on maximal knee flexor strength and ensured more symmetrical anterior-posterior laxity levels at the knee joint.

Topics: Adolescent; Adult; Anterior Cruciate Ligament Injuries; Anterior Cruciate Ligament Reconstruction; Athletic Injuries; Double-Blind Method; Female; Hamstring Muscles; Hamstring Tendons; Humans; Knee Joint; Longitudinal Studies; Male; Muscle Strength; Quadriceps Muscle; Range of Motion, Articular; Thigh; Torque; Young Adult

The effects of two different 6-week lower body injury prevention programmes on knee muscle torque-angle relationship were examined in soccer players. Thirty-two men were randomly assigned to three groups: hamstring-eccentric (ECC) (n = 11), unstable-squatting (UNS) (n = 11), and control (n = 10). Intervention groups performed three training sessions per week using only three ECC or UNS exercises, respectively. Maximal peak knee flexion torque was measured at 35°, 45°, 60°, 80°, 90°, and 100°, pre- and post-intervention. Peak torque increased at 35° (P = 0.034, Cohen's d = 0.67) and 45° (P = 0.004, Cohen's d = 0.96) in the ECC group, and at 60° (P = 0.024, Cohen's d = 1.16), 80° (P = 0.018, Cohen's d = 1.21), and 90° (P = 0.001, Cohen's d = 1.38) in the UNS group. As these specific modifications might respectively and differentially protect athletes against hamstring and knee-joint injuries, the integration of both types of exercises should be considered when designing injury prevention programmes for soccer players.

Topics: Adult; Athletic Injuries; Humans; Knee Injuries; Lower Extremity; Male; Muscle Strength; Muscle, Skeletal; Resistance Training; Soccer; Thigh; Torque; Young Adult

The effects of a 4-week lower body injury prevention program on knee muscle torque-angle relationship were examined in soccer players. Twenty men were randomly allocated to either a control (n = 10) or training group (n = 10). The training group underwent three training sessions per week, comprising 3 sets of 8 repetitions of one open-chain exercise (Nordic curl) and two closed-chain exercises-forward lunges on a Bosu balance trainer and eccentric single leg dead lifts. Maximal peak knee flexion torque was measured at 35°, 45°, 60°, 80°, 90°, and 100° pre- and post-intervention. Significant improvements were observed only at 80° (p = .001; d = .94) along with a nonsignificant trend at 35° (p = .081; d = .43). As these modifications might protect athletes against muscle and joint injuries, the use of both stable-open and unstable-closed kinetic chain exercises emphasizing eccentric hamstring and knee stabilization actions should be integrated into injury prevention programs in team sports athletes.

Topics: Adult; Athletic Injuries; Humans; Knee Injuries; Knee Joint; Male; Muscle Contraction; Muscle, Skeletal; Program Evaluation; Resistance Training; Soccer; Torque; Young Adult

There is inconclusive evidence for the effectiveness of cryotherapy for the treatment of exercised-induced muscle damage (EIMD). Small sample sizes and treatment applications that did not correspond to evidence-based practice are limitations in previous studies that may have contributed to these equivocal findings. The purpose of this study was to examine the effectiveness of daily multiple applications of ice on EIMD throughout the 72-hour recovery period, an icing protocol that more closely resembles current clinical practice. Thirty-three subjects were assigned to either the cryotherapy group (n = 23) or control group (n = 10). The EIMD was induced through repeated isokinetic eccentric contractions of the right hamstring muscle group. The experimental group received ice immediately after induction of EIMD and continued to ice thrice a day for 20 minutes throughout the 72 hours; the control group received no intervention. Isometric torque, hamstring length, pain, and biochemical markers (creatine kinase [CK], alanine aminotransferase, and aspartate aminotransferase [AST]) were assessed at baseline, 24, 48, and 72 hours. Both groups demonstrated a significant change (p < 0.05) in all dependent variables compared with that at baseline, but there was no difference between groups except for pain. The cryotherapy group had significantly (p = 0.048) less pain (3.0 ± 2.1 cm) compared with the control (5.35 ± 2.5 cm) at 48 hours. Although not statistically significant, the cryotherapy group had a greater range of motion and lower CK and AST means at 72 hours compared with that of the control group. Repeated applications of ice can decrease the pain associated with EIMD significantly at 48 hours post EIMD. Although the results may not be unique, the methodology in this study was distinctive in that we used a larger sample size and an icing protocol similar to current recommended treatment practice.

Topics: Alanine Transaminase; Aspartate Aminotransferases; Athletic Injuries; Biomarkers; Case-Control Studies; Creatine Kinase; Cryotherapy; Female; Humans; Ice; Lower Extremity; Male; Muscle, Skeletal; Myalgia; Pain Measurement; Range of Motion, Articular; Torque; Young Adult

Controlled laboratory study.. To test for kinematic and kinetic differences between baseball pitching from a mound and long-toss on flat ground.. Long-toss throws from flat ground are commonly used by baseball pitchers for rehabilitation, conditioning, and training. However, there is controversy over the biomechanics and functionality of such throws.. Seventeen healthy, college baseball pitchers pitched fastballs 18.4 m from a mound to a strike zone, and threw 37 m, 55 m, and maximum distance from flat ground. For the 37-m and 55-m throws, participants were instructed to throw "hard, on a horizontal line." For the maximum-distance throw, no constraint on trajectory was given. Kinematics and kinetics were measured with a 3-dimensional, automated motion analysis system. Repeated-measures analyses of variance, with post hoc paired t tests, were used to compare the 4 throw types within pitchers.. At foot contact, the participant's shoulder line was nearly horizontal when pitching from a mound and became progressively more inclined as throwing distance increased. At arm cocking, the greatest amount of shoulder external rotation (mean ± SD, 180° ± 11°), elbow flexion (109° ± 10°), shoulder internal rotation torque (101 ± 17 Nm), and elbow varus torque (100 ± 18 Nm) were measured during the maximum-distance throws. Elbow extension velocity was also greatest for the maximum-distance throws (2573°/s ± 203°/s). Forward trunk tilt at the instant of ball release decreased as throwing distance increased.. Hard, horizontal, flat-ground throws have biomechanical patterns similar to those of pitching and are, therefore, reasonable exercises for pitchers. However, maximum-distance throws produce increased torques and changes in kinematics. Caution is, therefore, advised in the use of these throws for rehabilitation and training.

Topics: Athletic Injuries; Baseball; Elbow Injuries; Elbow Joint; Humans; Male; Motor Activity; Posture; Range of Motion, Articular; Rotation; Shoulder Injuries; Shoulder Joint; Torque; Weight-Bearing; Young Adult

The purpose of this study was to examine the effects of combined oral beta-hydroxy-beta-methylbutyrate (HMB) and alpha-ketoisocaproic acid (KIC) supplementation on indices of exercise-induced muscle damage (EIMD) after an acute bout of eccentric-biased exercise. Fourteen male subjects were allocated to 2 groups: a placebo group (3 g.d corn flour, N = 7) or an HMB + KIC group (3 g.d HMB and 0.3 g.d KIC, N = 7). Supplementation commenced 11 days before a 40-minute bout of downhill running and continued for 3 days post-exercise. Delayed-onset muscle soreness, mid-thigh girth, knee extensor range of motion, serum creatine kinase (CK) activity, and isometric and concentric torque were assessed pre-exercise and at 24, 48, and 72 hours post-exercise. Delayed-onset muscle soreness, CK activity, and isometric and concentric torque all changed over the 72-hour period (p < 0.05); however, HMB + KIC had no significant effect on any of the indices of muscle damage. Although 14 days HMB and KIC supplementation did not attenuate indices of EIMD after an acute bout of unaccustomed eccentric-biased exercise, there was a trend for a more rapid rate of recovery in isometric and isokinetic muscle function. beta-hydroxy-beta-methylbutyrate and KIC may therefore provide limited benefit in the recovery of muscle function after EIMD in untrained subjects or after unaccustomed exercise.

Topics: Analysis of Variance; Athletic Injuries; Creatine Kinase; Dietary Supplements; Humans; Keto Acids; Leg; Male; Muscle, Skeletal; Placebos; Range of Motion, Articular; Single-Blind Method; Torque; Valerates

Plyometric training is a widely used method to improve performance in healthy athletes. It is highly recommended in the late stage of rehabilitation of many lower limb injuries. However, its effects on muscle strength and function in management of lateral ankle sprain have not been reported. Therefore, the objective of the current study was to determine the effects of plyometric training versus resistive exercises on muscle strength and function following acute lateral ankle sprain.. Twenty-two athletes (aged from 20 to 35 years) of both sexes with grade I or II unilateral inversion ankle sprain participated in the study (at least 3 weeks after acute injury). They were randomly assigned to two groups. The first group received plyometric training, whereas the second one received resistive training for 6 weeks. Isokinetic peak torque/body weight for invertors and evertors at 30 degrees/s and 120 degrees/s and functional tests were assessed before and after training.. Both plyometric and resistive training improve isokinetic evertor and invertor peak torques and functional performance of athletes p < 0.05. There were no significant differences between groups concerning peak torque/body weight for invertors and evertors at both speeds measured p > 0.05. The functional test measures of the plyometric group were significantly higher than that of resistive group.. Plyometrics were more effective than resistive exercises in improving functional performance of athletes after lateral ankle sprain.

Topics: Adult; Ankle Injuries; Athletic Injuries; Female; Humans; Male; Muscle Contraction; Muscle Stretching Exercises; Prospective Studies; Resistance Training; Sprains and Strains; Torque

It is reported that thermotherapy decreases motoneuron-pool recruitment. Any decrease in recruitment might have a significant impact on an athlete's ability to return to competition.. To determine whether moist heat application influences involuntary motoneuron-pool recruitment or voluntary plantar-flexion peak torque of the soleus muscle immediately or 30 min after application.. A 3 x 3 crossover design.. Biomechanics laboratory.. Eighteen healthy subjects with no history of lower extremity surgery or injury 12 months before the study volunteered.. A series of short-duration, high-intensity stimuli was delivered to the tibial nerve to find the H(max) and M(max) measures. Immediately after the H(max) and M(max) measures, subjects were positioned on an isokinetic dynamometer where they performed 5 submaximal warm-up repetitions. Immediately after the warm-up, 5 maximum-intensity peak plantar-flexion torque repetitions were performed. After the dynamometer measures, subjects returned to the table, where a moist heat pack, no heat pack, or a dry nonheated heat pack was applied.. H(max), M(max), peak plantar-flexion torque, surface temperature (degrees C), and ambient temperature (degrees C).. Moist heat did not influence the H:M(max) ratio or peak plantar-flexion torque. Temperature increased with moist heat pack. Ambient temperature remained constant.. Moist heat did not influence involuntary motoneuron-pool recruitment or voluntary peak plantar-flexion torque of the soleus muscle immediately or 30 min after application.

Topics: Adult; Analysis of Variance; Athletic Injuries; Biomechanical Phenomena; Cross-Over Studies; Electromyography; Humans; Hyperthermia, Induced; Male; Motor Neurons; Muscle Contraction; Muscle Strength Dynamometer; Muscle, Skeletal; Torque

This study investigated whether 10 drop jumps (DJs) would confer protective effect against muscle damage and soreness in a subsequent bout of 50 DJs. Sixteen men were randomly placed into either a group performing 1 set of 10 DJs followed by 5 sets of 10 DJs (10-50, n = 8) or another group performing 2 bouts of 5 sets of 10 DJs (50-50, n = 8) separated by 2 weeks. The DJs were performed from a box height of 0.6 m, with a 10-second interval between jumps and a 1-minute rest between sets. Jump height, peak vertical ground reaction force, ground contact time, and heart rate during DJs were measured, and blood lactate concentration was assessed before and immediately after DJs. Changes in maximal isometric (ISO) and isokinetic concentric torque (CON), vertical jump, muscle soreness, and plasma creatine kinase activity before, immediately after, and at 1, 24, 48, and 72 hours following exercise were compared between groups for the first and second bouts and between the bouts by a 2-way repeated-measures analysis of variance. Changes in ISO, CON, vertical jump, and muscle soreness were significantly (p < 0.05) smaller for 10 DJs compared with 50 DJs; however, no significant differences in the measures between groups were evident following the second bout. The changes in the measures following 50 DJs in the 10-50 group were significantly (p < 0.05) smaller than those following the first bout of the 50-50 group. These results suggest that 10 DJs and 50 DJs conferred the same magnitude of protective effect against muscle damage by 50 DJs.

Topics: Athletic Injuries; Athletic Performance; Biomarkers; Creatine Kinase; Heart Rate; Humans; Knee; Lactic Acid; Male; Muscle, Skeletal; Pain; Physical Education and Training; Torque; Treatment Outcome

To study the effect of cycling or running retraining between 4 and 6 months after patients underwent anterior cruciate ligament reconstruction with hamstring grafting (Semitendinosus-Gracilis) compared with that in patients who had the same surgery but were untrained.. Patients who had undergone surgery for an anterior cruciate ligament reconstruction by the same surgeon who used hamstring grafting were included if they were free of knee pain 4 months after the surgery. After giving consent, patients were randomized to receive controlled retraining (cycling or running 3 times a week) or not. The effect of retraining was measured by the evolution of the knee isokinetic peak torque at 60 degrees/s and 180 degrees/s 6 months after surgery.. Fifteen patients were retrained with cycling (GI), 17 with running (GII) and 15 patients did not retrain (GIII). Before retraining, the 3 groups had the same peak torque deficit, measured at an angular speed of 60 degrees/s and 180 degrees/s, for knee extensors (GI: 33+/-11% and 27+/-8%; GII: 30+/-13% and 24+/-10%; GIII: 31+/-15% and 24+/-13%, respectively) and knee flexors (GI: 26+/-11% and 20+/-13%; GII: 20+/-14% and 17+/-13%; GIII: 19+/-15% and 14+/-15%, respectively). After retraining, progress measured at 60 degrees /s of knee extensors and flexors on the operated knees was 18+/-9% and 16+/-10% for GI, 16+/-9% and 11+/-11% for GII and 12+/-15% and 8+/-12 for GIII, respectively. Progress measured at 180 degrees /s followed the same evolution. After comparison of the 3 groups, any significant difference was put in relief according to the type of retraining.. Retraining after anterior cruciate ligament reconstruction is necessary for patients to practice their previous sport. In our study, aerobic cycling or running between 4 and 6 months after surgery did not improve peak torque in the operated knee extensors and flexors. However, these 2 types of retraining are well-tolerated.

Topics: Adult; Anterior Cruciate Ligament; Anterior Cruciate Ligament Injuries; Athletic Injuries; Bicycling; Female; Humans; Male; Physical Education and Training; Running; Tendons; Torque

Knee valgus load during sports movement is viewed as an important predictor of non-contact anterior cruciate ligament injury risk, particularly in females. Formulating movement strategies that can reduce valgus loading during these movements therefore appears pertinent to reducing anterior cruciate ligament injury rates. With this in mind, the current study examined the relationship between peak valgus moment and lower extremity postures at impact during a sidestep cutting task.. Ten male and ten female NCAA athletes had initial contact three-dimensional hip, knee and ankle angles and subsequent knee valgus moment quantified during the execution of (n=10 trials) sidesteps. Peak valgus data were normalized to mass and height and tested for the main effect of gender (ANOVA, P<0.05). Intra-subject correlations between the eight initial joint angles and the normalized valgus moment were then conducted across the ten sidestepping trials. The ensuing slopes of regression were submitted to a two-sample t-test to determine whether mean slope values were significantly different from zero and for the main effect of gender (P<0.05).. Females had significantly larger normalized knee valgus moments than males. A greater peak valgus moment was associated with larger initial hip flexion and internal rotation, and with larger initial knee valgus angle. Peak knee valgus moment was more sensitive to initial hip internal rotation and knee valgus position in females.. Training of neuromuscular control at the hip joint may reduce the likelihood of anterior cruciate ligament injury via a valgus loading mechanism during sidestepping, especially in females.

Topics: Adult; Anterior Cruciate Ligament; Anterior Cruciate Ligament Injuries; Athletic Injuries; Computer Simulation; Female; Humans; Knee Joint; Male; Models, Biological; Movement; Posture; Risk Assessment; Sports; Statistics as Topic; Stress, Mechanical; Torque; Weight-Bearing

The purpose of the study was to investigate landings in netball to ascertain whether or not an extra step on landing would significantly alter the forces on the body and to investigate the landings that were least stressful on the body. Eighteen State or Under 21 netball players participated as subjects. The subjects performed five different landing conditions at two pass heights. The five landing conditions were three legal landings consisting of a pivot, a run-on and a two foot landing. The other two landings used an extra step technique for the pivot and run-on landings. Data were collected using two force plates. The data were analysed using an ANCOVA, with approach speed as the covariate. The range of values for peak vertical ground reaction force were from 3.53 to 5.74 BW and for peak braking force the range was from 0.83 to 1.75 BW. No significant differences were found between each respective legal and extra step techniques. The run-on techniques exhibited lower peak forces, longer attenuation times and lower loading rates than the pivot or two foot landing conditions. The data clearly showed that there were no advantages to be gained from taking an extra step for either the pivot or run-on landing techniques. The run-on technique of landing appears to be most beneficial to reducing loads on the lower limb. A change to the footwork rules cannot be recommended based on the results of this study.

Topics: Adolescent; Adult; Ankle Joint; Athletic Injuries; Basketball; Deceleration; Female; Foot; Humans; Knee Injuries; Knee Joint; Physical Education and Training; Queensland; Running; Sports; Stress, Mechanical; Torque; Weight-Bearing

To assess quantitatively dynamics and extent of the increase in muscle strength during isokinetic rehabilitation.. daily measurements of muscle strength; detailed testing at the beginning and at the end of rehabilitation.. Cybex Rehabilitation Center, Zagreb.. 44 athletes (31 m, 13 F, age 16-35), 3 injury-defined groups: athletes with ACL rupture (non-reconstructed and reconstructed) and chondromalacia patellae.. all subjects underwent isokinetic rehabilitation on Cybex Orthotron KT2 device, using individually designed protocols (extension and flexion exercises, concentric muscle contractions, 15 treatments).. monitoring of daily progress on rehabilitation device and detailed testing on diagnostic device.. All patients showed considerable improvement. Muscle strength improved on average 141% (SD=110) in ACL-reconstructed group, 144% (SD=130) for chondromalacia patellae group and 150% (SD=74) for ACL-non-reconstructed group, comparing to initial strength. Dynamic status tested on Cybex Otrhotron diagnostic device prior and after rehabilitation strongly correlated with final progress monitored on the rehabilitation device.. Isokinetic rehabilitation is a quick and effective method in treating knee injuries in athletes. Both types of objective criteria have shown significant increase in muscle strength. The improvement of muscle strength was on the average 149% (SD=101), which is about 10% daily for 15 treatments. The greatest progress, 19% per day, occurred during first five days. The athletes were able to resume their sport activities as follows: patients from chondromalacia patellae group, and most of them from the non-reconstructed ACL group were back in competition within a month, while 75% from the ACL reconstructed group came back within 3 months, and the rest of them within 5 months.

