vendex and Musculoskeletal-Pain

Both isotonic and isokinetic eccentric muscle contractions are commonly used in muscle research laboratories to induce muscle damage, yet, the muscle damage outcomes between these 2 modes of eccentric contraction have not been compared. The purpose of this study was to compare modes of contraction for differences in muscle damage. 16 men were placed in the isotonic (IT: 110% of maximal isometric torque) or the isokinetic (IK: 120°/s) group, with each group performing 200 eccentric muscle actions of the knee extensors. Isometric peak torque, perceived soreness and CK activity were measured immediately pre and post exercise, and 48-h post exercise. Mean total work (~1700 J) and peak torque per set (~265 Nm) decreased over the 200 repetitions (p<0.01), and was not different between groups. Damage markers changed 48-h post exercise (p<0.05): peak isometric torque (-13%), creatine kinase activity (+200%) and self-perceived muscular soreness (+4 unit change). Significant group×time interactions (p<0.01) indicated that peak isometric torque was 22% lower, and creatine kinase and self-perceived muscular soreness were 330% and 3 unit difference higher in the IT as compared to the IK groups, 48-h post exercise. When equating for total work, skeletal muscle damage markers are higher during IT vs. IK modes. This reflects differences inherent in contraction type and suggests that this should be taken into account during physical rehabilitation.

Topics: Adult; Biomarkers; Creatine Kinase; Exercise; Humans; Isotonic Contraction; Knee; Linear Models; Male; Muscle Contraction; Muscle Strength Dynamometer; Muscle, Skeletal; Musculoskeletal Pain; Pain Measurement; Torque

Two common models to investigate the effect of interventions on muscle damage include using two groups in which one group receives an intervention while the other acts as control, and using contralateral limbs of one group. The latter model is based on the assumption that changes in markers of muscle damage are similar between limbs, but this has not been examined systematically.. This study compared changes in muscle damage markers between dominant and non-dominant arms following maximal eccentric exercise of the elbow flexors.. Eighteen men performed 60 maximal eccentric elbow flexions of each arm separated by 4 weeks with the order of testing between arms randomised. Maximal voluntary isometric torque, range of motion, upper arm circumference, plasma creatine kinase (CK) activity and muscle soreness before and for 7 days following exercise were compared between arms using two-way repeated measures ANOVA.. No significant differences between arms were evident for any of the markers, but significant (P<0.05) differences between first and second bouts were evident for changes in strength, circumference and CK with smaller changes following the second bout. A poor correlation was found for the magnitude of changes in the markers between dominant and non-dominant arms, suggesting that responses to eccentric exercise were not necessarily the same between arms.. These results show that the order affected the responses of dominant and non-dominant arms to the eccentric exercise; however, the contralateral limb design appears to be usable if bout order is counterbalanced and randomised among participants.

Topics: Adult; Arm; Biomarkers; Creatine Kinase; Elbow; Elbow Joint; Humans; Male; Muscle Contraction; Muscle, Skeletal; Musculoskeletal Pain; Resistance Training; Torque

To examine the immediate effects of experimentally induced anterior knee pain (AKP) on involuntary and voluntary quadriceps strength and activation.. Crossover 3 × 3 randomized controlled laboratory study with repeated measures.. Human Performance Research Center, Brigham Young University.. Thirteen neurologically sound volunteers (age, 21.9 ± 3.2 years).. Subjects underwent 3 different conditions (pain, sham, and control). To induce AKP and sham condition, 5% sodium chloride and 0.9% sodium chloride (total volume of 1.0 mL for each condition), respectively, were injected into the infrapatellar fat pad on the dominant leg. No injection was performed for the control condition.. The vastus medialis peak Hoffmann reflex normalized by the peak motor response (H:M ratio) was used to measure involuntary quadriceps activation. Quadriceps central activation ratio (CAR) using maximal isometric knee extension torque (N·m) was calculated to assess voluntary quadriceps activation. The visual analog scale was used to measure pain perception.. Our pain model increased perceived pain immediately after the 5% hypertonic saline injection and pain lasted for 12 minutes on average (F40,743 = 16.85, P < 0.001). During the pain condition, subjects showed a 12% decrease in H:M ratio (F2,59 = 8.64, P < 0.001), a 34% decrease in maximal isometric knee extension torque (F2,59 = 5.89, P < 0.01), and a 5% decrease in CAR (F2,59 = 3.83, P = 0.03).. Our data showed that joint pain may be an independent factor to alter function of the muscles surrounding the painful joint. Both involuntary and voluntary inhibitory pathways may play a role in an immediate reduction of muscle activation.

