vendex and Myalgia

The aim of this review was to (1) characterize the time-course of markers of exercise-induced muscle damage (EIMD) based on the level of maximal voluntary contraction torque loss at 24-48h post-exercise (MVCloss24-48h), (2) identify factors (e.g., exercise and population characteristics) affecting the level of MVCloss24-48h, and (3) evaluate the appropriateness of EIMD markers as indicators of MVCloss24-48h.. Magnitude of change of each EIMD markers was normalized using the standardized mean differences method to compare the results from different studies. Time-course of EIMD markers were characterized according to three levels of MVCloss24-48h based on a clustering analysis of the 141 studies included. Association between MVCloss24-48h levels and participant´s characteristics or exercise type/modalities were assessed. Meta-regressions were performed to investigate the associations between MVCloss24-48h and EIMD markers changes at <6h, 24h, 48h, 72h and >96h after exercise.. Time-course of EIMD markers recovery differs between levels of MVCloss24-48h. Training status and exercise type/modality were associated with MVCloss24-48h level (p<0.05). MVCloss24-48h was correlated to changes in myoglobin concentration (<6h), jump height (24h) and range of motion (48h) (p<0.001).. As the exercise could differently affect markers as function of the EIMD severity (i.e., MVCloss24-48h levels), different markers should be used as function of the timing of measurement. Mb concentration should be used during the first hours after the exercise (<6h), whereas jump height (24h) and range of motion (48h) could be used as surrogate for maximal voluntary contraction later. Moreover, training status and exercise type/modality could influence the magnitude of MVCloss24-48h.

Topics: Biomarkers; Exercise; Humans; Lower Extremity; Muscle Contraction; Muscle, Skeletal; Myalgia; Torque

Morawetz, D, Blank, C, Koller, A, Arvandi, M, Siebert, U, and Schobersberger, W. Sex-related differences after a single bout of maximal eccentric exercise in response to acute effects: a systematic review and meta-analysis. J Strength Cond Res 34(9): 2697-2707, 2020-The most prominent effects after unaccustomed eccentric exercise are muscle damage, muscle soreness, strength loss, and higher concentrations of muscle proteins in the plasma. The aim of this systematic review is to evaluate sex-related differences in these acute effects. A systematic literature search in MEDLINE following the PRISMA guidelines was performed. Inclusion criteria were the difference in absolute outcomes between sexes in eccentric muscle strength, strength loss after eccentric exercise, blood concentrations of creatine kinase (CK), and delayed onset muscle soreness (DOMS). Results for maximal eccentric torque and CK data were pooled using a random-effect meta-analysis. A meta-regression was conducted to explain heterogeneity. Based on the 23 included trials, men showed significantly higher absolute eccentric strength. No sex-related differences were detected when normalizing strength for body mass, cross-sectional area of the muscle, or fat-free mass. Women displayed a tendency toward greater relative strength loss immediately after exercise. The absolute CK concentrations of men were significantly higher after exercise-induced muscle damage. No significant difference was found between sexes in DOMS. Untrained men and women display similar responses in all measures of relative muscle strength and DOMS. Apart from the enzymatic activity after exercise and the levels of absolute eccentric torque, there is no evidence for sex-related differences immediately after eccentric exercise. Therefore, eccentric training might have the same impact on men and women. One potential sex difference with practical relevance would be the possible difference in fatigue pattern immediately after eccentric exercise.

Topics: Adult; Creatine Kinase; Exercise; Female; Humans; Male; Muscle Strength; Muscle, Skeletal; Myalgia; Sex Factors; Torque

Neuromuscular electrical stimulation (NMES) is widely utilized to enhance muscle performance. However, the optimal NMES waveform with respect to treatment effect has not been established.. To investigate the effects of kilohertz-frequency alternating current (KFAC) and low-frequency pulsed current (PC) on quadriceps evoked torque and self-reported discomfort.. PubMed, The Cochrane Library, EMBASE, MEDLINE, Physiotherapy Evidence Database (PEDro), SinoMed, ISI Web of Knowledge, and CINAHL were searched for randomized controlled trials (RCTs) and quasi-randomized controlled trials (QRCTs).. Two reviewers independently selected potential studies according to the inclusion criteria, extracted data, and assessed methodological quality.. Studies were eligible if they compared KFAC versus PC interventions. Studies that included outcome measures for percentage of maximal isometric voluntary contraction (%MIVC) torque and self-reported discomfort level were eligible for evaluation. Seven studies involving 127 individuals were included. The methodological quality of eligible trials was moderate, with a mean of 5 on the 10-point PEDro scale. Overall, PC was no better than KFAC in terms of evoked torque and there was no difference in self-reported discomfort level.. KFAC and PC have similar effects on quadriceps evoked torque and self-reported discomfort level in healthy individuals. The small number and overall methodological quality of currently available studies included in this meta-analysis indicate that new RCTs are needed to better determine optimal NMES treatment parameters.