Topics: Adolescent; Adult; Anterior Cruciate Ligament Injuries; Athletic Injuries; Cartilage, Articular; Female; Humans; Knee Injuries; Male; Muscle, Skeletal; Osteomalacia; Patella; Physical Therapy Modalities; Range of Motion, Articular; Recovery of Function; Rupture; Torque; Treatment Outcome

To examine the effect of six weeks of strength and proprioception training on eversion to inversion isokinetic strength ratios (E/I ratios) in subjects with unilateral functional ankle instability.. Thirty eight subjects were randomly assigned to one of four treatment groups: strength training (S); proprioception training (P); strength + proprioception training (B); control (C). Isokinetic strength was tested before and after training using a Kin Com 125 automatic positioning isokinetic dynamometer. Subtalar joint eversion and inversion motions were tested both concentrically and eccentrically through a range of motion involving 40 degrees. All peak torque and average torque values were normalised for body mass. E/I ratios were calculated from average torque and peak torque measures by taking the concentric eversion value and combining it with the eccentric inversion value. Data were analysed using a mixed model analysis of variance with repeated measures on the test factor. Average torque and peak torque E/I ratios at 30 and 120 degrees/s were analysed separately.. There were no significant differences in average torque and peak torque E/I ratios of the functionally unstable ankle for any of the groups after training compared with before.. Six weeks of strength and proprioception training (either alone or combined) had no effect on isokinetic measures of strength in subjects with self reported unilateral functional instability. Further studies examining this agonist (concentric) to antagonist (eccentric) muscle group strength ratio are needed.

Topics: Adult; Ankle Joint; Athletic Injuries; Exercise Therapy; Female; Humans; Joint Instability; Male; Muscle, Skeletal; Proprioception; Range of Motion, Articular; Torque

The purpose of this study was to compare changes in muscle damage indicators following 24 maximal eccentric actions of the elbow flexors (Max-ECC) between the arms that had been previously trained either eccentrically or concentrically for 8 wk.. Fifteen subjects performed three sets of 10 repetitions of eccentric training (ECC-T) with one arm and concentric training (CON-T) with the other arm once a week for 8 wk using a dumbbell representing 50% of maximal isometric force of the elbow flexors (MIF) determined at the elbow joint of 90 degrees (1.57 rad). The dumbbell was lowered from a flexed (50 degrees, 0.87 rad) to an extended elbow position (180 degrees, 3.14 rad) in 3 s for ECC-T, and lifted from the extended to the flexed position in 3 s for CON-T. Max-ECC was performed 4 wk after CON-T and 6 wk after ECC-T. Changes in MIF, range of motion (ROM), upper arm circumference (CIR), muscle soreness (SOR), and plasma creatine kinase (CK) activity were compared between the ECC-T and CON-T arms.. The first ECC-T session produced larger decreases in MIF and ROM, and larger increases in CIR and SOR compared with CON-T. CK increased significantly (P < 0.01) and peaked 4 d after the first training session, but did not increase in the following sessions. All measures changed significantly (P < 0.01) following Max-ECC; however, the changes were not significantly different between ECC-T and CON-T arms.. These results showed that ECC-T did not mitigate the magnitude of muscle damage more than CON-T, and CON-T did not exacerbate muscle damage.

Topics: Adaptation, Physiological; Adolescent; Adult; Anthropometry; Arm; Athletic Injuries; Creatine Kinase; Elbow; Exercise; Humans; Isometric Contraction; Male; Muscle, Skeletal; Pain; Physical Education and Training; Range of Motion, Articular; Torque; Weight Lifting

The goal of this prospective study was to determine the outcome-predictive role of various parameters in the nonoperative treatment of chronic anterior knee pain patients. Thirty patients followed a five-week treatment program, which consisted out of only closed kinetic chain exercises. Prior to this treatment all subjects were evaluated on muscular characteristics, subjective symptoms, weight, sex, duration of symptoms and functional performance. A multiple stepwise regression analysis revealed that the reflex response time of m. vastus medialis obliquus (VMO) (P=0.041; 0.026), and the duration of symptoms (P=0.019; 0.045) were the only two parameters which were significantly associated with the outcome (evaluated by the Kujala score) at five weeks, and at three months. The shorter the duration of symptoms, or the faster the reflex response time of VMO prior to the treatment, the better the outcome after a closed kinetic chain exercise program. The statistical significance of these parameters in this study may be seen as an indication of the importance of these variables as predictors of the outcome of a closed kinetic chain strengthening program. Using this information, it seems clinically important to begin the treatment program before the anterior knee pain becomes more chronic and treatment results become less good.

Topics: Adolescent; Adult; Arthralgia; Athletic Injuries; Exercise Therapy; Female; Humans; Knee Injuries; Male; Muscle Contraction; Muscle, Skeletal; Program Evaluation; Prospective Studies; Reflex, Stretch; Torque; Treatment Outcome

We have prospectively studied calf muscle strength (isokinetic concentric and eccentric muscle strength at 90 degrees/s and 225 degrees/s of angular velocity in 24 patients (17 males and 7 females, mean age 43.0 years) surgically treated for chronic Achilles tendinosis (at the 2-6 cm level in the tendon). The mean follow-up time was 5 years (range 31-82 months). Surgery was followed by immobilization in a weight-bearing below the knee plaster cast for 2-6 weeks, followed by a stepwise increasing strength training programme. Strength measurements (peak torque) were done preoperatively, and 1 and 5 (mean) years postoperatively. Preoperatively, concentric plantar flexion peak torque at 90 degrees/s and 225 degrees/s and eccentric plantar flexion torque at 90 degrees/s were significantly lower (12.3%, 19.7% and 8.5% respectively) on the injured side compared to the non-injured side. Postoperatively, at the 5-year follow-up, 22 out of 24 patients (92%) were satisfied with the operation and active at their desired level (running, tennis, badminton, walking). There was no significant increase in concentric and eccentric calf muscle strength postoperatively. Concentric plantar flexion peak torque at 90 degrees/s and 225 degrees/s and eccentric plantar flexion peak torque at 90 degrees/s were still significantly lower (7.2%, 8.6% and 8.8% respectively) on the injured side compared to the non-injured side. In conclusion it seems that the calf muscle strength deficit seen on the injured side preoperatively in this group of patients remains despite 92% of the patients being pain-free and active in sports or at recreational level after the operation. However, the percentage side-to-side difference is relatively low, and might not have any clinical relevance.

Topics: Achilles Tendon; Adult; Ankle; Athletic Injuries; Female; Follow-Up Studies; Humans; Isometric Contraction; Leg; Male; Middle Aged; Muscle Contraction; Muscle, Skeletal; Patient Satisfaction; Prospective Studies; Range of Motion, Articular; Recovery of Function; Tendinopathy; Torque; Treatment Outcome

With the gradual expansion of the development of sports, the level of sports has been rapidly improved. Athletes have to carry out high-intensity and systemic technical movements in training and competition. Some sports have the greatest burden on the shoulder joint. From the observation and investigation of the injured parts of athletes, it is found that the shoulder joint is the most common sports injury, which is the most typical sports injury. Based on the problem of insufficient strength and endurance reserve after rehabilitation of shoulder external rotator injury, it will cause muscle tension and poor extensibility. To prove the improvement effect of functional training and posture index calibration on the poor posture of the shoulder, considering the measurement of global passive torque, this paper uses a limited set of joint angles and corresponding passive torque data in the upper arm lifting trajectory to train the neural network and uses the trained network to predict the passive torque in other upper arm trajectories. The kinematics model of the shoulder joint is established, and the human-computer interaction experiment is designed on the platform of the gesture index manipulator. The passive and active torque components of the shoulder joint in the human-computer interaction process are calculated by measuring the man-machine interaction force of the subjects in the motion state, which is used as the basis for evaluating the active motion intention of the subjects. Surface electromyography (SEMG) was used to calibrate and verify the attitude index of shoulder active torque. The method proposed in this paper is helpful to achieve more efficient on-demand assisted rehabilitation training exercises, which is of great significance to improve the level of rehabilitation training.

Topics: Athletes; Athletic Injuries; Biomechanical Phenomena; Humans; Muscle, Skeletal; Posture; Shoulder Injuries; Shoulder Joint; Torque; Upper Extremity

Glenohumeral instability accounts for 23% of all shoulder injuries among collegiate athletes. The apprehension position-combined shoulder abduction and external rotation-commonly reproduces symptoms in athletes with instability. Rehabilitation aims to increase glenohumeral stability by strengthening functional positions. However, it is unclear how much glenohumeral stability increases with muscle contraction in the apprehension position. The purpose of this study was to determine whether the ability to increase translational glenohumeral stiffness, a quantitative measure of glenohumeral stability, with muscle contraction is reduced in the apprehension position.. Seventeen asymptomatic adults participated. A precision-instrumented robotic system applied pseudorandom, anterior-posterior displacements to translate the humeral head within the glenoid fossa and measured the resultant forces as participants produced isometric shoulder torques. Measurements were made in neutral abduction (90° abduction/0° external rotation) and apprehension (90° abduction/90° external rotation) positions. Glenohumeral stiffness was estimated from the relationship between applied displacements and resultant forces. The ability to increase glenohumeral stiffness with increasing torque magnitude was compared between positions.. On average, participants increased glenohumeral stiffness from passive levels by 91% in the neutral abduction position and only 64% in the apprehension position while producing 10% of maximum torque production. The biggest decrease in the ability to modulate glenohumeral stiffness in the apprehension position was observed for torques generated in abduction (49% lower, P < 0.001) and horizontal abduction (25% lower, P < 0.001).. Our results demonstrate that individuals are less able to increase glenohumeral stiffness with muscle contraction in the apprehension position compared with a neutral shoulder position. These results may help explain why individuals with shoulder instability more frequently experience symptoms in the apprehension position compared with neutral shoulder positions.

Topics: Adult; Athletic Injuries; Biomechanical Phenomena; Female; Humans; Joint Instability; Male; Muscle Contraction; Sex Characteristics; Shoulder Injuries; Shoulder Joint; Torque; Young Adult

Reduced sports function is often observed after hip arthroscopy for femoroacetabular impingement syndrome (FAIS). Impaired muscle strength could be reasons for this. We aimed to investigate hip muscle strength after hip arthroscopy for FAIS and its association with sports function and participation.. Cross-sectional study.. We included 45 patients (34 males; mean age: 30.6 ± 5.9 years) after unilateral hip arthroscopy for FAIS (mean follow-up [range]: 19.3 [9.8-28.4] months). Maximal isometric hip muscle strength (Nm/kg) including early- (0-100 ms) and late-phase (0-200 ms) rate of torque development (Nm∗kg. For maximal hip muscle strength, no between-hip differences were observed for adduction, abduction, flexion, and extension (p ≥ 0.102). For rate of torque development, significantly lower values were observed for the operated hip in flexion at both 0-100 ms (mean difference: 1.58 Nm∗kg. After hip arthroscopy for FAIS subjects show limited impairments in maximal and explosive hip muscle strength between operated and non-operated hip. Higher muscle strength was positively associated with higher sports function and ability to participate in sport.

Topics: Adult; Arthroscopy; Athletic Injuries; Cross-Sectional Studies; Female; Femoracetabular Impingement; Follow-Up Studies; Hip; Humans; Male; Muscle Strength; Patient Reported Outcome Measures; Return to Sport; Self Report; Torque; Weight-Bearing

Fatigue of the shoulder rotators may cause reduction of the subacromial space (SAS) and contribute to rotator cuff tendinopathy.. To compare the isokinetic peak torques and fatigue ratios of shoulder external rotators (ER) and internal rotators (IR) between elite softball athletes with and without rotator cuff tendinopathy and to investigate their associations with the SAS.. Cross-sectional study.. University laboratory.. Twenty-five elite softball players and 31 asymptomatic sedentary controls participated in this study.. Isokinetic concentric IR and ER peak torque and fatigue ratio were measured at 60°/s and at 180°/s, respectively; and ultrasound measurement of the SAS was measured during 0° and 60° of shoulder abduction.. Athletes with rotator cuff tendinopathy demonstrated lower peak torque in shoulder concentric ER when compared with their healthy counterparts (37.8 [5.8%] vs 43.6 [8.5%]). No significant difference was found in the fatigue ratios of ER, IR, and ER/IR when compared between elite softball athletes with and without rotator cuff tendinopathy (all P > .24). In asymptomatic athletes, greater IR peak torque (r = .583, P = .03), lower ER/IR strength ratio (r = -.605, P = .02), and greater ER/IR fatigue ratio (r = .575, P = .03) were moderately associated with more reduction of the SAS during 0° and 60° of shoulder abduction.. Decreased strength ratio and fatigue ratio of ER/IR were related to reduction of the SAS.

Topics: Adolescent; Adult; Athletic Injuries; Baseball; Female; Humans; Male; Muscle Fatigue; Rotation; Rotator Cuff Injuries; Shoulder Joint; Tendinopathy; Torque; Ultrasonography; Young Adult

Ultrasound imaging provides a cost-effective method of measuring quadriceps morphology, which may be related to self-reported function after anterior cruciate ligament reconstruction (ACLR).. To compare quadriceps morphology and strength between limbs in individuals with ACLR and matched control limbs and determine their associations with self-reported function.. Cross-sectional study.. Research laboratory.. Forty-two individuals with ACLR (females = 66%; age = 21.8 ± 2.6 years; time since ACLR = 50.5 ± 29.4 months) and 37 controls (females = 73%; age = 21.7 ± 1.2 years).. Quadriceps peak torque (PT) and rate of torque development were assessed bilaterally. Ultrasonography was used to measure the cross-sectional area (CSA) and echo intensity (EI) of the rectus femoris, vastus lateralis (VL), and vastus medialis. Self-reported function was assessed via the International Knee Documentation Committee (IKDC) score and Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales. Paired-samples. Isometric PT did not differ between limbs or groups. Involved limbs had a lower rate of torque development compared with the control (. Quadriceps morphology was associated with self-reported function in individuals with ACLR and may provide unique assessments of quadriceps function.

Topics: Anterior Cruciate Ligament Injuries; Anterior Cruciate Ligament Reconstruction; Athletic Injuries; Cross-Sectional Studies; Female; Humans; Knee; Knee Joint; Male; Muscle Strength; Muscle Weakness; Quadriceps Muscle; Quality of Life; Self Report; Torque; Ultrasonography; Young Adult

Persistent neuromuscular deficits in the surgical limb after anterior cruciate ligament reconstruction (ACLR) have been repeatedly described in the literature, yet little is known regarding their association with physical performance and patient-reported function.. To describe (1) interlimb differences in neuromuscular and functional outcomes and (2) the associations of neuromuscular outcomes with measures of physical and knee-related patient-reported function.. Cross-sectional study.. Laboratory.. Thirty individuals after primary, unilateral ACLR (19 males; age = 21.5 years [range, 14-41 years]; 8 months [range = 6-23 months] postsurgery).. Knee-extensor isometric and isokinetic peak torque was measured with an isokinetic dynamometer. Cross-sectional area (CSA) was measured bilaterally for each of the quadriceps muscles via magnetic resonance imaging. We measured quadriceps central activation bilaterally via the superimposed-burst technique. Physical performance (single-legged hop tests, step length via spatiotemporal gait analysis) and patient-reported outcomes (International Knee Documentation Committee questionnaire and Knee Injury and Osteoarthritis Outcome Score Sport and Recreation subscale) were also recorded. We conducted Wilcoxon signed rank tests to identify interlimb differences. Spearman ρ correlation analyses revealed associations between limb symmetry and neuromuscular and functional outcomes, as well as with patient-reported function.. Deficits in the surgical limb as compared with the nonsurgical limb were present for all outcomes (. Although deficits were observed in the surgical limb for all neuromuscular measures, greater symmetry in the size and strength of the quadriceps, rather than activation, was more strongly associated with physical performance after ACLR. Greater symmetry in strength was also more strongly associated with patient-reported function.

Topics: Adolescent; Adult; Anterior Cruciate Ligament Injuries; Anterior Cruciate Ligament Reconstruction; Athletic Injuries; Cross-Sectional Studies; Exercise Test; Female; Gait Analysis; Humans; Knee Injuries; Knee Joint; Male; Muscle Strength; Patient Reported Outcome Measures; Postoperative Complications; Quadriceps Muscle; Torque; Young Adult

There is a lack of definitive evidence supporting deficits in voluntary activation in participants with prior hamstring injury; moreover, it remains unknown if spinal mechanisms contribute to suspected deficits.. This study aimed to determine the effect of prior hamstring strain injury on knee flexor concentric and eccentric strength, voluntary activation, surface electromyographic (sEMG) activity, and stretch and tendon reflex amplitudes.. Twenty-five participants were recruited, 12 with a history of unilateral hamstring strain injury of at least moderate severity. Voluntary activation, strength, and sEMG activity were recorded during maximal eccentric and concentric knee flexor contractions at 60°·s. Stretch and tendon reflexes were also recorded at rest.. Previously injured limbs exhibited lower levels of voluntary activation (mean difference = -24.1%, 95% confidence interval [CI] = -34.1% to -14.0%, P < 0.001), strength (mean difference vs control group = -0.37 Nm·kg, 95% CI = -0.71% to -0.03 N·m·kg, P = 0.03), and normalized sEMG (mean difference = -17%, 95% CI = -32% to -2%, P = 0.02) during maximal eccentric knee flexor contractions compared with control group. No such differences were seen in concentric contractions. Stretch reflexes (mean difference = -3.8%, 95% CI = -6.8 to -0.8, P = 0.02) and tendon reflexes (mean difference = -13%, 95% CI = -26% to 0%, P = 0.04) were also lower in previously injured compared with control biceps femoris muscles.. Moderate to severe hamstring strain injury is associated with long-term deficits in voluntary activation during maximal eccentric contraction. Hamstring injury history is also associated with deficits in stretch reflex and tendon reflex amplitude.

Topics: Afferent Pathways; Athletic Injuries; Electromyography; Hamstring Muscles; Humans; Knee; Male; Muscle Contraction; Muscle Strength; Reflex, Stretch; Sprains and Strains; Tendons; Torque; Young Adult

Previous studies suggest that marathon running induces lower extremity muscle damage. This study aimed to examine inter- and intramuscular differences in hamstring muscle damage after a marathon using transverse relaxation time (T2)-weighted magnetic resonance images (MRI). 20 healthy collegiate marathon runners (15 males) were recruited for this study. T2-MRI was performed before (PRE) and at 1 (D1), 3 (D3), and 8 days (D8) after marathon, and the T2 values of each hamstring muscle at the distal, middle, and proximal sites were calculated. Results indicated that no significant intermuscular differences in T2 changes were observed and that, regardless of muscle, the T2 values of the distal and middle sites increased significantly at D1 and D3 and recovered at D8, although those values of the proximal site remained constant. T2 significantly increased at distal and middle sites of the biceps femoris long head on D1 (p = 0.030 and p = 0.004, respectively) and D3 (p = 0.007 and p = 0.041, respectively), distal biceps femoris short head on D1 (p = 0.036), distal semitendinosus on D1 (p = 0.047) and D3 (p = 0.010), middle semitendinosus on D1 (p = 0.005), and distal and middle sites of the semimembranosus on D1 (p = 0.008 and p = 0.040, respectively) and D3 (p = 0.002 and p = 0.018, respectively). These results suggest that the distal and middle sites of the hamstring muscles are more susceptible to damage induced by running a full marathon. Conditioning that focuses on the distal and middle sites of the hamstring muscles may be more useful in improving recovery strategies after prolonged running.