Topics: Adult; Cross-Over Studies; Electromyography; Humans; Knee Joint; Musculoskeletal Pain; Pain Measurement; Pain Perception; Quadriceps Muscle; Range of Motion, Articular; Reflex; Saline Solution, Hypertonic; Torque; Young Adult

This study investigated the time wise protective effect conferred by two maximal voluntary isometric contractions (2MVCs) at 20° elbow flexion on muscle damage induced by 30 maximal isokinetic (60° s(-1)) eccentric contractions of the elbow flexors (MaxECC). Sixty-five young untrained men were randomly assigned to a control group that did not perform 2MVCs, or one of four experimental groups (n = 13 per group) who performed 2MVCs either immediately (0d), 2 (2d), 4 (4d) or 7 days (7d) before MaxECC. Changes in maximal isokinetic (60° s(-1)) concentric torque (MVC-CON), optimum angle (OA), range of motion, upper arm circumference, muscle soreness, plasma creatine kinase activity and myoglobin concentration, and ultrasound echo-intensity following MaxECC were compared among the groups by a two-way repeated measures ANOVA. No significant changes in any variables were evident following 2MVCs. The 2d and 4d groups showed 16-62 % smaller (P < 0.05) changes in all variables following MaxECC than the control, 0d and 7d groups. The 2d group showed 14-34 % smaller (P < 0.05) changes in all variables except for OA compared with the 4d group. The changes in the variables were similar among the control, 0d and 7d groups. These results show that 2MVCs that were performed between 2 and 4 days before MaxECC attenuated the magnitude of muscle damage, but no such effect was evident if the 2MVCs were performed immediately or 7 days before MaxECC. It is concluded that the protective effect conferred by 2MVCs is relatively short-lived, and there is a window for the effect to be conferred.

Topics: Creatine Kinase; Elbow; Exercise; Humans; Isometric Contraction; Male; Movement; Muscle Strength; Muscle, Skeletal; Musculoskeletal Pain; Myoglobin; Range of Motion, Articular; Torque; Ultrasonography; Young Adult

This study investigated whether maximal voluntary isometric contractions (MVC-ISO) would attenuate the magnitude of eccentric exercise-induced muscle damage. Young untrained men were placed into one of the two experimental groups or one control group (n = 13 per group). Subjects in the experimental groups performed either two or 10 MVC-ISO of the elbow flexors at a long muscle length (20° flexion) 2 days prior to 30 maximal isokinetic eccentric contractions of the elbow flexors. Subjects in the control group performed the eccentric contractions without MVC-ISO. No significant changes in maximal voluntary concentric contraction peak torque, peak torque angle, range of motion, upper arm circumference, plasma creatine kinase (CK) activity and myoglobin concentration, muscle soreness, and ultrasound echo intensity were evident after MVC-ISO. Changes in the variables following eccentric contractions were smaller (P < 0.05) for the 2 MVC-ISO group (e.g., peak torque loss at 5 days after exercise, 23% ± 3%; peak CK activity, 1964 ± 452 IU·L(-1); peak muscle soreness, 46 ± 4 mm) or the 10 MVC-ISO group (13% ± 3%, 877 ± 198 IU·L(-1), 30 ± 4 mm) compared with the control (34% ± 4%, 6192 ± 1747 IU·L(-1), 66 ± 5 mm). The 10 MVC-ISO group showed smaller (P < 0.05) changes in all variables following eccentric contractions compared with the 2 MVC-ISO group. Therefore, two MVC-ISO conferred potent protective effects against muscle damage, whereas greater protective effect was induced by 10 MVC-ISO, which can be used as a strategy to minimize muscle damage.