Topics: Athletic Injuries; Athletic Performance; Female; Hamstring Muscles; Humans; Isometric Contraction; Japan; Magnetic Resonance Imaging; Male; Running; Time Factors; Torque; Young Adult

Hamstring injuries remain the most common injury type across many professional sports. Despite a variety of intervention strategies, its incidence in soccer players playing in the UEFA Champions League has increased by 4% per year over the last decade. Test batteries trying to identify potential risk factors have produced inconclusive results. The purpose of the current study was to prospectively record hamstring injuries, to investigate the incidence and characteristics of the injuries, and to identify possible risk factors in elite male soccer players, playing in the Kosovo national premier league. A total of 143 soccer players from 11 teams in Kosovo were recruited. To identify possible prevalent musculoskeletal or medical conditions a widespread health and fitness assessment was performed including isokinetic strength testing, Nordic hamstring strength test, functional tests, and a comprehensive anamnesis surveying previous hamstring injuries. On average 27.9% of the players sustained at least one hamstring injury with three players suffering bilateral strains with the re-injury rate being 23%. Injured players were significantly older and heavier and had a higher body mass index compared to non-injured ones (p < 0.05). There was a lower passing rate in the Nordic hamstring strength test and a higher injury incidence among the previously injured players compared to non-injured ones (p < 0.05). Except for hamstring/quadriceps ratio and relative torque at 60°/sec (p < 0.05) for dominant and non-dominant leg, there were no other significant differences in isokinetic strength regardless of the angular velocity. No differences were observed for functional tests between cohorts. Regression analysis revealed that age, Nordic hamstring strength test, previous injury history, and isokinetic concentric torque at 240°/sec could determine hamstring injuries by 25.9%, with no other significant predicting risk factors. The battery of laboratory and field-based tests performed during preseason to determine performance related skills showed limited diagnostic conclusiveness, making it difficult to detect players at risk for future hamstring injuries.

Topics: Adult; Athletic Injuries; Body Mass Index; Exercise; Hamstring Muscles; Humans; Kosovo; Male; Muscle Strength; Muscular Diseases; Prognosis; Prospective Studies; Risk Factors; Soccer; Torque; Young Adult

Upper limb activities require a repetitive movement of the shoulder external rotator and abductor muscles. The malfunction of the proximal part of the upper limb kinetic chain tends to change the mechanics of the distal part and increase the risk of injuries.. To compare the normalized eccentric peak torque (NEPT) of the shoulder external rotator and abductor muscles among healthy athletes and those with tennis elbow and golfer's elbow.. An experimental cross-sectional study.. Isokinetic laboratory, Faculty of Physical Therapy, Cairo University.. A total of 30 male athletes participated voluntarily in this study.. Participants were distributed into 3 groups: healthy group, tennis elbow group, and golfer's elbow group.. NEPT of shoulder abductors and external rotators. The Biodex Isokinetic Dynamometer was used to measure the variables of interest.. There was a significant increase in the NEPT of shoulder abductors and external rotators in healthy control group compared with both tennis elbow and golfer's elbow groups at an angular velocity of 60°/s (P < .05). Moreover, there was a significant increase in the NEPT of shoulder external rotators and abductors at an angular velocity of 120°/s in healthy control group compared with tennis elbow group and in golfer's elbow group compared with tennis elbow group (P < .05).. Tennis elbow and golfer's elbow are associated with decreased NEPT of shoulder external rotators and abductors compared with those of healthy athletes. This tends to decrease the external stability of the shoulder joint and put high stress on the distal joints of the upper kinetic chain.

Topics: Adult; Athletic Injuries; Case-Control Studies; Disability Evaluation; Elbow Tendinopathy; Golf; Humans; Male; Muscle Strength; Muscle, Skeletal; Pain Measurement; Shoulder Joint; Tennis; Torque; Young Adult

Waiter's serve (WS) is a specific tennis serve posture frequently observed in young players, and commonly considered as a technical error by tennis coaches. However, biomechanical impact of WS is unknown. The aims of this study were to identify the potential consequences of WS in young elite players relating to performance and injury risk, and to explain the kinematic causes of WS. Serve of 18 male junior elite players (Top 10 national French ranking, aged 12-15 years) was captured with a 20 camera, 200 Hz VICON MX motion analysis system. Depending on their serve technique, the players were divided into two groups (WS versus Normal Serve [NS]) by experienced coaches. Injury data were collected for each player during a 12-month-period following the motion capture. Normalized peak kinetic values of the dominant arm were calculated using inverse dynamics. In order to explain WS posture, upper limb kinematics were calculated during the cocking and the acceleration phases of the serve. Shoulder internal rotation torque, wrist proximal and anterior forces (

Topics: Adolescent; Arm; Athletic Injuries; Biomechanical Phenomena; Child; Cumulative Trauma Disorders; Elbow; Humans; Male; Posture; Shoulder; Tennis; Torque; Upper Extremity; Wrist

Throwing athletes with ulnar collateral ligament (UCL) injury and symptomatic valgus instability can expect to return to the same or higher level of play. Reconstruction with tendon graft is the dominant method of surgical treatment. Recent evidence suggests that spanning the joint with a suture anchored on both sides is biomechanically equivalent to reconstruction, with faster time to return to play. The authors developed a hybrid UCL reconstruction technique augmented with a suture brace to improve joint stability.. The purpose of this study was to biomechanically evaluate a hybrid reconstruction technique and compare its performance to reconstruction without augmentation. The authors hypothesized that (1) both groups would lose stability after the simulated tear and regain stability with treatment, (2) the suture augmentation would improve stability, and (3) the addition of the suture anchors near the bone tunnels would not decrease the strength of the hybrid reconstruction.. Controlled laboratory study.. Ten matched pairs of cadaveric arms were dissected to expose the UCL. Each elbow was mounted on a test frame at 90° of flexion. A cyclic valgus rotational torque was applied to the humerus with the UCL in its intact state and repeated in its surgically torn state. Finally, each specimen received either a hybrid reconstruction with suture brace or a reconstruction and was again put through the cyclic protocol, followed by a valgus rotation load-to-fail protocol.. Gap formation in the torn state for the reconstruction and hybrid reconstruction groups (0.9 ± 0.1 mm and 0.8 ± 0.1 mm, respectively) was significantly higher ( P = .009 and P = .0002) than in the intact state (0.6 ± 0.2 mm and 0.6 ± 0.3 mm, respectively). After the procedures, the hybrid group showed greater resistance to gapping ( P = .017) as compared with the reconstruction group (0.4 ± 0.2 mm and 0.6 ± 0.1 mm). During load to failure, no hybrid reconstructions failed from bone fracture or screw pullout. No statistical differences were found for failure torque ( P = .058) and stiffness ( P = .101). Gap at 10 N·m was significantly lower ( P = .014) for the hybrid reconstruction group than for the reconstruction group.. The current study showed that hybrid reconstruction with suture bracing replicated the time-zero strength of traditional UCL reconstruction and may be more resistant to joint gapping during low cyclic load and load to failure. The combination of the bone tunnels and fixation screw holes did not appear to weaken the construct.. This study demonstrated that reconstruction with suture bracing has important time-zero stability and strength as compared with the gold standard of UCL reconstruction. This technique may be useful for throwing athletes who need UCL reconstruction.

Topics: Adult; Athletic Injuries; Biomechanical Phenomena; Bone Screws; Cadaver; Collateral Ligament, Ulnar; Humans; Humerus; Male; Middle Aged; Range of Motion, Articular; Rotation; Suture Anchors; Suture Techniques; Torque; Ulnar Collateral Ligament Reconstruction; Young Adult

High loads in the elbow during baseball pitching can lead to serious injuries, including injuries to the ulnar collateral ligament. These injuries have substantial implications for individual pitchers and their teams, especially at the professional level of competition. With a trend toward increased ball velocity in professional baseball, controversy still exists regarding the strength of the relationship between ball velocity and elbow-varus torque.. To examine the relationship between fastball velocity and elbow-varus torque in professional pitchers using between- and within-subjects statistical analyses.. Cross-sectional study.. Motion-analysis laboratory.. Using the previously collected biomechanical data of 452 professional baseball pitchers, we performed a retrospective analysis of the 64 pitchers (52 right-hand dominant, 12 left-hand dominant; age = 21.8 ± 2.0 years, height = 1.90 ± 0.05 m, mass = 94.6 ± 7.8 kg) with fastball velocity distributions that enabled between- and within-subjects statistical analyses.. We measured ball velocity using a radar gun and 3-dimensional motion data using a 12-camera automated motion-capture system sampling at 240 Hz. We calculated elbow-varus torque using inverse-dynamics techniques and then analyzed the relationship between ball velocity and elbow torque using both a simple linear regression model and a mixed linear model with random intercepts.. The between-subjects analyses displayed a weak positive association between ball velocity and elbow-varus torque (. When comparing 2 professional baseball pitchers, higher velocity may not necessarily indicate higher elbow-varus torque due to the confounding effects of pitcher-specific differences (eg, detailed anthropometrics and pitching mechanics). However, within an individual pitcher, higher ball velocity was strongly associated with higher elbow-varus torque.

Topics: Anthropometry; Athletic Injuries; Baseball; Biomechanical Phenomena; Collateral Ligament, Ulnar; Cross-Sectional Studies; Elbow Injuries; Elbow Joint; Humans; Male; Retrospective Studies; Rotation; Torque; Young Adult

We recently reported that wearing unstable rocker shoes (Masai Barefoot Technology: MBT) may enhance recovery from marathon race-induced fatigue. However, this earlier study only utilized a questionnaire. In this study, we evaluated MBT utilizing objective physiological measures of recovery from marathon-induced muscle damages. Twenty-five university student novice runners were divided into two groups. After running a full marathon, one group wore MBT shoes (MBT group), and the control group (CON) wore ordinary shoes daily for 1 week following the race. We measured maximal isometric joint torque, muscle hardness (real time tissue elastography of the strain ratio) in the lower limb muscles before, immediately after, and 1, 3, and 8 days following the marathon. We calculated the magnitude of recovery by observing the difference in each value between the first measurement and the latter measurements. Results showed that isometric torques in knee flexion recovered at the first day after the race in the MBT group while it did not recover even at the eighth day in the CON group. Muscle hardness in the gastrocnemius and vastus lateralis showed enhanced recovery in the MBT group in comparison with the CON group. Also for muscle hardness in the tibialis anterior and biceps femoris, the timing of recovery was delayed in the CON group. In conclusion, wearing MBT shoes enhanced recovery in lower leg and thigh muscles from muscle damage induced by marathon running.

Topics: Athletic Injuries; Female; Humans; Lower Extremity; Male; Muscle Fatigue; Muscle Tonus; Muscle, Skeletal; Running; Shoes; Torque; Young Adult

Muscular fatigue and interlimb strength asymmetry are factors known to influence hamstring injury risk; however, limb-specific exacerbation of knee flexor (hamstrings) torque production after fatiguing exercise has previously been ignored. To investigate changes in muscular force production before and after sport-specific (repeated-sprint) and non-specific (knee extension-flexion) fatiguing exercise, and explore the sensitivity and specificity of isokinetic endurance (ie, muscle-specific) and single-leg vertical jump (ie, whole limb) tests to identify previous hamstring injury. Twenty Western Australia State League footballers with previous unilateral hamstring injury and 20 players without participated. Peak concentric knee extensor and flexor (180°∙s

Topics: Athletes; Athletic Injuries; Australia; Fatigue; Humans; Knee; Quadriceps Muscle; Range of Motion, Articular; Running; Soccer; Torque

Topics: Athletes; Athletic Injuries; Basketball; Female; Gymnastics; Hamstring Muscles; Humans; Knee Injuries; Knee Joint; Muscle Strength; Quadriceps Muscle; Torque; Young Adult

Determine whether clinically feasible tests of isometric lower limb strength and range of motion (ROM) in Australian Football (AF) athletes are useful in Periodic Health Examinations to identify persistent deficits following hamstring strain injury (HSI).. Case-control.. Thirty-seven male, semi-professional AF athletes (mean±SD; age, 20.2±2.9years; height, 1.7±0.5m; mass, 81±9.2kg) participated, ten athletes (37%) reported HSI within the previous three seasons of competition. Comparisons of pre-season isometric knee flexion and hip extension strength variables (peak force, torque and torque normalised to body mass) and hip, knee and ankle ROM measures were made between athletes with and without past-history of HSI using linear mixed-effect models. A logistic regression evaluated whether any of the outcome measures could differentiate athletes with a past-history of HSI.. Knee flexion peak force, torque and torque normalised to body mass were significantly reduced in athletes with a past-history of HSI (coefficient, 95% CI) (-44.8N, -86.3 to -3.3), (-22.2Nm, -40.5 to -3.7) and (-0.2Nmkg. Deficits in isometric peak knee flexion strength persist for up to three seasons following HSI in AF athletes. Isometric knee flexion strength testing may be a clinically feasible option for Periodic Health Examinations and inform tertiary injury prevention strategies.

Topics: Adolescent; Athletes; Athletic Injuries; Australia; Case-Control Studies; Football; Hamstring Muscles; Hip; Humans; Knee Joint; Leg Injuries; Male; Muscle Strength; Range of Motion, Articular; Sprains and Strains; Torque; Young Adult

In elite sport, the use of strength testing to establish muscle function and performance is common. Traditionally, isokinetic strength tests have been used, measuring torque during concentric and eccentric muscle action. A device that measures eccentric hamstring muscle strength while performing the Nordic hamstring exercise is now also frequently used. The study aimed to investigate the variability of isokinetic muscle strength over time, for example, between seasons, and the relationship between isokinetic testing and the new Nordic hamstring exercise device. All teams (n = 18) eligible to compete in the premier football league in Qatar underwent a comprehensive strength assessment during their periodic health evaluation at Aspetar Orthopaedic and Sports Medicine Hospital in Qatar. Isokinetic strength was investigated for measurement error, and correlated to Nordic hamstring exercise strength. Of the 529 players included, 288 players had repeated tests with 1/2 seasons between test occasions. Variability (measurement error) between test occasions was substantial, as demonstrated by the measurement error (approximately 25 Nm, 15%), whether separated by 1 or 2 seasons. Considering hamstring injuries, the same pattern was observed among injured (n = 60) and uninjured (n = 228) players. A poor correlation (r = .35) was observed between peak isokinetic hamstring eccentric torque and Nordic hamstring exercise peak force. The strength imbalance between limbs calculated for both test modes was not correlated (r = .037). There is substantial intraindividual variability in all isokinetic test measures, whether separated by 1 or 2 seasons, irrespective of injury. Also, eccentric hamstring strength and limb-to-limb imbalance were poorly correlated between the isokinetic and Nordic hamstring exercise tests.

Topics: Adult; Athletes; Athletic Injuries; Exercise Test; Hamstring Muscles; Humans; Male; Muscle Strength; Muscle Strength Dynamometer; Prospective Studies; Qatar; Quadriceps Muscle; Reproducibility of Results; Soccer; Torque; Young Adult

There has been an increasing incidence of overuse elbow injuries among youth and adolescent pitchers. Pitch type has been implicated as a risk factor for excess torque at the medial elbow; however, this has not been definitively demonstrated.. To assess predictors of torque across the medial elbow in youth and adolescent pitchers with a mobile sensor. In addition, the authors aimed to determine the differences in elbow torque produced according to pitch type (fastball, curveball, changeup) and pitcher demographics.. Descriptive laboratory study.. Twenty youth and adolescent pitchers were instructed to throw 8 fastballs, 8 curveballs, and 8 changeups in a standardized but randomized sequence over a 25-minute period. Five pitchers were evaluated each day. A sensor placed at the medial elbow reported elbow torque, arm speed, arm slot, and shoulder rotation for each pitch, while a radar gun measured peak ball velocity. The primary outcome was a determination of thrower and pitch characteristics associated with elevated torque across the medial elbow. Secondary outcomes included the evaluation of differences in throwing biomechanics among different pitch types. Outcomes were assessed via a multivariable model, which controlled for possible covariates.. In total, 20 youth baseball pitchers with a mean age of 14.1 years (range, 12-17 years) were included in the study. On average, fastballs caused the greatest torque across the medial elbow (least squares mean ± SE, 47.3 ± 0.5 N·m) as compared with changeups (44.2 ± 0.5 N·m; P < .001) and curveballs (45.0 ± 0.5 N·m; P = .002). However, curveballs produced the greatest arm speed (917.8 rpm). Pitchers who started throwing curveballs at an older age experienced less elbow torque ( P < .001). A multivariable model demonstrated that increased ball velocity and body mass index and decreased arm slot were independent predictors of increased elbow torque. Conversely, increasing age, longer arm length, and greater elbow circumference were independent protectors against elbow torque.. This study found that among youth and adolescent pitchers, fastballs generate the highest elbow torque while curveballs generated the greatest arm speed. Increased ball velocity and body mass index and decreased arm slot were predictors of elbow torque; however, increasing age and size of a pitcher's arm were protectors against elbow torque. These findings are important to better understand risk factors for overuse injury in this at-risk athletic population.. These findings may inform future pitching recommendations with intentions of curtailing medial elbow injuries experienced by young pitchers, such as ulnar collateral ligament injuries.

Topics: Adolescent; Athletic Injuries; Baseball; Biomechanical Phenomena; Elbow Injuries; Humans; Male; Torque; United States

Hamstring injuries remain a significant burden in sports that involve high-speed running. In elite male football, hamstring injury has repeatedly been identified as the most common non-contact injury, representing 12% of all injuries. As the incidence remains high, investigations are aimed at better understanding how to improve prevention efforts. Intrinsic risk factors such as strength have been investigated extensively in a cohort of professional football players; however, other intrinsic measures of neuromuscular function have not been studied in this cohort. This study aims to investigate the association between timing of hamstring muscle activity onset and the rate of torque development during the early phase of isokinetic strength testing with risk of hamstring injury in professional football players in a prospective cohort study. All teams (n = 18) eligible to compete in the premier football league in Qatar underwent a comprehensive strength assessment during their annual periodic health evaluation at Aspetar Orthopaedic and Sports Medicine Hospital in Doha, Qatar. Variables included rate of torque development and timing of muscle activity onset. A total of 367 unique players (60.6% of all QSL players) competed for 514 player seasons (103 players competed both seasons) and sustained 65 hamstring injuries. There was no difference in the onset of muscle activity between the biceps femoris and medial hamstrings comparing the injured to uninjured players. For both onset of muscle activity and rate of torque development, there were no significant differences between any of the variables (P > .05), with small effect sizes detected across all the different variables (d < 0.3). Rate of torque development and onset of muscle activity were not associated with a risk of future hamstring injury. The use of these measures as part of a periodic health evaluation to identify risk of hamstring injury is unsupported.

Topics: Adult; Athletes; Athletic Injuries; Electromyography; Hamstring Muscles; Humans; Leg Injuries; Male; Muscle Contraction; Prospective Studies; Qatar; Risk Factors; Soccer; Torque; Young Adult

  Despite an increase in the literature, few definitive guidelines are available to determine when an athlete has been fully rehabilitated after anterior cruciate ligament reconstruction (ACLR)..   To examine countermovement jump and isokinetic dynamometry measures to (1) identify which measures can best distinguish between ACLR and control participants and (2) provide normative values for identified measures in young adult male multidirectional field-sport athletes..   Cross-sectional study..   Orthopaedic hospital..   Young adult male multidirectional field-sport athletes (n = 118) who had undergone unilateral patellar-tendon graft ACLR at least 6 months earlier and healthy male participants (n = 44) with no previous knee injury..   Single-legged countermovement jump (SL CMJ)..   Three-dimensional biomechanical analysis of the SL CMJ and mean peak concentric knee-extension and -flexion torque using isokinetic dynamometry (ISO) were compared in the 2 groups. A stepwise logistic regression was carried out to identify the best predictors of ACLR- or control-group membership (SL CMJ height, limb symmetry index, peak power, joint power contribution, ISO peak torque, limb symmetry index variables)..   The control group differed strongly from the ACLR group in isokinetic knee-extension peak torque (d = -1.33), SL CMJ performance (d > 0.4), and limb symmetry measures in both ISO and jump outcomes (d > 1.1). The combination of measures from both ISO and SL CMJ identified group membership with an accuracy of 89%..   Rehabilitation of ACLR patients may be complete when they achieve isokinetic knee-extension peak torque of 260% (±40%) body mass, SL CMJ performance of >17 cm (±4 cm), and reach-limb symmetry measures of >90% in both strength and jump outcomes. The outcomes in the control group can inform return-to-play criteria for young adult male multidirectional field-sport athletes after ACLR.

Topics: Adult; Anterior Cruciate Ligament Injuries; Anterior Cruciate Ligament Reconstruction; Athletes; Athletic Injuries; Cross-Sectional Studies; Exercise Test; Female; Humans; Male; Muscle Strength; Muscle Strength Dynamometer; Quadriceps Muscle; Range of Motion, Articular; Torque; Young Adult

To present the case of a 15 year-old baseball player with Little League Shoulder (LLS) and describe how developmental changes in the angle of humeral retrotorsion (HRT) may contribute to the underlying pathology of this condition.. Case report.. Two years earlier, the patient had participated in a healthy player screening program at which time measurements of height, weight, shoulder motion, and HRT were obtained. These same measures were obtained during the initial evaluation after injury. Between measurements, the patient grew more than 12 cm in height and demonstrated a large shift in proximal humeral torsional alignment with a change of 13° and 19° of HRT in the dominant and non-dominant sides respectively.. 15 year-old male (1.88 m, 79.8 kg), right hand dominant baseball pitcher and 3rd baseman diagnosed with right LLS.. The pathoanatomical factors contributing to LLS are not well understood. The degree of HRT is a developmental characteristic that changes over the course of physiological maturation. The large changes in HRT seen in this case, may implicate rapid changes in HRT angle create a window of increased susceptibility to physeal damage, and contribute to the development of LLS.

Topics: Adolescent; Athletic Injuries; Baseball; Humans; Humerus; Male; Range of Motion, Articular; Rotation; Shoulder Injuries; Torque

Although cold application (ie, cryotherapy) may be useful to treat sports injuries and to prevent muscle damage, it is unclear whether it has adverse effects on muscle mechanical properties. This study aimed to determine the effect of air-pulsed cryotherapy on muscle stiffness estimated using ultrasound shear wave elastography. Myoelectrical activity, ankle passive torque, shear modulus (an index of stiffness), and muscle temperature of the gastrocnemius medialis were measured before, during an air-pulsed cryotherapy (-30°C) treatment of four sets of 4 minutes with 1-minute recovery in between and during a 40 minutes postcryotherapy period. Muscle temperature significantly decreased after the second set of treatment (10 minutes: 32.3±2.5°C; P<.001), peaked at 29 minutes (27.9±2.2°C; P<.001) and remained below baseline values at 60 minutes (29.5±2.0°C; P<.001). Shear modulus increased by +11.5±11.8% after the second set (10 minutes; P=.011), peaked at 30 minutes (+34.7±42.6%; P<.001), and remained elevated until the end of the post-treatment period (+25.4±17.1%; P<.001). These findings provide evidence that cryotherapy induces an increase in muscle stiffness. This acute change in muscle mechanical properties may lower the amount of stretch that the muscle tissue is able to sustain without subsequent injury. This should be considered when using cryotherapy in athletic practice.

Topics: Adult; Ankle; Athletic Injuries; Cryotherapy; Elastic Modulus; Elasticity Imaging Techniques; Female; Humans; Male; Muscle Strength Dynamometer; Muscle, Skeletal; Torque

Alpine touring (AT) equipment is designed for ascending mountains and snow skiing down backcountry terrain. Skiers have been observed using AT boots in alpine (not made for Alpine Touring) ski bindings. We tested the effect on the retention-release characteristics of AT boots used in alpine bindings. Ten AT ski boots and 5 alpine ski boots were tested in 8 models of alpine ski bindings using an ASTM F504-05 (2012) apparatus. Thirty-one percent of the AT boots released appropriately when used in alpine ski bindings. One alpine binding released appropriately for all alpine and AT boots tested; 2 alpine ski bindings did not release appropriately for any AT boots. Altering the visual indicator settings on the bindings (that control the release torque of an alpine system) had little or no effect on the release torque when using AT boots in alpine ski bindings. Many combinations released appropriately in ski shop tests, but did not release appropriately in the more complex loading cases that simulated forward and backward falls; the simple tests performed by ski shops could produce a "false-negative" test result. These results indicate that using AT boots with alpine ski bindings could increase the likelihood of lower leg injuries.

Topics: Athletic Injuries; Equipment Failure Analysis; Humans; Shoes; Skiing; Sports Equipment; Torque

The purpose of the present study was to examine knee extensor and flexor muscle strength ratios of an elite group of diving athletes.. Elite diving athletes demonstrated high knee extensor and low knee flexor strength. This partially explains their low F/E ratio, which might increase risk of knee injuries. Strength and conditioning programs should strive to correct knee strength imbalances in diving athletes where necessary.

Topics: Adolescent; Adult; Athletes; Athletic Injuries; Brazil; Diving; Female; Humans; Knee; Knee Injuries; Knee Joint; Lower Extremity; Male; Muscle Strength; Muscle, Skeletal; Torque; Young Adult

Hamstrings grafts are commonly used in ACL reconstruction, however, the effect of graft harvesting on knee flexion strength has not been longitudinally evaluated in functional positions. We hypothesized that greater deficits in knee flexion strength exist in the prone compared to the seated position and these deficits remain as rehabilitation progresses.. Case series.. Forty-two consecutive patients who underwent ACL reconstruction with a hamstrings graft were followed prospectively for 9 months. Isokinetic knee flexion strength at a slow and a fast speed were collected at 3, 4, 6, and 9 months in two different positions: conventional (seated) and functional (0° of hip flexion).. Peak torque knee flexion deficits were higher in the prone position compared to the seated position by an average of 6.5% at 60°/s and 9.1% at 180°/s (p<0.001).. Measuring knee flexion strength in prone demonstrates higher deficits than in the conventional seated position. Most athletes would not be cleared to return to sports even at 9 months after surgery with this method.

Topics: Adult; Analysis of Variance; Anterior Cruciate Ligament Reconstruction; Athletic Injuries; Female; Hamstring Tendons; Humans; Knee Joint; Male; Muscle, Skeletal; Posture; Prone Position; Prospective Studies; Range of Motion, Articular; Return to Sport; Torque; Young Adult

The number of throwing athletes with ulnar collateral ligament (UCL) injuries has increased recently, with a seemingly exponential increase of such injuries in adolescents. In cases of acute proximal or distal UCL insertion injuries or in partial-thickness injuries that do not respond to nonoperative management, UCL repair and augmentation rather than reconstruction may be a viable option.. The purpose of this study was to biomechanically compare a new technique of augmented UCL repair versus a typical modified Jobe UCL reconstruction technique. The hypotheses were that (1) the repaired specimens would have less gap formation and a higher maximal torque to failure compared with the reconstruction group, and (2) while both groups would show an increase in gap formation after the simulated tear, the repair group would return closer to the native values compared with the reconstruction group.. Controlled laboratory study.. Nine matched pairs of cadaveric arms were dissected to expose the UCL. Each elbow was mounted on a test frame at 90° of flexion. A cyclic valgus rotational torque was applied to the humerus with the UCL in its intact state and repeated in its surgically torn state. Finally, each specimen received either an augmented repair or reconstruction and was again put through the cyclic protocol, followed by a torque to failure.. Gap formation (0.51 ± 0.22 mm) in the torn state for the repair group was significantly higher (P = .04) than in the intact state (0.33 ± 0.12 mm). After the procedures, the repair group (0.35 ± 0.16 mm) showed greater resistance to gapping (P = .03) compared with the reconstruction group (0.53 ± 0.23 mm). No statistical differences were found for the maximum torque at failure, torsional stiffness, or gap formation during the failure test.. The current study shows that this novel technique of augmented UCL repair replicates the time-zero failure strength of traditional graft reconstruction and appears to be more resistant to gapping at low cyclic loads.. This study demonstrates that this novel technique has important biomechanical properties, including time-zero strength and ultimate failure load, compared with the gold standard of UCL reconstruction. In some throwing athletes, this technique may supplant standard UCL reconstruction as the procedure of choice.

Topics: Adolescent; Athletic Injuries; Biomechanical Phenomena; Braces; Cadaver; Collateral Ligaments; Elbow Injuries; Humans; Humerus; Male; Orthopedic Procedures; Range of Motion, Articular; Rupture; Torque; Ulna

When returning to physical activity, patients with a history of anterior cruciate ligament reconstruction (ACL-R) often experience limitations in knee-joint function that may be due to chronic impairments in quadriceps motor control. Assessment of knee-extension torque variability may demonstrate underlying impairments in quadriceps motor control in patients with a history of ACL-R.. To identify differences in maximal isometric knee-extension torque variability between knees that have undergone ACL-R and healthy knees and to determine the relationship between knee-extension torque variability and self-reported knee function in patients with a history of ACL-R.. Descriptive laboratory study.. Laboratory.. A total of 53 individuals with primary, unilateral ACL-R (age = 23.4 ± 4.9 years, height = 1.7 ± 0.1 m, mass = 74.6 ± 14.8 kg) and 50 individuals with no history of substantial lower extremity injury or surgery who served as controls (age = 23.3 ± 4.4 years, height = 1.7 ± 0.1 m, mass = 67.4 ± 13.2 kg).. Torque variability, strength, and central activation ratio (CAR) were calculated from 3-second maximal knee-extension contraction trials (90° of flexion) with a superimposed electrical stimulus. All participants completed the International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form, and we determined the number of months after surgery. Group differences were assessed using independent-samples t tests. Correlation coefficients were calculated among torque variability, strength, CAR, months after surgery, and IKDC scores. Torque variability, strength, CAR, and months after surgery were regressed on IKDC scores using stepwise, multiple linear regression.. Torque variability was greater and strength, CAR, and IKDC scores were lower in the ACL-R group than in the control group (P < .05). Torque variability and strength were correlated with IKDC scores (P < .05). Torque variability, strength, and CAR were correlated with each other (P < .05). Torque variability alone accounted for 14.3% of the variance in IKDC scores. The combination of torque variability and number of months after surgery accounted for 21% of the variance in IKDC scores. Strength and CAR were excluded from the regression model.. Knee-extension torque variability was moderately associated with IKDC scores in patients with a history of ACL-R. Torque variability combined with months after surgery predicted 21% of the variance in IKDC scores in these patients.

Topics: Adult; Anterior Cruciate Ligament; Anterior Cruciate Ligament Injuries; Anterior Cruciate Ligament Reconstruction; Athletic Injuries; Exercise; Female; Humans; Knee Injuries; Knee Joint; Male; Muscle Strength; Quadriceps Muscle; Range of Motion, Articular; Recreation; Return to Sport; Self Report; Torque; Young Adult

In this study we aimed to quantify the effect of exercise-induced muscle damage on both the electrochemical and mechanical components of electromechanical delay using very-high-frame-rate ultrasound.. Fifteen participants underwent electrically evoked contractions of the medial gastrocnemius muscle with an ultrasound transducer on the muscle belly and on the myotendinous junction, before, 1 hour, and 48 hours after eccentric exercise of the plantar flexor muscles.. Maximal isometric plantar flexor torque was significantly lower at 1 hour (-41.1 ± 14.9%; P = 0.0001) and 48 hours (-11.9 ± 14.9%; P = 0.038) post-exercise compared with pre-exercise. However, the delay between electrical stimulation and the onset of muscle activation, the delay between electrical stimulation and myotendinous junction motion, and the electromechanical delay were not altered significantly by eccentric exercise (P = 0.063).. These findings suggest that moderate muscle damage does not affect the time for the electrochemical or mechanical components of electromechanical delay. Muscle Nerve 54: 136-141, 2016.

Topics: Adult; Analysis of Variance; Athletic Injuries; Biomechanical Phenomena; Electric Stimulation; Electromyography; Ergometry; Female; Humans; Isometric Contraction; Male; Muscle Strength; Muscle, Skeletal; Myalgia; Reaction Time; Torque; Ultrasonography; Young Adult

Tibial slope angle is a nonmodifiable risk factor for anterior cruciate ligament (ACL) injury. However, the mechanical role of varying tibial slopes during athletic tasks has yet to be clinically quantified.. To examine the influence of posterior tibial slope on knee joint loading during controlled, in vitro simulation of the knee joint articulations during athletic tasks.. Descriptive laboratory study.. A 6 degree of freedom robotic manipulator positionally maneuvered cadaveric knee joints from 12 unique specimens with varying tibial slopes (range, -7.7° to 7.7°) through drop vertical jump and sidestep cutting tasks that were derived from 3-dimensional in vivo motion recordings. Internal knee joint torques and forces were recorded throughout simulation and were linearly correlated with tibial slope.. The mean (±SD) posterior tibial slope angle was 2.2° ± 4.3° in the lateral compartment and 2.3° ± 3.3° in the medial compartment. For simulated drop vertical jumps, lateral compartment tibial slope angle expressed moderate, direct correlations with peak internally generated knee adduction (r = 0.60-0.65), flexion (r = 0.64-0.66), lateral (r = 0.57-0.69), and external rotation torques (r = 0.47-0.72) as well as inverse correlations with peak abduction (r = -0.42 to -0.61) and internal rotation torques (r = -0.39 to -0.79). Only frontal plane torques were correlated during sidestep cutting simulations. For simulated drop vertical jumps, medial compartment tibial slope angle expressed moderate, direct correlations with peak internally generated knee flexion torque (r = 0.64-0.69) and lateral knee force (r = 0.55-0.74) as well as inverse correlations with peak external torque (r = -0.34 to -0.67) and medial knee force (r = -0.58 to -0.59). These moderate correlations were also present during simulated sidestep cutting.. The investigation supported the theory that increased posterior tibial slope would lead to greater magnitude knee joint moments, specifically, internally generated knee adduction and flexion torques.. The knee torques that positively correlated with increased tibial slope angle in this investigation are associated with heightened risk of ACL injury. Therefore, the present data indicated that a higher posterior tibial slope is correlated to increased knee loads that are associated with heightened risk of ACL injury.

Topics: Adult; Anterior Cruciate Ligament Injuries; Athletic Injuries; Biomechanical Phenomena; Cadaver; Female; Humans; Knee Joint; Male; Range of Motion, Articular; Risk Factors; Robotics; Rotation; Tibia; Torque; Young Adult

The optimal scheduling of Nordic Hamstring exercises (NHEs) relative to football training sessions is unknown. We examined the acute neuromuscular and performance responses to NHE undertaken either before (BT) or after (AT) simulated football training. Twelve amateur players performed six sets of five repetitions of the NHE either before or after 60 min of standardised football-specific exercise (SAFT

Topics: Adolescent; Adult; Athletic Injuries; Athletic Performance; Electromyography; Football; Hamstring Muscles; Humans; Knee; Knee Joint; Male; Muscle Fatigue; Muscle, Skeletal; Range of Motion, Articular; Resistance Training; Risk Factors; Running; Soccer; Torque; Young Adult

To compare the hip, knee and ankle torques, as well as knee and ankle flexibility between athletes with patellar tendinopathy and asymptomatic controls.. Cross-sectional study.. Laboratory setting.. Fourteen male volleyball, basketball or handball athletes, divided into 2 groups, patellar tendinopathy group (TG; n = 7) and asymptomatic control group (CG; n = 7).. Hip, knee and ankle isometric torques were measured with a handheld dynamometer. Weight-bearing ankle dorsiflexion, hamstring and quadriceps flexibility were measured with a gravity inclinometer.. The TG had 27% lower hip extensor torque when compared to the CG (P = 0.031), with no group differences in knee and ankle torques (P > 0.05). Also, the TG had smaller weight-bearing ankle dorsiflexion (P = 0.038) and hamstring flexibility (P = 0.006) when compared to the CG. Regarding quadriceps flexibility, no group differences were found (P = 0.828).. Strength and flexibility deficits might contribute to a greater overload on the knee extensor mechanism, possibly contributing to the origin/perpetuation of patellar tendinopathy. Interventions aiming at increasing hip extensors strength as well as ankle and knee flexibility might be important for the rehabilitation of athletes with patellar tendinopathy.

Topics: Adolescent; Adult; Athletic Injuries; Basketball; Biomechanical Phenomena; Cross-Sectional Studies; Humans; Isometric Contraction; Lower Extremity; Male; Muscle Strength; Muscle Strength Dynamometer; Patella; Range of Motion, Articular; Tendinopathy; Torque; Volleyball; Weight-Bearing

Evaluate the relationship of hip and trunk muscle function with the Single Leg Step-Down test (SLSD).. Laboratory study.. Biomechanics Laboratory.. 71 healthy participants with no history of anterior cruciate ligament (ACL) or lower extremity injury in the last 3 months completed this study (38 males, 33 females; mean 25.49 ± 0.62 years).. Hip abduction (HABD), external rotation (HER), and extension (HEXT) peak isometric force were measured. Trunk endurance was measured with plank (PL) and side plank (SPL) tests. SLSD repetitions in 60-s and dynamic knee valgus (VAL) were recorded.. PL, SPL, HABD, HER, and HEXT were positively correlated with SLSD repetitions. PL (r = 0.598, p < 0.001) was most correlated with SLSD repetitions, and regression demonstrated that PL (p = 0.001, R. Hip and trunk muscle function were positively correlated with SLSD performance, and these relationships were strongest in females. PL predicted performance on the SLSD. Further research is needed to investigate the utility of SLSD as a screening or return-to-play test for lower extremity conditions such as ACL injury and patellofemoral pain.

Topics: Adult; Athletic Injuries; Biomechanical Phenomena; Female; Healthy Volunteers; Hip Joint; Humans; Lower Extremity; Male; Muscle Strength; Physical Endurance; Return to Sport; Rotation; Sex Factors; Thorax; Torque

Fatigue-induced alterations in foot mechanics may lead to structural overload and injury.. To investigate how a high-intensity running exercise to exhaustion modifies ankle plantar-flexor and dorsiflexor strength and fatigability, as well as plantar-pressure distribution in adolescent runners.. Controlled laboratory study.. Academy research laboratory.. Eleven male adolescent distance runners (age = 16.9 ± 2.0 years, height = 170.6 ± 10.9 cm, mass = 54.6 ± 8.6 kg) were tested.. All participants performed an exhausting run on a treadmill. An isokinetic plantar-flexor and dorsiflexor maximal-strength test and a fatigue test were performed before and after the exhausting run. Plantar-pressure distribution was assessed at the beginning and end of the exhausting run.. We recorded plantar-flexor and dorsiflexor peak torques and calculated the fatigue index. Plantar-pressure measurements were recorded 1 minute after the start of the run and before exhaustion. Plantar variables (ie, mean area, contact time, mean pressure, relative load) were determined for 9 selected regions.. Isokinetic peak torques were similar before and after the run in both muscle groups, whereas the fatigue index increased in plantar flexion (28.1%; P = .01) but not in dorsiflexion. For the whole foot, mean pressure decreased from 1 minute to the end (-3.4%; P = .003); however, mean area (9.5%; P = .005) and relative load (7.2%; P = .009) increased under the medial midfoot, and contact time increased under the central forefoot (8.3%; P = .01) and the lesser toes (8.9%; P = .008).. Fatigue resistance in the plantar flexors declined after a high-intensity running bout performed by adolescent male distance runners. This phenomenon was associated with increased loading under the medial arch in the fatigued state but without any excessive pronation.