Topics: Arm; Creatine Kinase; Cumulative Trauma Disorders; Elbow Joint; Exercise; Humans; Isometric Contraction; Male; Muscle, Skeletal; Musculoskeletal Pain; Myoglobin; Resistance Training; Torque; Ultrasonography; Young Adult

Runners often experience delayed onset muscle soreness (DOMS), especially of the knee extensors, following prolonged running. Sagittal knee joint biomechanics are altered in the presence of knee extensor DOMS but it is unclear how muscle soreness affects lower limb biomechanics in other planes of motion. The purpose of this study was to assess the effects of knee extensor DOMS on three-dimensional (3D) lower limb biomechanics during running. Thirty-three healthy men (25.8 ± 6.8 years; 84.1 ± 9.2 kg; 1.77 ± 0.07 m) completed an isolated eccentric knee extensor damaging protocol to elicit DOMS. Biomechanics of over-ground running at a set speed of 3.35 m s

Topics: Adult; Ankle; Ankle Joint; Biomechanical Phenomena; Exercise; Gait; Humans; Knee; Knee Joint; Male; Muscle, Skeletal; Musculoskeletal Pain; Myalgia; Range of Motion, Articular; Resistance Training; Running; Torque; Young Adult

To determine the extent of asymmetrical deficits in knee extensor and flexor muscles, and to examine whether asymmetrical muscle deficits are associated with mobility limitations in persons with late-stage knee osteoarthritis (OA).. Cross-sectional.. Research laboratory.. A clinical sample (N=56; age range, 50-75y) of eligible persons with late-stage knee OA awaiting knee replacement.. Not applicable.. Knee extensor and flexor power and torque assessed isokinetically; thigh muscle cross-sectional area (CSA) assessed by computed tomography; mobility limitation assessed by walking speed and stair ascension time; and pain assessed with the Western Ontario and McMaster Universities Osteoarthritis Index questionnaire.. The asymmetrical deficits in knee extensor and flexor power and torque were between 18% and 29% (P<.001). Regarding the thigh muscle CSA, the asymmetrical deficit was 4% (P<.001). Larger asymmetrical knee extensor power deficits and weaker knee extensor and flexor power on the contralateral side were associated with slower stair ascension times. Moreover, weaker knee extensor and flexor power on the ipsilateral side were associated with slower stair ascension times. Greater knee pain in the OA joint was independently associated with slower stair ascending time in both models.. The knee extensor and flexor muscle power of both the ipsilateral and contralateral sides and the pain in the OA knee were independently associated with stair ascension times. These results highlight the importance of assessing muscle power on both sides and knee pain in the prevention of mobility limitations in patients with knee OA.

Topics: Aged; Cross-Sectional Studies; Female; Gait; Humans; Male; Middle Aged; Mobility Limitation; Muscle Strength; Musculoskeletal Pain; Organ Size; Osteoarthritis, Knee; Quadriceps Muscle; Radiography; Time Factors; Torque

Occupational tasks involve awkward upper limb postures, especially movement of forearm with repetitive combined gripping and torqueing exertions, which may lead to development of WMSDs. From the literature survey it was observed that there was a lack of studies focussed on the combined effect of torque and grip exertions on forearm discomfort.. The present study was to investigate the effects of grip force, stroke rotation and frequency of exertions on discomfort and Electromyography (EMG) activities of the forearm muscles in a repetitive torqueing task.. Twenty-seven male participants volunteered in this study. The participants performed repetitive exertions for a 5 minutes duration for each combination of the different levels of stroke rotation, grip force and frequency of exertions. Three levels of stroke rotation, three levels of grip force and three levels of frequency of exertion were chosen as independent variables. Therefore a 3 × 3 customized factorial design was used for the experiment for each level of grip force. Hence, the study was divided into three groups on the basis of grip force (50N, 70N and 90N).. The ANOVA showed that stroke rotation and frequency of exertion were significant on discomfort. Further Students Newmann test (SNK) revealed that discomfort was increased with increasing stroke rotation and frequency of exertion. The multivariate analysis of variances (MANOVA) performed on EMG data instead of ANOVA because EMG activities of five muscles simultaneously were recorded. The Results found that extensor muscles were more fatigued in torqueing with gripping task.. It was found that stroke rotation for the torqueing tasks must be kept below 45°. It was concluded that it is important to control stroke rotation to improve performance of repetitive torqueing activity.