Topics: Adolescent; Ankle Injuries; Ankle Joint; Athletic Injuries; Exercise Test; Humans; Male; Muscle Fatigue; Pressure; Pronation; Running; Sprains and Strains; Torque

Hamstring injury-risk assessment has primarily been investigated using isokinetic dynamometry. However, practical issues such as cost and availability limit the widespread application of isokinetics for injury-risk assessment; thus, field-based alternatives for assessing eccentric hamstring strength are needed.. The aim of this study was to investigate the validity of the angle achieved during Nordic hamstring lowers (break-point angle) as a field-based test for eccentric hamstring strength.. Exploratory study.. Laboratory.. Sixteen male (n = 7) and female (n = 9) soccer players (mean ± SD age 24 ± 6 y, height 1.77 ± 0.12 m, and body mass 68.5 ± 16.5 kg) acted as subjects for the study.. The authors explored relationships between the Nordic break-point angle (the point at which the subject can no longer resist the increasing gravitational moment during a Nordic hamstring lower) measured from video and isokinetic peak torque and angle of peak torque of right- and left-knee flexors.. The results revealed a meaningful relationship between eccentric knee-flexor peak torque (average of right and left limbs) and the Nordic break-point angle (r = -.808, r2 = 65%, P < .00001). However, there was a weak relationship observed (r = .480, r2 = 23%, P = .06) between break-point angle and the angle of peak torque (average of right and left limbs).. The results suggest that the break-point angle achieved during Nordic hamstring lowers could be used as a field-based assessment of eccentric hamstring strength.

Topics: Athletic Injuries; Cross-Sectional Studies; Female; Humans; Male; Muscle Strength; Muscle, Skeletal; Risk Assessment; Soccer; Thigh; Torque; Video Recording; Young Adult

Return to activity in the presence of quadriceps dysfunction may predispose individuals with anterior cruciate ligament reconstruction (ACLR) to long-term joint degeneration. Asymmetry may manifest during movement and result in altered knee-joint-loading patterns; however, the underlying neurophysiologic mechanisms remain unclear.. To compare limb symmetry of quadriceps neuromuscular function between participants with ACLR and participants serving as healthy controls.. Descriptive laboratory study.. Research laboratory.. A total of 22 individuals with ACLR (12 men, 10 women) and 24 individuals serving as healthy controls (12 men, 12 women).. Normalized knee-extension maximal voluntary isometric contraction (MVIC) torque (Nm/kg), quadriceps central activation ratio (CAR) (%), quadriceps motor-neuron-pool excitability (Hoffmann reflex to motor wave ratio), and quadriceps active motor threshold (AMT) (% 2.0 T) were measured bilaterally and used to calculate limb symmetry indices for comparison between groups. We used analyses of variance to compare quadriceps Hoffmann reflex to motor wave ratio, normalized knee-extension MVIC torque, quadriceps CAR, and quadriceps AMT between groups and limbs.. The ACLR group exhibited greater asymmetry in knee-extension MVIC torque (ACLR group = 0.85 ± 0.21, healthy group = 0.97 ± 0.14; t44 = 2.26, P = .03), quadriceps CAR (ACLR group = 0.94 ± 0.11, healthy group = 1.00 ± 0.08; t44 = 2.22, P = .04), and quadriceps AMT (ACLR group = 1.13 ± 0.18, healthy group = 1.02 ± 0.11; t34 = -2.46, P = .04) than the healthy control group.. Asymmetries in measures of quadriceps function and cortical excitability were present in patients with ACLR. Asymmetry in quadriceps strength, activation, and cortical excitability persisted in individuals with ACLR beyond return to recreational activity. Measuring the magnitude of asymmetry after ACLR represents an important step in understanding long-term reductions in self-reported function and increased rate of subsequent joint injury in otherwise healthy, active individuals after ACLR.

Topics: Adolescent; Adult; Anterior Cruciate Ligament; Anterior Cruciate Ligament Injuries; Anterior Cruciate Ligament Reconstruction; Athletic Injuries; Female; Humans; Isometric Contraction; Knee Joint; Male; Muscle Weakness; Postoperative Complications; Psychomotor Performance; Quadriceps Muscle; Torque

Throwing a baseball is a dynamic and violent act that places large magnitudes of stress on the shoulder and elbow. Specific injuries at the elbow and glenohumeral joints have been linked to several kinetic variables throughout the throwing motion. However, very little research has directly examined the relationship between these kinetic variables and ball velocity.. To examine the correlation of peak ball velocity with elbow-valgus torque, shoulder external-rotation torque, and shoulder-distraction force in a group of collegiate baseball pitchers.. Cross-sectional study.. Motion-analysis laboratory.. Sixty-seven asymptomatic National Collegiate Athletic Association Division I baseball pitchers (age = 19.5 ± 1.2 years, height = 186.2 ± 5.7 cm, mass = 86.7 ± 7.0 kg; 48 right handed, 19 left handed).. We measured peak ball velocity using a radar gun and shoulder and elbow kinetics of the throwing arm using 8 electronically synchronized, high-speed digital cameras. We placed 26 reflective markers on anatomical landmarks of each participant to track 3-dimensional coordinate data. The average data from the 3 highest-velocity fastballs thrown for strikes were used for data analysis. We calculated a Pearson correlation coefficient to determine the associations between ball velocity and peak elbow-valgus torque, shoulder-distraction force, and shoulder external-rotation torque (P < .05).. A weak positive correlation was found between ball velocity and shoulder-distraction force (r = 0.257; 95% confidence interval [CI] = 0.02, 0.47; r(2) = 0.066; P = .018). However, no significant correlations were noted between ball velocity and elbow-valgus torque (r = 0.199; 95% CI = -0.043, 0.419; r(2) = 0.040; P = .053) or shoulder external-rotation torque (r = 0.097; 95% CI = -0.147, 0.329; r(2) = 0.009; P = .217).. Although a weak positive correlation was present between ball velocity and shoulder-distraction force, no significant association was seen between ball velocity and elbow-valgus torque or shoulder external-rotation torque. Therefore, other factors, such as improper pitching mechanics, may contribute more to increases in joint kinetics than peak ball velocity.

Topics: Athletic Injuries; Baseball; Biomechanical Phenomena; Cross-Sectional Studies; Elbow Joint; Humans; Kinetics; Male; Rotation; Shoulder Injuries; Shoulder Joint; Torque; Universities; Young Adult

Individuals with a history of anterior cruciate ligament reconstruction (ACLR) are at greater risk of reinjury and developing early-onset osteoarthritis due to persistent abnormal joint loading. Real-time clinical assessment tools may help identify patients experiencing abnormal movement patterns after ACLR.. To compare performance on the Landing Error Scoring System (LESS) between participants with ACLR and uninjured control participants and to determine the relationship between LESS score and knee-extension strength in these participants.. Controlled laboratory study.. Research laboratory.. Forty-six recreationally active participants, consisting of 22 with ACLR (12 men, 10 women; age = 22.5 ± 5.0 years, height = 172.8 ± 7.2 cm, mass = 74.2 ± 15.6 kg, body mass index = 24.6 ± 4.0) and 24 healthy control participants (12 men, 12 women; age = 21.7 ± 3.6 years, height = 168.0 ± 8.8 cm, mass = 69.2 ± 13.6 kg, body mass index = 24.3 ± 3.2) were enrolled.. Bilateral normalized knee-extension maximal voluntary isometric contraction (MVIC) torque (Nm/kg) and LESS scores were measured during a single testing session. We compared LESS scores between groups using a Mann-Whitney U test and the relationships between LESS scores and normalized knee-extension MVIC torque using Spearman ρ bivariate correlations.. The ACLR participants had a greater number of LESS errors (6.0 ± 3.6) than healthy control participants (2.8 ± 2.2; t44 = -3.73, P = .002). In ACLR participants, lower normalized knee-extension MVIC torque in the injured limb (ρ = -0.455, P = .03) was associated with a greater number of landing errors.. Participants with ACLR displayed more errors while landing. The occurrence of landing errors was negatively correlated with knee-extension strength, suggesting that weaker participants had more landing errors. Persistent quadriceps weakness commonly associated with ACLR may be related to a reduced quality of lower extremity movement during dynamic tasks.

Topics: Anterior Cruciate Ligament; Anterior Cruciate Ligament Injuries; Anterior Cruciate Ligament Reconstruction; Athletic Injuries; Biomechanical Phenomena; Case-Control Studies; Female; Humans; Isometric Contraction; Knee Injuries; Knee Joint; Male; Movement; Muscle Strength; Postoperative Period; Quadriceps Muscle; Torque; Young Adult

An objective assessment of quadriceps strength after anterior cruciate ligament reconstruction (ACLR) is an important clinical measure to determine readiness to return to sport (RTS). Not all clinicians are equipped with the means to objectively quantify quadriceps strength limb symmetry indices (Q-LSIs) via lower extremity isokinetic dynamometers, as recommended by previous studies.. The purpose of this study was to determine whether the International Knee Documentation Committee 2000 Subjective Knee Form (IKDC) score at time of RTS was a predictor of quadriceps strength in a young, athletic population after ACLR. Two hypotheses were tested: (1) Individuals with higher self-reports of function would demonstrate better quadriceps strength of the involved limb than individuals with lower self-reports of function at the time of RTS, and (2) individuals with higher self-reports of function would have normal quadriceps strength limb symmetry.. Cohort study (diagnosis); Level of evidence, 2.. At time of RTS, 139 subjects who had undergone ACLR completed the IKDC. In addition, an isometric quadriceps strength test (Biodex dynamometer) was performed on both lower extremities. Peak torques were calculated, as was the Q-LSI, determined by the formula (involved limb peak torque/uninvolved limb peak torque) × 100%. Participants were dichotomized based on IKDC scores: high IKDC (IKDC ≥90) and low IKDC (IKDC <90). Two-way analysis of variance was used to determine the effect of limb (involved vs uninvolved) and group (high vs low IKDC) on isometric quadriceps strength. Chi-square and logistic regression analyses were then performed to determine whether IKDC scores could predict Q-LSI.. At time of RTS, a significant correlation between IKDC scores and (1) peak isometric torque (r = 0.282, P < .001) and (2) Q-LSI (r = 0.357, P < .001) was observed. Individuals with IKDC scores ≥90 were 3 times (OR = 3.4; 95% CI, 1.71-6.93) more likely to demonstrate higher Q-LSI (≥90%). An IKDC score ≥94.8 predicted Q-LSI ≥90% with high sensitivity (0.813) and moderate specificity (0.493).. Participants with higher IKDC scores demonstrated an increased likelihood of presenting with greater involved limb quadriceps strength and better Q-LSI. Based on the results of this study, a patient-reported outcome measure, such as the IKDC, may be able to serve as a valuable screening tool for the identification of quadriceps strength deficits in this population; however, it should not be considered an accurate surrogate for isokinetic dynamometry. Furthermore, a score of ≥94.8 on the IKDC is likely to indicate that a patient's quadriceps strength is at an acceptable RTS level.

Topics: Adolescent; Adult; Anterior Cruciate Ligament; Anterior Cruciate Ligament Injuries; Anterior Cruciate Ligament Reconstruction; Athletic Injuries; Child; Female; Humans; Knee Injuries; Knee Joint; Longitudinal Studies; Lower Extremity; Male; Muscle Strength; Quadriceps Muscle; Return to Sport; Self Report; Torque; Young Adult

Several facets of figure skating, such as the forces associated with jumping and landing, have been evaluated, but a comprehensive biomechanical understanding of the cranial forces associated with spinning has yet to be explored. The purpose of this case study was to quantify the cranial rotational acceleration forces generated during spinning elements. This case report was an observational, biomechanical analysis of a healthy, senior-level, female figure skating athlete who is part of an on-going study. A triaxial accelerometer recorded the gravitational forces (G) during seven different spinning elements. Our results found that the layback spin generated significant cranial force and these forces were greater than any of the other spin elements recorded. These forces led to physical findings of ruptured capillaries, dizziness, and headaches in our participant.

Topics: Accelerometry; Athletic Injuries; Biomechanical Phenomena; Capillaries; Conjunctiva; Craniocerebral Trauma; Dizziness; Female; Headache; Humans; Skating; Sports Medicine; Torque; Young Adult

Osteitis pubis refers to a painful, inflammatory condition involving the pubic bones, pubic symphysis, and adjacent structures. So, the aims of the study were to evaluate the strength of trunk muscles of soccer players suffering from osteitis pubis, and to compare the agonist/antagonist ratio of trunk muscles in osteitis pubis athletes with that of healthy athletes.. Twenty-five soccer male athletes with osteitis pubis, and 25 healthy soccer athletes. Peak torque/body weight (PT/BW) was recorded from trunk muscles during isokinetic concentric and eccentric contraction modes at a speed of 120°/s for healthy and osteitis pubis soccer players.. There was a significant decrease in concentric contraction of back muscles in osteitis pubis group (p=0.01). A significant decrease in eccentric contraction of abdominal muscles was also recorded in osteitis pubis group (p=0.008). Concentric abdominal/back muscles ratio was significantly higher in osteitis pubis group (p=0.016), with no significant difference in eccentric abdominal/back muscles ratio between both groups (p>0.05).. Osteitis pubis group displayed concentric weakness of back muscle and eccentric weakness of abdominal muscles that lead to disturbance of the normal concentric abdominal/back ratio.

Topics: Abdominal Muscles; Adolescent; Athletes; Athletic Injuries; Back Muscles; Biomechanical Phenomena; Humans; Male; Muscle Contraction; Muscle Weakness; Osteitis; Pubic Bone; Pubic Symphysis; Soccer; Torque; Torso; Young Adult

This study aimed to examine the acute effects of dynamic stretching on concentric leg extensor and flexor peak torque, eccentric leg flexor peak torque, and the conventional and functional hamstring-quadriceps (H:Q) ratios.. Twenty-one women (mean ± SD age = 20.6 ± 2.0 yr, body mass = 64.5 ± 9.3 kg, height = 164.7 ± 6.5 cm) performed maximal voluntary isokinetic leg extension, flexion, and eccentric hamstring muscle actions at the angular velocities of 60°·s and 180°·s before and after a bout of dynamic hamstring and quadriceps stretching as well as a control condition.. Leg flexion peak torque decreased under both control (mean ± SE for 60°s = 75.8 ± 4.0 to 72.4 ± 3.7 N·m, 180°·s = 62.1 ± 3.2 to 59.1 ± 3.1 N·m) and stretching (60°·s = 73.1 ± 3.9 to 65.8 ± 3.3 N·m, 180°·s = 61.2 ± 3.3 to 54.7 ± 2.6 N·m) conditions, whereas eccentric hamstring peak torque decreased only after the stretching (60°·s = 87.3 ± 5.1 to 73.3 ± 3.6 N·m, 180°·s = 89.2 ± 4.4 to 77.0 ± 3.4 N·m) intervention (P ≤ 0.05). Stretching also caused a decrease in conventional H:Q (60°·s = 0.58 ± 0.02 to 0.54 ± 0.02, 180°·s = 0.67 ± 0.02 to 0.61 ± 0.03) and functional H:Q ratios (60°·s = 0.69 ± 0.03 to 0.60 ± 0.03, 180°·s = 1.00 ± 0.06 to 0.60 ± 0.03) (P ≤ 0.05).. Because dynamic stretching reduced concentric and eccentric hamstring strength as well as the conventional and functional H:Q ratios, fitness and allied-health professionals may need to be cautious when recommending dynamic rather than static stretching to maintain muscle force.

Topics: Adolescent; Athletic Injuries; Female; Humans; Muscle Strength; Muscle Stretching Exercises; Muscle, Skeletal; Quadriceps Muscle; Thigh; Torque; Young Adult

To investigate shoulder rotator strength and steadiness in athletes with anterior instability and superior labrum anterior posterior (SLAP) lesion.. Cross-sectional laboratory study.. Athletes with anterior shoulder instability (instability group, n=10) and a SLAP lesion (SLAP group, n=10) were compared with healthy athletes matched by age, anthropometrics and sport (control group for shoulder instability, n=10 and control group for SLAP, n=10). Torque steadiness was evaluated with three 10s submaximal isometric contractions (35% of peak torque) with the arm at 90° of shoulder abduction and 90° of external rotation. The mean isometric torque, standard deviation and coefficient of variation were measured from the steadiness trials. To evaluate shoulder rotator strength, concentric isokinetic tests (90°/s, 180°/s) were performed at the 90-90° position and peak torque to body mass and shoulder external to internal rotation ratio variables were analyzed. The variables were tested with the instability and control groups with respect to shoulder instability and between the SLAP and control groups for SLAP lesion using the Mann-Whitney test.. The SLAP group presented a higher coefficient of variation than the SLAP control group (p=0.003). Regarding shoulder strength, the internal and external shoulder rotators were weaker in the instability group than in the instability control group (p<0.05).. Athletes with anterior shoulder instability presented shoulder rotation weakness, while athletes with a SLAP lesion showed higher torque fluctuation during internal rotation. These results indicate that there are different alterations to strength and sensory motor control in each condition.

Topics: Adult; Athletic Injuries; Cross-Sectional Studies; Humans; Joint Instability; Ligaments, Articular; Muscle Contraction; Rotator Cuff; Shoulder Impingement Syndrome; Shoulder Joint; Torque; Young Adult

It has been suggested that noncontact anterior cruciate ligament injury commonly occurs during sports requiring acute deceleration or landing motion and that female athletes are more likely to sustain the injury than male athletes. The purpose of this study was to make task-to-task and male-female comparisons of knee kinematics and kinetics in several athletic activities. Three-dimensional knee kinematics and kinetics were investigated in 20 recreational athletes (10 males, 10 females) while performing hopping, cutting, turning, and sidestep and running (sharp deceleration associated with a change of direction). Knee kinematics and kinetics were compared among the four athletic tasks and between sexes. Subjects exhibited significantly lower peak flexion angle and higher peak extension moment in hopping compared with other activities (P < .05). In the frontal plane, peak abduction angle and peak adduction moment in cutting, turning, and sidestep and running were significantly greater compared with hopping (P < .05). No differences in knee kinematics and kinetics were apparent between male and female subjects. Recreational athletes exhibited different knee kinematics and kinetics in the four athletic motions, particularly in the sagittal and frontal planes. Male and female subjects demonstrated similar knee motions during the four athletic activities.

Topics: Acceleration; Adult; Anterior Cruciate Ligament; Anterior Cruciate Ligament Injuries; Athletic Injuries; Computer Simulation; Female; Humans; Knee Injuries; Knee Joint; Male; Models, Biological; Range of Motion, Articular; Risk Factors; Running; Torque

Non-contact injuries in soccer players may be related to the interplay between cleat type and playing surface, and bladed shoes were often blamed for non-contact injuries with no research support. The aim of this study was to compare the rotational resistance (stiffness and peak sustainable torque) among three types of soccer cleats (metal studs, molded rubber studs, and bladed) in a controlled laboratory environment. The shoes were tested on both natural and artificial turfs under a compressive preload of 1000 N and with internal and external rotations. The three shoe models showed comparable performances with a good repeatability for each individual test on both playing surfaces. A less stiff behavior was observed for the natural turf. A tendency toward highest peak torque was observed in the studded model on natural surface. The bladed cleats provided peak torque and rotational stiffness comparable to the other models. Studded and bladed cleats did not significantly differ in their interaction with the playing surface. Therefore, soccer shoes with bladed cleats should not be banned in the context of presumed higher risk for non-contact injuries.

Topics: Athletic Injuries; Equipment Design; Humans; Poaceae; Polyethylene; Rotation; Shoes; Soccer; Sports Equipment; Torque

The effect of prior strain injury on myoelectrical activity of the hamstrings during tasks requiring high rates of torque development has received little attention.. To determine if recreational athletes with a history of unilateral hamstring strain injury will exhibit lower levels of myoelectrical activity during eccentric contraction, rate of torque development (RTD), and impulse (IMP) at 30, 50, and 100 milliseconds after the onset of myoelectrical activity or torque development in the previously injured limb compared with the uninjured limb.. Case control study; Level of evidence, 3.. Twenty-six recreational athletes were recruited. Of these, 13 athletes had a history of unilateral hamstring strain injury (all confined to biceps femoris long head), and 13 had no history of hamstring strain injury. Following familiarization, all athletes undertook isokinetic dynamometry testing and surface electromyography (integrated EMG; iEMG) assessment of the biceps femoris long head and medial hamstrings during eccentric contractions at -60 and -180 deg·s(-1).. In the injured limb of the injured group, compared with the contralateral uninjured limb, RTD and IMP was lower during -60 deg·s(-1) eccentric contractions at 50 milliseconds (RTD: injured limb, 312.27 ± 191.78 N·m·s(-1) vs uninjured limb, 518.54 ± 172.81 N·m·s(-1), P = .008; IMP: injured limb, 0.73 ± 0.30 N·m·s vs uninjured limb, 0.97 ± 0.23 N·m·s, P = .005) and 100 milliseconds (RTD: injured limb, 280.03 ± 131.42 N·m·s(-1) vs uninjured limb, 460.54 ± 152.94 N·m·s(-1), P = .001; IMP: injured limb, 2.15 ± 0.89 N·m·s vs uninjured limb, 3.07 ± 0.63 N·m·s, P < .001) after the onset of contraction. Biceps femoris long head muscle activation was lower at 100 milliseconds at both contraction speeds (-60 deg·s(-1), normalized iEMG activity [×1000]: injured limb, 26.25 ± 10.11 vs uninjured limb, 33.57 ± 8.29, P = .009; -180 deg·s(-1), normalized iEMG activity [×1000]: injured limb, 31.16 ± 10.01 vs uninjured limb, 39.64 ± 8.36, P = .009). Medial hamstring activation did not differ between limbs in the injured group. Comparisons in the uninjured group showed no significant between limbs difference for any variables.. Previously injured hamstrings displayed lower RTD and IMP during slow maximal eccentric contraction compared with the contralateral uninjured limb. Lower myoelectrical activity was confined to the biceps femoris long head. Regardless of whether these deficits are the cause of or the result of injury, these findings could have important implications for hamstring strain injury and reinjury. Particularly, given the importance of high levels of muscle activity to bring about specific muscular adaptations, lower levels of myoelectrical activity may limit the adaptive response to rehabilitation interventions and suggest that greater attention be given to neural function of the knee flexors after hamstring strain injury.

Topics: Adult; Athletes; Athletic Injuries; Electromyography; Humans; Male; Muscle Contraction; Muscle, Skeletal; Torque; Young Adult

Jockey head injuries, especially concussions, are common in horse racing. Current helmets do help to reduce the severity and incidences of head injury, but the high concussion incidence rates suggest that there may be scope to improve the performance of equestrian helmets. Finite element simulations in ABAQUS/Explicit were used to model a realistic helmet model during standard helmeted rigid headform impacts and helmeted head model University College Dublin Brain Trauma Model (UCDBTM) impacts. Current helmet standards for impact determine helmet performance based solely on linear acceleration. Brain injury-related values (stress and strain) from the UCDBTM showed that a performance improvement based on linear acceleration does not imply the same improvement in head injury-related brain tissue loads. It is recommended that angular kinematics be considered in future equestrian helmet standards, as angular acceleration was seen to correlate with stress and strain in the brain.

Topics: Acceleration; Animals; Athletic Injuries; Brain Injuries; Computer Simulation; Computer-Aided Design; Craniocerebral Trauma; Equipment Design; Finite Element Analysis; Head Protective Devices; Horses; Humans; Models, Biological; Rotation; Sports Equipment; Stress, Mechanical; Torque; Wounds, Nonpenetrating

Throwing fractures of the humerus are well known, but the exact mechanism of injury is not clear. It has been postulated that these may be stress fractures because the forces have not seemed sufficient to cause acute fractures while throwing.. Using finite element analysis, we reproduced fractures of the humerus using 3-dimensional models built from computed tomography images of 5 healthy volunteers. To apply the load during throwing, we assumed that the humeral head was completely fixed, and external rotation torque was applied to the distal end of the humerus until the stress of the bone elements became greater than yield stress. We reproduced the fracture line by removing the bone elements.. The maximum stress concentration was seen in the distal shaft, where a typical spiral fracture was created in all cases. In the humeral models, the torque required to initiate fracture ranged from 51 to 70 Nm. A strong correlation existed between the torque required to initiate fracture and thickness of the humeral cortical bone (R(2) = 0.74).. These results indicate that thickness of the humerus represents one factor contributing to fractures that occur while throwing.. Basic science study.

Topics: Athletic Injuries; Biomechanical Phenomena; Computer Simulation; Finite Element Analysis; Humans; Humeral Fractures; Male; Stress, Mechanical; Tensile Strength; Tomography, X-Ray Computed; Torque; Young Adult

Elbow injuries are widely reported among baseball players. The elbow is susceptible to injury when elbow-flexor and -extensor forces are imbalanced during pitching or throwing. Assessment of muscle-strength ratios may prove useful for diagnosing elbow injury.. The purpose of this study was to assess the relationship between the elbow-flexor and -extensor functional isokinetic ratios and elbow injury in baseball players.. Retrospective study.. Biomechanics laboratory.. College baseball players with (n = 9) and without (n = 12) self-reported elbow pain or loss of strength were recruited.. Trials were conducted using a dynamometer to assess dominant-arm flexor and extensor concentric and eccentric strength at angular velocities of 60 degrees and 240 degrees/s. Functional isokinetic ratios were calculated and compared between groups.. Regression analysis revealed that a ratio of biceps concentric to triceps concentric strength greater than 0.76 (the median value) significantly predicted elbow injury (P = .01, odds ratio of injury = 24). No other ratios or variables (including position played) were predictive of injury status.. These findings suggest that the ratio of biceps concentric to triceps concentric functional strength strongly predicts elbow-injury status in baseball players. Assessment of this ratio may prove useful in a practical setting for training purposes and both injury diagnosis and rehabilitation.

Topics: Athletic Injuries; Baseball; Biomechanical Phenomena; Elbow Injuries; Humans; Logistic Models; Male; Multivariate Analysis; Muscle Contraction; Muscle Strength; Muscle Strength Dynamometer; Muscle, Skeletal; Posture; Regression Analysis; Retrospective Studies; Risk Factors; Taiwan; Torque; Young Adult

The prevalence of sustaining a sport injury is high in adults. Deficits in postural control/muscle strength represent important injury-risk factors. Thus, the purpose of this study was to investigate the impact of a specific type of balance training, i. e. slackline training, followed by detraining on balance and strength performance. Twenty-seven adults participated in this study and were assigned to an intervention (age 22.8±3.3 yrs) or a control group (age 23.9±4.4 yrs). The intervention group participated in 4 weeks of slackline training on nylon webbings. Detraining lasted 4 weeks. Tests included the measurement of (A) total centre of pressure displacements during one-legged standing on a balance platform and during the compensation of a perturbation impulse, (B) maximal torque and rate of force development (RFD) of the plantar flexors on an isokinetic device, and (C) jumping height on a force platform. After training, no significant interaction effects were observed for variables of static/dynamic postural control, maximal torque, and jumping height. Training-induced improvements were found for RFD. After the withdrawal of the training stimulus, RFD slightly decreased. Given that the promotion of balance and strength is important for injury prevention, changes in RFD only might not be sufficient to produce an injury-preventive effect.

Topics: Adult; Athletic Injuries; Female; Humans; Leg; Male; Movement; Muscle Strength; Physical Education and Training; Postural Balance; Torque; Young Adult

Previous studies have documented increased posteromedial contact forces with the elbow at lower flexion angles associated with valgus extension overload; however, the authors believe that posteromedial elbow impingement in association with valgus laxity is a complex pathological process that may occur throughout the entire throwing motion in the form of ulnohumeral chondral and ligamentous overload.. Valgus laxity with the elbow at 90° of flexion may lead to chondromalacia secondary to a subtle shift in the contact point between the tip of the olecranon and the distal humeral trochlea.. Controlled laboratory study.. Six fresh human cadaveric elbows were dissected and subjected to a static valgus load. Pressure-sensitive Fuji film measured the contact pressure, contact area, and shift in contact area across the posteromedial elbow before and after sectioning the anterior bundle of the ulnar collateral ligament.. The contact pressure between the tip of the olecranon process and the medial crista of the posterior humeral trochlea significantly increased, from an average of 0.27 ± 0.06 kg/cm² to 0.40 ± 0.08 kg/cm². The contact area also significantly decreased, from an average of 30.34 ± 9.17 mm² to 24.59 ± 6.44 mm², and shifted medially on the medial humeral crista, which corresponds to the position of the posteromedial chondral lesions that was observed in throwing athletes in the authors' clinical practice.. While simulating the early acceleration phase of the throwing motion with the elbow in 90° of flexion, the results illustrate that abnormal contact may occur as a result of valgus laxity through increased contact pressures across the posteromedial elbow between the medial tip of the olecranon and medial crista of the humeral trochlea. In addition, congruency of the ulnohumeral joint changed, as there was a statistically significant medial shift of the olecranon on the posterior humeral trochlea with the elbow at 90° of flexion after sectioning the anterior bundle of the ulnar collateral ligament.. In the throwing athlete who continues the repetitive, throwing motion despite valgus laxity from ulnar collateral ligament insufficiency, the authors believe that these results provide a plausible mechanism for injury throughout the entire throwing motion secondary to ulnohumeral chondral and ligamentous overload. As throwing athletes may produce a tremendous amount of force and subsequent chondromalacia within the posteromedial aspect of the elbow, the findings of this study illustrate the importance of prompt clinical recognition of ulnar collateral ligament insufficiency.

Topics: Athletic Injuries; Biomechanical Phenomena; Cadaver; Cartilage Diseases; Chondrocytes; Humans; Humerus; Olecranon Process; Torque; Ulna

The purpose of this study was to monitor the muscular changes regarding the isokinetic strength and torque pattern of the quadriceps femoris at the stable athlete's knee after meniscus tear refixation.. Therefore 15 athletes (10 male, 5 female) performing recreational or competitional sports at least five times a week before injury were retrospectively examined in the average 2.5 years after isolated arthroscopic meniscus refixation using Inside Out technique. Next to function and sport activity focused scores the isokinetic peak torque (PT) and in the EMG have been analyzed compared to the uninjured knee.. The mean age was 31.26 years. The time between injury and surgery was in the average 13.7 days. According to our first results the data suggest a complete recovery of functional and muscular pattern after meniscus refixation at the stable athlete's knee. No significant EMG changes for quadriceps femoris were detectable. The PT was fully recovered. The functional and sport activity score analysis (Lysholm and Tegner score) showed no changes in the postoperative long-term follow up compared to the preinjured status.. Examining isokinetic PT and the EMG of the quadriceps femoris, these data show no side-to-side differences. Regarding the function and sports activity score system, the functionally high demand patients seem to profit by this procedure.

Topics: Adult; Arthroscopy; Athletic Injuries; Biomechanical Phenomena; Female; Humans; Knee Joint; Male; Menisci, Tibial; Middle Aged; Muscle Strength; Quadriceps Muscle; Recovery of Function; Retrospective Studies; Tibial Meniscus Injuries; Torque; Treatment Outcome; Young Adult

The aim of this study was to compare within-individual variability in baseball pitching among various levels of competition. It was hypothesized that variability decreases as level of competition increases. Five fastballs were analysed for 93 healthy male baseball pitchers (20 youth, 19 high school, 20 college, 20 Minor League, and 14 Major League level pitchers). Eleven kinematic, four temporal, and six kinetic parameters were quantified with a 240-Hz automated digitizing system. Three multiple analyses of variance were used to compare individual standard deviations for kinematic, temporal, and kinetic parameters among the five competition levels. There was a significant overall difference in kinematics and in six of the eleven kinematic parameters analysed: foot placement, knee flexion, pelvis angular velocity, elbow flexion, shoulder external rotation, and trunk forward tilt. Individual standard deviations tended to be greatest for youth pitchers, and decreased for higher levels of competition. Thus pitchers who advanced to higher levels exhibited less variability in their motions. Differences in temporal variation were non-significant; thus variability in pitching coordination was not improved at higher levels. Differences in kinetic variation were non-significant, implying no particular skill level has increased risk of injury due to variation in joint kinetics.

Topics: Acceleration; Adolescent; Adult; Athletic Injuries; Baseball; Biomechanical Phenomena; Child; Competitive Behavior; Elbow Joint; Humans; Male; Pelvis; Shoulder Injuries; Shoulder Joint; Task Performance and Analysis; Torque; Young Adult

The purpose of this study was to examine the effects of posterior thigh and leg stretching on leg flexion peak torque (PT), leg extension PT, the hamstrings-to-quadriceps (H:Q) ratio, and electromyographic (EMG) amplitude of the hamstrings and quadriceps in recreationally-active men.. Fifteen men (mean age + or - SD = 22.0 + or - 4.4 years; body mass = 82.7 + or - 16.1 kg; height = 173.1 + or - 6.8 cm) performed three maximal voluntary concentric isokinetic leg extension and flexion muscle actions at three randomly ordered angular velocities (60, 180, and 300 degrees x s(-1)) before and after hamstring and calf static stretching. The stretching protocol consisted of 1 unassisted and 3 assisted static stretching exercises designed to stretch the posterior muscles of the thigh and leg. Four repetitions of each stretch were held for 30 s with 20-s rest between repetitions.. These findings indicated no significant (P>0.05) stretching-induced changes in leg flexion PT, leg extension PT, or EMG amplitude at 60, 180, or 300 degrees .s-1. However, the non-significant (P>0.05) 2-4% increases in leg extension PT combined with the non-significant (P>0.05) 1-2% decreases in leg flexion PT resulted in the significant (P < or = 0.05) 2-9% decreases in the H:Q ratio from pre- to post-stretching for all three velocities.. These findings suggested that static stretching of the hamstrings and calf muscles may decrease the H:Q ratio. These results may be useful for athletic trainers, physical therapists, and other allied health professionals who may use the H:Q ratio as a clinical assessment.

Topics: Analysis of Variance; Athletic Injuries; Body Mass Index; Electromyography; Humans; Leg; Leg Injuries; Male; Muscle Contraction; Muscle Strength Dynamometer; Muscle Stretching Exercises; Muscle, Skeletal; Quadriceps Muscle; Risk Factors; Torque; Young Adult

evaluate the gotten results of the accelerated protocol adapted to the clinic conditions in CLA post operatory patients.. 30 patients were selected and submitted to an isokynetic test at the pre operatory and 4 months post operatory.. the isokinetics evaluations at the pre operatory presented: flexor peak torque 93% at 60 degrees /s and 97,3% at 180 degrees /s. Extensor 87,3% at 60 degrees /s and 94,7% at 180 degrees /s; power of the flexor muscles of 93,3% and extensors of 96,7%; the muscular work of the flexors was of 91,7% and extensors of 90,3%; the flexor peak torque angle was at 28,7 degrees . At the extensor musculature the angle was at 62,2 degrees ; flexors eccentric peak torque of 78,3% and the extensors of 12,8%. With 4 months of post operatory the gotten results showed: flexor peak torque 95,4% at 60 degrees /s and 97,1%. at 180 degrees /s; extensor 70% at 60 degrees /s and 75,7%. at 180 degrees /s; power of the flexor muscles of 97,1% and extensors of 79,8%; the muscular work of the flexors was of 94,2% and extensors of 94,2%; flexors eccentric peak torque of 84% and extensors of 24,2%; the flexor peak torque angle was at 27,3 degrees ; in extensor musculature the angle was at 61,7 degrees .. showed that the patients treated with the adapted protocol presented similar results to the original protocol in relation to the muscular conditions.

Topics: Adult; Anterior Cruciate Ligament; Anterior Cruciate Ligament Injuries; Athletic Injuries; Clinical Protocols; Humans; Knee Injuries; Male; Muscle Strength; Muscle Strength Dynamometer; Torque

Lower back injuries, specifically lumbar stress fractures, account for the most lost playing time in professional cricket. The aims of this study were to quantify the proportion of lower trunk motion used during the delivery stride of fast bowling and to examine the relationship between the current fast bowling action classification system and potentially injurious kinematics of the lower trunk. Three-dimensional kinematic data were collected from 50 male professional fast bowlers during a standing active range of motion trial and three fast bowling trials. A high percentage of the fast bowlers used a mixed bowling action attributable to having shoulder counter-rotation greater than 30 degrees. The greatest proportion of lower trunk extension (26%), contralateral side-flexion (129%), and ipsilateral rotation (79%) was used during the front foot contact phase of the fast bowling delivery stride. There was no significant difference in the proportions of available lower trunk extension, contralateral side-flexion, and ipsilateral rotation range of motion used during fast bowling by mixed and non-mixed action bowlers. Motion of the lower trunk, particularly side-flexion, during front foot contact, in addition to variables previously known to be related to back injury (e.g. shoulder counter-rotation), should be examined in future cross-sectional and prospective studies examining the fast bowling action and low back injury.

Topics: Adult; Athletic Injuries; Biomechanical Phenomena; Competitive Behavior; Cumulative Trauma Disorders; Fractures, Stress; Humans; Lumbar Vertebrae; Lumbosacral Region; Male; Movement; Torque; United Kingdom; Video Recording

The curveball has been anecdotally considered as a dangerous pitch among youth pitchers, especially for their ulnar collateral ligaments. No biomechanical studies have been conducted among youth pitchers comparing different types of pitches.. The kinetics of the baseball throw varies significantly between the fastball, curveball, and change-up for youth pitchers. Kinematic and temporal differences are also expected.. Controlled laboratory study.. Twenty-nine youth baseball pitchers (age, 12.5 +/- 1.7 years) pitched 5 fastballs, 5 curveballs, and 5 change-ups with maximum effort in an indoor laboratory setting. Data were collected with a 3-dimensional motion analysis system. Kinetic, kinematic, and temporal parameters were compared among the 3 pitches.. For elbow varus torque, shoulder internal rotation torque, elbow proximal force, and shoulder proximal force, the fastball produced the greatest values, followed by the curveball and then the change-up. The fastball also produced the greatest elbow flexion torque. Shoulder horizontal adduction torque and shoulder adduction torque were the least for the change-up. Several differences in body segment position, velocity, and timing were also found.. In general, elbow and shoulder loads were the greatest in the fastball and least in the change-up. Kinematic and temporal differences were also found among the 3 pitch types.. The curveball may not be more potentially harmful than the fastball for youth pitchers. This finding is consistent with recent epidemiologic research indicating that amount of pitching is a stronger risk factor than type of pitches thrown.