Topics: Elbow Joint; Electromyography; Forearm; Hand Strength; Humans; Isometric Contraction; Male; Middle Aged; Muscle Fatigue; Muscle, Skeletal; Musculoskeletal Pain; Pain Measurement; Posture; Range of Motion, Articular; Rotation; Task Performance and Analysis; Torque

This study aimed to investigate the neuromuscular control of the knee during stair descent among female adolescents with patellofemoral pain (PFP) and to report its association with self-reported clinical status assessed by the Knee Injury and Osteoarthritis Outcome Score (KOOS).. Fifty-seven previously untreated female adolescents diagnosed with PFP ages 15-19 yr were recruited from schools. The control group consisted of 29 age-matched healthy female adolescents. Bipolar surface electrodes were placed on vastus medialis and vastus lateralis, and an electronic knee goniometer was placed at the knee to collect knee flexion/extension kinematics. The participants walked down a stairway consisting of 24 steps at their normal pace. Sample entropy was used to quantify the complexity of the time series from surface electromyography and kinematics during the stance phase. Self-reported clinical status was assessed by the KOOS and the maximal quadriceps torque measured using strap-mounted handheld dynamometry.. Female adolescents with PFP were characterized by altered neuromuscular knee control during stair descent, lower maximal quadriceps torque, and poorer KOOS scores across all five domains. Furthermore, a positive association was found between the complexity of surface electromyography from vastus lateralis and self-reported pain determined by KOOSpain, indicating larger impairments in neuromuscular knee control among those with the highest pain levels.. The current findings show that female adolescents with PFP are characterized by altered neuromuscular control of the knee during stair descent and lower maximal quadriceps torque. These results suggest that rehabilitation is needed and should focus on restoring neuromuscular control and muscle strength.

Topics: Adolescent; Adult; Biomechanical Phenomena; Case-Control Studies; Cross-Sectional Studies; Electromyography; Female; Femur; Gait; Humans; Knee Joint; Musculoskeletal Pain; Patella; Quadriceps Muscle; Range of Motion, Articular; Surveys and Questionnaires; Torque; Walking

The aim of this study was to monitor the changes in indirect markers of muscle damage during 3 weeks (9 training sessions) of stretch-shortening (drop jump) exercise with constant load alternated with steep increases in load. Physically active men (n = 9, mean age 19.1 years) performed a program involving a rapid stepwise increase in the number of jumps, drop height, and squat depth, and the addition of weight. Concentric, isometric maximal voluntary contraction (MVC), and stimulated knee extension torque were measured before and 10 minutes after each session. Muscle soreness and plasma creatine kinase activity were assessed after each session. Steep increments in stretch-shortening exercise load in sessions 4 and 7 amplified the postexercise decrease in stimulated muscle torque and slightly increased muscle soreness but had a minimal effect on the recovery of MVC and stimulated torque. Maximal jump height increased by 7.8 ± 6.3% (p < 0.05), 11.4 ± 3.3% (p < 0.05), and 12.8 ± 3.6% (p < 0.05) at 3, 10, and 17 days after the final training session, respectively. Gains in isometric knee extension MVC (7.9 ± 8.2%) and 100-Hz-evoked torque (9.9 ± 9.6%) (both p < 0.05) were observed within 17 days after the end of the training. The magnitude of improvement was greater after this protocol than that induced by a continuous constant progression loading pattern with small gradual load increments in each training session. These findings suggest that plyometric training using infrequent but steep increases in loading intensity and volume may be beneficial to athletic performance.

Topics: Adult; Analysis of Variance; Creatine Kinase; Humans; Isometric Contraction; Knee; Male; Muscle Fatigue; Muscle Strength; Muscle, Skeletal; Musculoskeletal Pain; Plyometric Exercise; Resistance Training; Torque; Young Adult