Topics: Adolescent; Arm Injuries; Athletic Injuries; Baseball; Biomechanical Phenomena; Child; Humans; Male; Risk Assessment; Torque; United States

Although several studies have investigated the acute effect of static stretching exercises, the duration of exercises that negatively affects performance has not been ascertained. This study was conducted to determine the acute effect of different static stretching durations on quadriceps isometric and isokinetic peak torque production. The 50 participants were randomly allocated into five equivalent sized groups and were asked to perform a stretching exercise of different duration (no stretch, 10-second stretch, 20-second stretch, 30-second stretch, and 60-second stretch). The knee flexion range of motion and the isometric and concentric isokinetic peak torques of the quadriceps were measured before and after a static stretching exercise in the four experimental groups. The same parameters were examined in the control group (no stretch) without stretching, before and after a 5-minute passive rest. There were no significant differences among groups before the experimentation regarding their physical characteristics and performances (P > 0.05). These results reflect the different groups' homogeneity. Significant knee joint flexibility increases (P < 0.001) and significant isometric and isokinetic peak torque reductions (P < 0.05-0.001) have been shown to occur only after 30 and 60 seconds of quadriceps static stretching. Stretching reduced isometric peak torque by 8.5% and 16.0%, respectively. Concerning isokinetic peak torque after 30 and 60 seconds of stretching, it was reduced by 5.5% vs. 11.6% at 60 degrees/s and by 5.8% vs. 10.0% at 180 degrees/s. We suggest that torque decrements are related to changes of muscle neuromechanical properties. It is recommended that static stretching exercises of a muscle group for more than 30 seconds of duration be avoided before performances requiring maximal strength.

Topics: Adult; Analysis of Variance; Athletic Injuries; Cohort Studies; Exercise Tolerance; Humans; Isometric Contraction; Knee Joint; Male; Muscle Contraction; Muscle Stretching Exercises; Physical Education and Training; Physical Exertion; Probability; Quadriceps Muscle; Range of Motion, Articular; Sensitivity and Specificity; Task Performance and Analysis; Time Factors; Torque

A decreased hamstring:quadriceps (H:Q) ratio may put the hamstrings and anterior cruciate ligament (ACL) at increased risk of injury. Therefore, the purpose of this study was to evaluate H:Q ratios of 12 female National Collegiate Athletic Association soccer players, and to test the effects of a 6-week strength training program on these ratios. Each subject completed 2 practice sessions before a pretest. Subjects then completed 6 weeks of strength training that included the addition of 2 hamstring specific exercises, followed by a posttest. Peak torque during concentric and eccentric actions for both hamstrings and quadriceps was measured with an isokinetic dynamometer. Each muscle action was tested at 3 angular velocities in the following order: concentric 240, 180, and 60 degrees x s(-1) and eccentric 60, 180, and 240 degrees x s(-1). The H:Q strength ratio was evaluated using concentric muscle actions (concentric hamstrings:concentric quadriceps). This method is commonly used and is thus called the conventional ratio. Because concentric actions do not occur simultaneously in opposing muscles, a more functional assessment compares eccentric hamstring actions to concentric quadriceps actions. This functional ratio was also analyzed. Mean conventional and functional H:Q ratio data were analyzed using separate analysis of variance procedures with repeated measures on all factors (2 [Test] x 2 [Leg] x 3 [Angular Velocity]). The results revealed a significant main effect for factor (F test) with the functional ratio (p < 0.05) but not for the conventional ratio. The mean functional ratio increased from 0.96 +/- 0.09 in pretest to 1.08 +/- 0.11 in posttest. These results suggest that 6 weeks of strength training that emphasizes hamstrings is sufficient to significantly increase the functional ratio. The functional ratio after training exceeded 1.0, which is specifically recommended for prevention of ACL injuries.

Topics: Adult; Athletic Injuries; Female; Humans; Leg; Muscle Strength; Muscle, Skeletal; Physical Education and Training; Quadriceps Muscle; Soccer; Torque

Repeated-measures experimental design.. To examine the acute effects of static stretching on peak torque, the joint angle at peak torque, mean power output, and electromyographic and mechanomyographic amplitudes and mean power frequency of the vastus lateralis and rectus femoris muscles during maximal eccentric isokinetic muscle actions.. A bout of static stretching may impair muscle strength during isometric and concentric muscle actions, but it is unclear how static stretching may affect eccentric force production.. Fifteen men (mean +/- SD age, 23.4 +/- 2.4 years) performed maximal eccentric isokinetic muscle actions of the dominant and nondominant knee extensor muscles at 60 degrees x s(-1) and 180 degrees x s(-1) on an isokinetic dynamometer, while electromyographic and mechanomyographic amplitudes (root-mean-square) and mean power frequency were calculated for the vastus lateralis and rectus femoris muscles. Peak torque (Nm), the joint angle at peak torque (degrees), and mean power output (W) values were recorded by the dynamometer. Subsequently, the dominant lower extremity knee extensors underwent static stretching exercises, then the assessments were repeated.. There were no stretching-related changes in peak torque, the joint angle at peak torque, mean power output, electromyographic or mechanomyographic amplitude, or mean power frequency (P > .05). However, there were expected velocity-related, limb-related, and muscle-related differences (P < or = .05) that were unrelated to the stretching intervention.. These results suggest that static stretching does not affect maximal eccentric isokinetic torque or power production, nor does it change muscle activation.

Topics: Adult; Athletic Injuries; Electromyography; Exercise; Humans; Knee Joint; Male; Muscle Strength; Muscle Stretching Exercises; Muscle, Skeletal; Range of Motion, Articular; Reproducibility of Results; Torque

This study investigated the clinical features of patellar tendinopathy (PT), with focus on individuals with unilateral and bilateral PT. A cross-sectional study design was employed to compare individuals with unilateral (n = 14) or bilateral (n = 13) PT and those without PT (control, n = 31). Features assessed included thigh strength (normalized peak knee extensor torque) and flexibility (sit-and-reach and active knee extension), calf endurance (heel-rise test), ankle flexibility (dorsiflexion), alignment measures (arch height and leg length difference), and functional measures (hop for distance and 6 m hop test). Groups were matched for age and height; however, unilateral and bilateral PT had greater mass with a higher body mass index (BMI) than control. Also, bilateral PT performed more sport hours per week than both unilateral PT and control. Unilateral PT had less thigh strength than control and bilateral PT, whereas bilateral PT had more thigh flexibility than control and unilateral PT. Both unilateral and bilateral PT had altered alignment measures compared to control. Features that predicted symptoms in PT were lower thigh flexibility and strength, whereas those that predicted function were higher thigh strength and lower ankle flexibility. These findings indicate that unilateral and bilateral PT represent distinct entities, and that thigh strength appears particularly important in PT as it predicted both symptoms and function in PT.

Topics: Adolescent; Adult; Athletic Injuries; Cross-Sectional Studies; Exercise Test; Female; Humans; Lower Extremity; Male; Muscle Strength; Muscle, Skeletal; Patellar Ligament; Pliability; Reproducibility of Results; Sports Medicine; Tendinopathy; Thigh; Torque

This study set out to determine the incidence of ankle injuries amongst provincial female field hockey players in KwaZulu-Natal (KZN), South Africa, during the 2004 field hockey season and relate this to their injury and playing profile, proprioceptive ability and peak isokinetic torque of the ankle plantar and dorsiflexor muscles. Players participating in the senior, U21 and U19/high school provincial A teams (n=47) detailed their hockey playing and training history and injuries sustained during the 2004 season. A subsample of injured and matched, uninjured controls (n=18) underwent anthropometric, proprioceptive and isokinetic testing. Incidence of injury in the 2004 season was 0.98 per player or 6.32 injuries per 1000 player/h(-1), with 25.5% of players (n=12) reporting injuries to the ankle joint. All ankle injuries occurred on artificial turf and 75% occurred during a match. Forwards and links that had been playing for six to seven years presented with the highest incidence of ankle injuries. Injured players were able to maintain balance on a proprioceptive board for 10.31+/-8.2 s versus 23.9+/-15.3 s in matched, uninjured controls (p=0.078). Both mean (27.4+/-5.5 Nm versus 32.7+/-4.7 Nm) and median (27.0, 23.0-31.5 versus 31.8, 30.0-35.1 Nm) peak isokinetic torque of the dorsiflexors of injured legs was significantly lower than in uninjured, contralateral legs of the injured players (p=0.01 and 0.03, respectively). Poor peak dorsiflexion torque in the injured leg was identified as a factor associated with ankle injury in this sample of injured, elite field hockey players.

Topics: Adult; Ankle Injuries; Anthropometry; Athletic Injuries; Body Constitution; Female; Hockey; Humans; Incidence; Muscle Contraction; Muscle Strength; Muscle, Skeletal; Proprioception; Retrospective Studies; South Africa; Statistics, Nonparametric; Surveys and Questionnaires; Torque

The purposes of this study were (a) to determine whether a significant strength imbalance existed between the left and right or dominant (D) and nondominant (ND) legs and (b) to investigate possible correlations among various unilateral and bilateral closed kinetic chain tests, including a field test, and traditional isokinetic dynamometry used to determine strength imbalance. Fourteen Division I collegiate women softball players (20.2 +/- 1.4 years) volunteered to undergo measures of average peak torque for isokinetic flexion and extension at 60 degrees .s(-1) and 240 degrees .s(-1); in addition, measures of peak and average force of each leg during parallel back squat, 2-legged vertical jump, and single-leg vertical jump and performance in a 5-hop test were examined. Significant differences of between 4.2% and 16.0% were evident for all measures except for average force during single-leg vertical jump between the D and ND limbs, thus revealing a significant strength imbalance. The 5-hop test revealed a significant difference between D and ND limbs and showed a moderate correlation with more sophisticated laboratory tests, suggesting a potential use as a field test for the identification of strength imbalance. The results of this study indicate that a significant strength imbalance can exist even in collegiate level athletes, and future research should be conducted to determine how detrimental these imbalances could be in terms of peak performance for athletes, as well as the implications for injury risk.

Topics: Adult; Analysis of Variance; Athletic Injuries; Baseball; Biomechanical Phenomena; Female; Humans; Lower Extremity; Muscle Strength; Torque

Although the scar tissue, which heals the donor site defect, has different elasticity from the neighbouring patellar tissue, it remains unclear if this scar tissue can lead to the changes of the electromechanical delay (EMD) of the knee extensor muscles. If such changes do exist, they can possibly affect both the utilization of the stored energy in the series elastic component, as well as the optimal performance of the knee joint movement. The purpose of this study was to investigate the influence of harvesting the patellar tendon during anterior cruciate ligament (ACL) reconstruction and the associated patellar tendon scar tissue development on the EMD of the rectus femoris (RF) and vastus medialis (VM) muscles. Seventeen patients who underwent an ACL reconstruction using the medial third of the patellar tendon were divided in two groups based upon their post-operative time interval. Maximal voluntary contraction from the knee extensors, surface EMG activity, and ultrasonographic measurements of the patellar tendon cross-section area were obtained from both knees. Our results revealed that no significant changes for the maximal voluntary contraction of the knee extensors and for the EMD of the RF and the VM muscles due to patellar scar tissue development after harvesting the tendon for ACL reconstruction. The EMD, as a component of the stretch reflex, is important for the utilization of the stored energy in the series elastic component and thus, optimal sports performance. However, from our results, it can be implied that the ACL reconstruction using a patellar tendon graft would not impair sports performance as far as EMD is concerned.

Topics: Adult; Anterior Cruciate Ligament; Anterior Cruciate Ligament Injuries; Athletic Injuries; Electromyography; Humans; Muscle Contraction; Muscle, Skeletal; Patella; Reflex, Stretch; Tendons; Torque; Ultrasonography

Despite the higher incidence of anterior cruciate ligament (ACL) injuries in female than in male athletes few authors have studied the effects of gender on the outcome of ACL reconstruction. This prospective study compared the results of ACL reconstruction using the patellar tendon and hamstring techniques in men and women. We prospectively followed 80 comparable athletes (46 males, 32 females) from a population of 287 patients operated on at our institution for ACL reconstruction using either patellar tendon or hamstring graft. There were 26 males and 14 females in the patellar tendon group, and 22 males and 18 females in the hamstring group. All patients were operated on by the same surgeon within 6 months from injury and underwent the same rehabilitation program at the same center. After an average of 36 months the patients were assessed by clinical evaluation, computerized knee laxity analysis, and isokinetic and functional strength tests; standard knee scores were also used. Among patellar tendon patients there were no significant differences between males and females regarding knee evaluation form, laxity, or isokinetic and functional tests. Females in the hamstring group had significantly greater laxity, and isokinetic tests at 1 year revealed a significantly higher deficit of peak torque at 60 degrees /s in flexion and extension. We suggest further studies on the clinical significance of these findings particularly on their possible ramifications in the areas of return to sports and rehabilitation of female athletes.

Topics: Adult; Anterior Cruciate Ligament; Anterior Cruciate Ligament Injuries; Athletic Injuries; Biomechanical Phenomena; Female; Humans; Knee Injuries; Male; Muscle, Skeletal; Patellar Ligament; Prospective Studies; Statistics, Nonparametric; Tendons; Torque; Transplantation, Autologous; Treatment Outcome

To determine an ankle inversion-eversion movement range part where evertor/invertor muscles torque ratio is altered after recurrent ankle lateral ligament sprains.. The ankle evertor/invertor muscles torque ratios were determined in the different range parts of angular positions by the muscle isokinetic movements.. It is important to determine the movement range part where the evertor muscle weakness after the ankle lateral ligament sprains is more expressed and a repeated trauma of the lateral ligaments is more probable.. Twenty-eight male handball players participated in the tests using an ankle isokinetic inversion-eversion movement investigation dynamometer system. Thirty-three ankle joints were uninjured, but 23 underwent recurrent lateral ligament sprains.. The ankle evertor/invertor muscles torque ratio for the sprained ankles was significantly lower in comparison with the uninjured joints in inversion positions at 50 degrees and 60 degrees of the range of movements in all applied velocities, except the slowest movement (30 degrees /s).. The recurrent ankle lateral ligament sprains reduced the evertor/invertor muscles torque ratio in the inversion positions of the range of movements and therefore the evertor muscle weakness was more expressed in the beginning of the eversion movement.

Topics: Adolescent; Adult; Ankle Injuries; Athletic Injuries; Humans; Ligaments, Articular; Male; Muscle, Skeletal; Sprains and Strains; Torque

Factorial quasi-experimental design.. To quantify the effect of different levels of isokinetic concentric and eccentric knee extensor torques on the anterior tibial translation in subjects with anterior cruciate ligament (ACL) deficiency. Electromyogram (EMG) activity of 4 leg muscles was recorded in order to detect any co-activation of extensors and flexors.. The rehabilitation after an ACL injury is of importance for the functional outcome of the patient. In order to construct a rehabilitation program after that injury, it is important to understand the in vivo relationships between muscle force and tibial translation.. Twelve patients with unilateral ACL injury and 11 uninjured volunteers performed 36 repetitions of a quadriceps contraction at different isokinetic concentric and eccentric torque levels, on a KinCom machine (60 degrees x s(-1)), with simultaneous recordings of tibial translation (CA-4000) and EMG activity from quadriceps and hamstrings muscles. Tibial translations and EMG levels were normalized to the maximum of each subject.. The individual anterior tibial translation increased with increased quadriceps torque in a similar manner in both quadriceps contraction modes in all legs tested. During concentric mode, translation was similar in all groups, but during eccentric mode, the mean translation was 38% larger in the ACL injured knees. No quadriceps-hamstrings co-activation occurred in any test or group.. An ACL deficient knee can limit the translation within a normal space during concentric muscle activity but not during eccentric activity. That limitation depends on other mechanisms than hamstrings co-activation.

Topics: Adolescent; Adult; Anterior Cruciate Ligament; Anterior Cruciate Ligament Injuries; Athletic Injuries; Biomechanical Phenomena; Female; Humans; Knee Joint; Male; Muscle, Skeletal; Physical Therapy Modalities; Tibia; Torque

The objective of this cohort study was to determine the level of off-season sport specific activity, peak isometric adductor torque, and hip abduction flexibility that are predictive of groin or abdominal strain injury in the National Hockey League (NHL).. The subjects were 1292 consenting NHL players. Estimated relative risks of injury are reported using the following exposures: 1) level of sport specific training in the off-season, 2) peak isometric adductor torque, 3) total hip abduction flexibility, 4) previous injury, 5) years of NHL experience, and 6) skate blade hollow measurement. Estimates of probability of injury are predicted for various levels of exposures on the basis of logistic regression analysis.. During training camp, players who reported less than 18 sessions sport specific training in the off-season were at greater than three times the risk of injury than those who did not (relative risk (RR); 3.38 95% confidence interval (CI), 1.45-7.92). Players who reported previous history of this injury were at more than two times the risk of injury than those who did not (RR, 2.88; 95% CI, 1.33-6.26). Veterans were at greater than five times the risk of injury than rookies (RR, 5.69; 95% CI, 2.05-15.85). Peak isometric adductor torque, total abduction flexibility, and skate blade hollow measurement were not predictive of injury. There is evidence of a dose-response gradient as predicted probability of injury decreases with increasing levels of sport specific training. In the regular season, sport specific training was not as strong a risk factor (RR, 2.32; 95% CI, 1.0-5.39).. Low levels of off-season sport specific training and previous injury are clearly risks for groin injury at an elite level of hockey. Future research is required to investigate prevention strategies for this injury in hockey.

Topics: Abdominal Injuries; Adult; Athletic Injuries; Biomechanical Phenomena; Cohort Studies; Groin; Hip Joint; Hockey; Humans; Incidence; Male; Muscle, Skeletal; Physical Endurance; Risk Factors; Torque

Knee flexor strength recovery following anterior cruciate ligament reconstruction with the doubled semitendinosus and gracilis tendons was assessed for up to 12 months post-surgery. Twelve patients were followed up, four at 3 months, five at 6 months and three at 12 months post-surgery. Knee flexor moment was recorded using the Biodex System-3 isokinetic dynamometer. Three sets of five repetitions of reciprocal eccentric/ concentric knee flexion contractions were carried out with each set at 1.05, 2.09 or 3.14 rad x s(-1). T-tests were used to test for significant differences between and within groups. The uninjured leg produced greater average peak moments than the injured leg; significant differences (p < 0.05) were seen between the legs at 1.05 rad x s(-1) for the 3-month group concentrically, and all three groups eccentrically. There was no significant difference (p > 0.05) between groups for the percentage deficit between legs. On average, a 23% deficit in average peak moment was still evident at 12 months both eccentrically and concentrically at 1.05 rad x s(-1). Taken as a whole this evidence suggests that there is a deficit in knee flexor strength up to at least 12 months post-surgery following doubled semitendinosus and gracilis tendon graft reconstruction even after a full rehabilitation protocol.

Topics: Adult; Anterior Cruciate Ligament; Anterior Cruciate Ligament Injuries; Athletic Injuries; Humans; Knee Joint; Male; Movement; Muscle, Skeletal; Tendons; Torque

The object was to study the relationships between calf muscle size and strength in 85 patients an average of 3.1 years after repair of achilles tendon rupture. The isokinetic calf muscle strength results were excellent or good for 73% of the patients, whereas calf muscle size was normal in only 30%. The average plantar flexion peak torque per unit muscle cross-sectional area was higher on the injured side than on the uninjured side. The average calf muscle cross-sectional area deficit was 15+/-9% (p<0.001) of that on the unaffected side, while the average plantar flexion peak torque deficit was speed-dependent, being 9+/-18%, 10+/-18 and 2+/-13% of that on the unaffected side at 30, 90, and 240 degrees/sec (p<0.001). The correlation between cross-sectional area and peak torque varied in the range 0.52-0.61 at 30, 90 and 240 degrees/sec (p<0.001).

Topics: Achilles Tendon; Adult; Anatomy, Cross-Sectional; Athletic Injuries; Chi-Square Distribution; Exercise Therapy; Female; Follow-Up Studies; Foot; Humans; Immobilization; Isometric Contraction; Leg; Male; Middle Aged; Muscle Contraction; Muscle, Skeletal; Rupture; Tomography, X-Ray Computed; Torque; Weight-Bearing

Suprascapular nerve entrapment with isolated paralysis of the infraspinatus muscle is uncommon. However, this pathology has been reported in volleyball players. Despite a lack of scientific evidence, excessive strain on the nerve is often cited as a possible cause of this syndrome. Previous research has shown a close association between shoulder range of motion and strain on the suprascapular nerve. No clinical studies have so far been designed to examine the association between excessive shoulder mobility and the presence of this pathology.. To study the possible association between the range of motion of the shoulder joint and the presence of suprascapular neuropathy by clinically examining the Belgian male volleyball team with respect to several parameters.. An electromyographic investigation, a clinical shoulder examination, shoulder range of motion measurements, and an isokinetic concentric peak torque shoulder internal/external rotation strength test were performed in 16 professional players.. The electrodiagnostic study showed a severe suprascapular neuropathy in four players which affected only the infraspinatus muscle. In each of these four players, suprascapular nerve entrapment was present on the dominant side. Except for the hypotrophy of the infraspinatus muscle, no significant differences between the affected and non-affected players were observed on clinical examination. Significant differences between the affected and non-affected players were found for range of motion measurements of external rotation, horizontal flexion and forward flexion, and for flexion of the shoulder girdle (protraction); all were found to be higher in the affected players than the non-affected players.. This study suggests an association between increased range of motion of the shoulder joint and the presence of isolated paralysis of the infraspinatus muscle in volleyball players. However, the small number of patients in this study prevents definite conclusions from being drawn.

Topics: Adult; Athletic Injuries; Chi-Square Distribution; Electromyography; Humans; Male; Muscle, Skeletal; Muscular Atrophy; Nerve Compression Syndromes; Neural Conduction; Range of Motion, Articular; Scapula; Shoulder; Shoulder Injuries; Shoulder Joint; Statistics, Nonparametric; Torque

In an ongoing prospective study of 14 recreational athletes (12 males and 2 females, mean age 44.2 +/- 7.1 years) with unilateral chronic Achilles tendinosis, we investigated the effect of treatment with heavy-loaded eccentric calf-muscle training. Pain during activity (recorded on a VAS scale) and isokinetic concentric and eccentric calf-muscle strength (peak torque at 90 degrees /second and 225 degrees /second) on the injured and noninjured side were evaluated. In this group of patients, we examined areal bone mineral density (BMD) of the calcaneus after 9 months (range 6-14 months) of training. BMD of the injured side (subjected to heavy-loaded eccentric training) was compared with BMD of the noninjured side. Before onset of heavy-loaded eccentric training, all patients had Achilles tendon pain which prohibited running activity, and significantly lower concentric and eccentric plantar flexion peak torque on the injured compared with the noninjured side. The training program consisted of 12 weeks of daily, heavy-loaded, eccentric calf-muscle training; thereafter the training was continued for 2-3 days/week. The clinical results were excellent-all 14 patients were back at their preinjury level with full running activity at the 3 month follow-up. The concentric and eccentric plantar flexion peak torque had increased significantly and did not significantly differ from the noninjured side at the 3 and 9 month follow-up. There were no significant side-to-side differences in BMD of the calcaneus. There was no significant relationship between BMD of the calcaneus and calf-muscle strength. As a comparison group, we used 10 recreational athletes (5 males and 5 females) mean age 40.9 years (range 26-55 years), who were selected for surgical treatment of chronic Achilles tendinosis localized at the 2-6 cm level. Their duration of symptoms and severity of disease were the same as in the experimental group. There were no significant side-to-side differences in BMD of the calcaneus preoperatively, but 12 months postoperatively BMD of the calcaneus was 16.4% lower at the injured side compared with the noninjured side. Heavy-loaded eccentric calf-muscle training resulted in a fast recovery in all patients, equaled the side-to-side differences in muscle strength, and was not associated with side-to-side differences in BMD of the calcaneus. In this group of middle-aged recreational athletes, BMD of the calcaneus was not related to calf-muscle strength.

Topics: Achilles Tendon; Adult; Athletic Injuries; Bone Density; Calcaneus; Chronic Disease; Cumulative Trauma Disorders; Exercise Therapy; Female; Humans; Leg; Male; Middle Aged; Muscle, Skeletal; Prospective Studies; Tendinopathy; Tendon Injuries; Torque; Treatment Outcome; Weight-Bearing

Peak torque expresses a point output which may, but does not always, correlate well with full range output measures such as work or power, particularly in a rehabilitating muscle. This study evaluates isokinetic performance variables, particularly (a) flexor to extensor work and power output ratios of upper and lower extremities and (b) overall upper to lower extremity work and power ratios, in intercollegiate athletes. The purpose was to ascertain how speeds of 30 and 180 degrees/s influence agonist to antagonist ratios for torque, work, and power and to determine the effects of these speeds on upper to lower limb flexor (F), extensor (E), and combined (F + E) ratios, as a guide to rehabilitation protocols and outcomes after injury.. Twenty seven athletic men without upper or lower extremity clinical histories were tested isokinetically at slow and moderately fast speeds likely to be encountered in early stages of rehabilitation after injury. Seated knee extensor and flexor outputs, particularly work and power, were investigated, as were full range elbow extensor and flexor outputs. The subjects were morphologically similar in linearity and muscularity (coefficient of variation 4.17%) so that standardisation of isokinetic outputs to body mass effectively normalised for strength differences due to body size. Peak torque (N.m/kg), total work (J/kg), and average power (W/kg) for elbow and knee flexions and extensions were measured on a Cybex 6000 isokinetic dynamometer. With respect to the raw data, the four test conditions (F at 30 degrees/s; E at 30 degrees/s; F at 180 degrees/s; E at 180 degrees/s) were analysed by one way analysis of variance. Reciprocal (agonist to antagonist) F to E ratios of the upper and lower extremities were calculated, as were upper to lower extremity flexor, extensor, and combined (F + E) ratios. Speed related differences between the derived ratios were analysed by Student's t tests (related samples).. At the speeds tested all torque responses exhibited velocity related decrements at rates that kept flexor to extensor ratios and upper to lower extremity ratios constant (p > 0.05) for work and power. All upper extremity relative torque, work, and power flexion responses were equal to extension responses (p > 0.05) regardless of speed. Conversely, all lower extremity relative measures of torque, work, and power of flexors were significantly lower than extensor responses. In the case of both upper and lower extremities, work and power F to E ratios were unaffected by speed. Moreover, increasing speed from 30 to 180 degrees/s had no effect on upper to lower extremity work and power ratios, whether for flexion, extension, or flexion and extension combined.. Peak torque responses may not adequately reflect tension development through an extensive range of motion. Total work produced and mean power generated, on the other hand, are highly relevant measures of performance, and these, expressed as F to E ratios, are unaffected by speeds of 30 and 180 degrees/s, whether for upper or lower extremities or for upper to lower extremities. In this sample, regardless of speed, the upper extremity produced 55% of the work and 39% of the power of the lower extremity, when flexor and extensor outputs were combined. Injured athletes are, in the early stages of function restoration, often not able to exert tension at fast speeds. An understanding of upper to lower extremity muscular work and power ratios has important implications for muscle strengthening after injury. Knowledge of normal upper to lower extremity work and power output ratios at slow to moderately fast isokinetic speeds is particularly useful in cases of bilateral upper (or lower) extremity rehabilitation, when the performance of a contralateral limb cannot be used as a yardstick.

Topics: Adult; Analysis of Variance; Arm; Athletic Injuries; Body Constitution; Elbow Joint; Ergometry; Humans; Knee Joint; Leg; Male; Muscle Contraction; Muscle, Skeletal; Psychomotor Performance; Sports; Time Factors; Torque; Treatment Outcome; Work

Thirty-eight athletes with unilateral patellar tendinopathy (17 with a tendinopathy of the main body of the tendon, and 21 with an insertional tendinopathy) underwent ultrasound-guided multiple percutaneous longitudinal tenotomy under local anaesthetic infiltration after failure of conservative management. Thirty-four patients were reviewed at least 24 months after the operation. Sixteen patients were rated excellent, nine good, eight fair, and five poor. Nine of the 13 patients with a fair or poor result had an insertional tendinopathy, and eight of them underwent a formal exploration of the patellar tendon. Before the operation, there were some areas of altered echogenicity at and around the site of involvement. These were still visible 6 wk after surgery in 70% of the patients. At the latest follow-up, in the patients with an excellent or good result, the tendon was generally isoechogenic but slightly thicker (P = 0.06) than the normal contralateral. In the patients with a fair or poor result, the tendon was significantly thicker than the contralateral (P = 0.03), and showed some areas of mixed echogenicity. In the patients in whom the procedure was successful, the thicker operated tendon did not interfere with physical training. Bilateral isokinetic peak torque (Nm), average work (Joules), and average power (Watts) were tested at 90 degrees x s(-1). Immediately before the operation, there was no significant difference in peak torque, but total work and average power were significantly lower in the limb to be operated (0.01 < P < 0.05). By the end of the study, although peak torque was, on average, within 7% of the unoperated limb, total work and average power were still significantly lower than in the unoperated limb (0.01 < P < 0.04). Percutaneous longitudinal internal tenotomy is simple, can be performed on an outpatient basis, requires minimal follow-up care, does not hinder further surgery should it be unsuccessful, and, in our experience, has produced no significant complications. In our hands, it has become the first line operative intervention in the treatment of chronic patellar tendinopathy after failure of conservative management. However, patients should be advised that, if they suffer from an tendinopathy at the attachment of the patellar tendon at the lower pole of the patella, a formal surgical exploration with stripping of the paratenon is preferable.

Topics: Adolescent; Adult; Ambulatory Surgical Procedures; Anesthesia, Local; Athletic Injuries; Chronic Disease; Ergometry; Female; Follow-Up Studies; Humans; Isometric Contraction; Male; Middle Aged; Minimally Invasive Surgical Procedures; Musculoskeletal Diseases; Patellar Ligament; Prospective Studies; Range of Motion, Articular; Torque; Treatment Outcome; Ultrasonography, Interventional; Weight-Bearing

Operative treatment for ruptures of the long biceps tendon still is discussed controversially. In the present literature surgical repair is advised for sporting and high demand patients due to favourable functional results and low loss of strength. Until now only few objective and reproducible results were published. In the present literature the keyhole-technique is recommended due to favourable bio-mechanical conditions. To evaluate postoperative strength 19 patients were investigated after an average follow-up of 6.5 years, by clinical examination and isokinetic measurement. Compared with the non-operated shoulder isokinetic determination of isometric maximal peak torque and strength during concentric stress for elbow-flexion, shoulder-abduction and shoulder-flexion yield to almost identical results for the operated shoulder. According to the criteria of the Constant-Score all patients achieved very good and good results. Refixation to the short head can be advised for treatment of ruptures of the long biceps tendon due to the certain technique with a low complication rate and very good functional outcome.

Topics: Adult; Aged; Athletic Injuries; Elbow Joint; Exercise; Female; Follow-Up Studies; Humans; Male; Middle Aged; Muscle, Skeletal; Range of Motion, Articular; Rupture; Shoulder Injuries; Shoulder Joint; Tendon Injuries; Time Factors; Torque

An epidemiological study suggested that the injury mechanism of 'handball goalie's elbow' may be hyperextension. The pathomechanics of hyperextension combined with supination was studied in ten macroscopically normal, male, cadaveric elbow joint specimens. The age of the donors was 28.8 years (range 18-45 years). Extension loading of the elbow was performed in an experimental three-dimensional (3D)-kinematic loading apparatus. The degree of extension increased by 16.7 degrees +/- 8.7 degrees after loading. Hyperextension loads induced significant joint laxity in joint flexion (< 50 degrees) during forced valgus, external and internal rotation, respectively, but not during forced varus. The hyperextension trauma produced three lesions: (1) anterior capsule rupture, (2) avulsion of the proximal insertion of both the medial and the lateral collateral ligaments, and (3) occasional single rupture of the lateral collateral ligament. The lesions indicate that combined hyperextension and supination represent a possible mechanism leading to 'handball goalie's elbow'.

Topics: Adolescent; Adult; Athletic Injuries; Biomechanical Phenomena; Cadaver; Collateral Ligaments; Elbow Injuries; Elbow Joint; Humans; Male; Middle Aged; Range of Motion, Articular; Torque

Inhibition of the quadriceps muscles was assessed in 13 elite male volleyball players using the interpolated twitch technique. This technique involves applying an electrical stimulus to the voluntarily contracted quadriceps muscles to estimate the number of motor units not fully activated during the contraction. Knee extensor moments and muscle inhibition were measured during isometric contractions at knee angles of 30 degrees and 60 degrees from full extension. A medical history of knee joint injury and pain experienced in the knee during testing were assessed. Previous knee joint injury did not affect the knee extensor moments, but produced a difference in muscle inhibition: muscle inhibition in legs with previous injuries was significantly lower than muscle inhibition in legs with no previous injury. Moderate pain in the knee during testing did not affect muscle inhibition, but was associated with reduced knee extensor moments. We consider that the loss in knee extensor moments associated with pain might be caused by atrophy of the quadriceps muscles as a consequence of the disrupted training routine. The lower muscle inhibition in volleyball players with previous injury suggested that the intense rehabilitation programme that these athletes undergo after knee injury improves muscle activation. As a result, athletes with previous knee joint injuries were able to produce the same knee extensor moments as athletes with no previous injury, probably because of their ability to recruit the available motor units more completely. This recruitment may compensate for the possible loss in muscle mass encountered during the period of injury and detraining.

Topics: Adult; Athletic Injuries; Chi-Square Distribution; Electric Stimulation; Humans; Isometric Contraction; Knee Injuries; Male; Motor Neurons; Muscle Contraction; Muscle, Skeletal; Pain Measurement; Sports; Torque

Accelerated rehabilitation for anterior cruciate ligament (ACL) injury and reconstruction surgery is designed to return injured people to athletic activities in approximately 6 months. The small amount of empirical data on this population suggests, however, that the torque at the knee joint may not return until 22 months after surgery during walking and even longer during running. Although the rehabilitation has ended and individuals have returned to preinjury activities, gait mechanics appear to be abnormal at the end of accelerated programs. The purpose of this study was to compare lower extremity joint kinematics, kinetics, and energetics between individuals having undergone ACL reconstruction and accelerated rehabilitation and healthy individuals.. Eight ACL-injured and 22 healthy subjects were tested. Injured subjects were tested 3 wk and 6 months (the end of rehabilitation) after surgery. Ground reaction force and kinematic data were combined with inverse dynamics to predict sagittal plane joint torques and powers from which angular impulse and work were derived.. The difference in all kinematic variables between the two tests for the ACL group averaged 38% (all P < 0.05). The kinematics were not different between the ACL group after rehabilitation and healthy subjects. Angular impulses and work averaged 100% difference for all joints (all P < 0.05) between tests for the ACL group. After rehabilitation, the differences between injured and healthy groups in angular impulse and work at both the hip and knee remained large and averaged 52% (all P < 0.05).. Results indicated that after reconstruction surgery and accelerated rehabilitation for ACL injury, humans walk with normal kinematic patterns but continue to use altered joint torque and power patterns.

Topics: Adult; Analysis of Variance; Anterior Cruciate Ligament; Anterior Cruciate Ligament Injuries; Athletic Injuries; Biomechanical Phenomena; Ergometry; Female; Forecasting; Gait; Hip Joint; Humans; Knee Injuries; Knee Joint; Male; Muscle Contraction; Physical Therapy Modalities; Range of Motion, Articular; Running; Time Factors; Torque; Walking; Weight-Bearing

The purpose of the present study was to investigate the isokinetic muscle strength 6 months after reconstruction of the anterior cruciate ligament (ACL). In order to recommend full-load come-back in sport, sufficient muscle strength may be important. Ninety female elite team handball players (mean 24.1 years) were postoperatively tested with Biodex. The operated limb was compared with the contralateral limb: 82.2% had a hamstring strength of a minimum of 49.6 Nm, corresponding to at least 90% of the non-operated limb, while only 12.2% fulfilled the recommended strength of 117.7 Nm for quadriceps femoris. Patients over 26 years showed significantly lower muscle strength in the operated limb than their younger counterparts. Increased focus on quadriceps femoris muscle strength during rehabilitation may improve the knee function faster after ACL reconstruction.

Topics: Acceleration; Adult; Age Factors; Analysis of Variance; Anterior Cruciate Ligament; Anterior Cruciate Ligament Injuries; Athletic Injuries; Female; Humans; Knee Injuries; Knee Joint; Muscle Contraction; Muscle, Skeletal; Physical Therapy Modalities; Range of Motion, Articular; Retrospective Studies; Rupture; Tendons; Torque

The purpose of this study was to investigate for possible relationships between knee flexion to extension peak torque ratios (F1/Ext(rat)) and low-back injuries in highly active males and females. Forty-eight male (age 25.9 +/- 4.5 years) and 41 female (age 27.3 +/- 2.6 years) competitive rowers, and 20 male (age 26.6 +/- 6.0 years) professional ballet dancers volunteered for the study. Each subject performed a test of lumbar and knee flexor flexibility, isokinetic dynamometry and completed a self-administered questionnaire. Flexibility was assessed by using the sit-and-reach test. Knee flexion to extension peak torques were bilaterally monitored at the angular velocities of 1.04 and 4.19 rad x s(-1). The questionnaire was designed to obtain information regarding the number of days off action (e.g., training, competition, and rehearsals), due to low-back injuries, for the 12-month period prior to testing. Results revealed significant negative correlation coefficients between knee F1/Ext(rat), obtained at 1.04 rad x s(-1), and days off physical activity for oarsmen (r = - 0.69; p < 0.01), oarswomen (r = -0.62; p < 0.01) and male dancers (r = -0.57; p < 0.05). No such correlations were found for either knee F1/ Ext(rat) obtained at the angular velocity of 4.19 rad x s(-1) or between the sit-and-reach test results and low-back injuries. A sub-group of 22 female rowers was re-tested after a 6-8 month period, during which a special hamstring strength training programme was introduced. The main conclusions were: a) the lower the F1/Ext(rat) the greater the degree of low-back injury, b) at least in female rowers, 6-8 months of hamstring strength training can contribute to a reduction of the incidence of low-back injury, and c) isokinetic assessment of quadriceps and hamstrings obtained at lower compared to higher angular velocities is more prognostic of low back injury.

Topics: Adult; Athletic Injuries; Dancing; Female; Humans; Incidence; Knee Joint; Leg; Lumbar Vertebrae; Male; Motor Activity; Muscle Contraction; Muscle, Skeletal; Physical Education and Training; Pliability; Prognosis; Range of Motion, Articular; Sports; Surveys and Questionnaires; Tendons; Torque