Topics: Biomechanical Phenomena; Electric Stimulation Therapy; Healthy Volunteers; Humans; Isometric Contraction; Muscle Strength; Myalgia; Pain Threshold; Quadriceps Muscle; Torque

Exercise-induced muscle damage (EIMD) is prevalent especially in sports and rehabilitation. It causes loss in skeletal muscle function and soreness. As there are no firm preventive strategies, we aimed to evaluate the preventive efficacy of nonthermal 448-kHz capacitive resistive monopolar radiofrequency (CRMRF) therapy after eccentric bouts of EIMD response in knee flexors.. Twenty-nine healthy males (age: 25.2 [4.6] y) were randomized in control group (CG; n = 15) and experimental group (EG; n = 14) where EG followed 5 daily 448-kHz CRMRF therapies. All assessments were performed at baseline and post EIMD (EIMD + 1, EIMD + 2, EIMD + 5, and EIMD + 9 d). We measured tensiomyography of biceps femoris and semitendinosus to calculate contraction time, the maximal displacement and the radial velocity of contraction, unilateral isometric knee flexors maximal voluntary contraction torque, and rate of torque development in first 100 milliseconds.. Maximal voluntary contraction torque and rate of torque development in first 100 milliseconds decreased more in CG than in EG and recovered only in EG. Biceps femoris contraction time increased only in CG (without recovery), whereas in semitendinosus contraction time increased in EG (only at EIMD + 1) and in CG (without recovery). In both muscles, tensiomyographic maximal displacement decreased in EG (in EIMD + 1 and EIMD + 2) and in CG (without recovery). Furthermore, in both muscles, radial velocity of contraction decreased in EG (from EIMD + 1 until EIMD + 5) and in CG (without recovery).. The study shows beneficial effect of CRMRF therapy after inducing EIMD in skeletal muscle strength and contractile parameters in knee flexors.

Topics: Adult; Humans; Isometric Contraction; Male; Muscle Contraction; Muscle Strength; Muscle, Skeletal; Myalgia; Pain; Torque

Unaccustomed exercise causes muscle damage resulting in loss of muscle function, which may be attributable to exercise-induced increases in skeletal muscle reactive oxygen species. This study examined the effect of mitochondria-targeted antioxidant supplementation on recovery of muscle function following exercise. Thirty-two untrained men received MitoQ (20 mg/day) or a placebo for 14 days before performing  300 maximal eccentric contractions of the knee extensor muscles of 1 leg. Muscle function was assessed using isokinetic dynamometry before, immediately after, and 24, 48, 72, and 168 hours after exercise. Muscle soreness was assessed using a visual analogue scale 24, 48, 72, and 168 hours after exercise. Blood samples were collected before, immediately after, and 2, 24, 48, 72, and 168 hours after exercise and urine samples were collected before and during the 48 hours after exercise. The reduction in maximal voluntary isometric contraction force and peak concentric torque following exercise was unaffected by MitoQ while recovery of peak eccentric torque was delayed in the MitoQ group. Exercise-induced increases in urine F

Topics: Antioxidants; Creatine Kinase; Dietary Supplements; F2-Isoprostanes; Humans; Isometric Contraction; Male; Mitochondria; Muscle Contraction; Muscle, Skeletal; Muscular Diseases; Myalgia; Torque

This study aimed to investigate the acute effect of capacitive and resistive electric transfer (CRet) intervention on eccentrically damaged muscle. A total of 28 healthy and sedentary male volunteers were randomly allocated to either CRet intervention or control groups. The participants performed a bout of eccentric exercise of the knee extensors with the dominant leg and received 30 min of CRet intervention of the quadriceps 48 h after the exercise. The dependent variables for the analysis were knee flexion range of motion (ROM), muscle soreness and maximum voluntary isometric (MVC-ISO), and concentric contraction (MVC-CON) torque of the knee extensors. These were measured prior to exercise (baseline) and before and after CRet intervention (48 h after the exercise). The results showed that knee flexion ROM, muscle strength (MVC-ISO and MVC-CON), and muscle soreness significantly improved after CRet intervention. CRet intervention may improve muscle soreness and loss of muscle function in an eccentrically damaged muscle.

Topics: Exercise; Humans; Male; Muscle Strength; Muscle, Skeletal; Myalgia; Quadriceps Muscle; Torque

An animal study demonstrated that 6-(Methylsulfinyl)hexyl isothiocyanate (6-MSITC), a major bioactive compound in Japanese pungent spice wasabi, has an action of inhibiting the activation of calpain-1 (a protease). Increases in calpain activity can cause continual strength loss after eccentric exercise. It remains to be determined in humans whether 6-MSITC intake would modulate calpain and/or muscle damage responses after eccentric exercise. We performed a randomized, double-blind, crossover design study wherein eight healthy young males were randomly assigned to ingest 9 mg/day of 6-MSITC or placebo from 1 day before exercise to 4 days after exercise (30 maximal isokinetic eccentric contractions of the elbow flexors using an isokinetic dynamometer). Calpain-1 concentration, inflammatory and muscle damage markers (creatine kinase activity, urinary titin concentration, muscle strength, range of motion, muscle soreness and transverse relaxation time) were assessed. Plasma calpain-1 concentration after eccentric exercise was similar between the placebo- and 6-MSITC-treated conditions. All muscle damage and inflammatory markers were not affected by 6-MSITC relative to those in the placebo-treated condition. Our results suggest that 6-MSITC has no effect on plasma calpain-1 concentration and muscle damage and inflammatory markers measured after eccentric exercise.

Topics: Calpain; Cross-Over Studies; Eating; Humans; Isometric Contraction; Isothiocyanates; Male; Muscle Contraction; Muscle, Skeletal; Myalgia; Range of Motion, Articular; Torque

We examined changes in plasma creatine kinase (CK) activity, hydroxyproline and cell-free DNA (cfDNA) concentrations in relation to changes in maximum voluntary isometric contraction (MVIC) torque and delayed-onset muscle soreness (DOMS) following a session of volume-matched higher- (HI) versus lower-intensity (LI) eccentric cycling exercise.. Healthy young men performed either 5 × 1-min HI at 20% of peak power output (n = 11) or 5 × 4-min LI eccentric cycling at 5% of peak power output (n = 9). Changes in knee extensor MVIC torque, DOMS, plasma CK activity, and hydroxyproline and cfDNA concentrations before, immediately after, and 24-72 h post-exercise were compared between groups.. Plasma CK activity increased post-exercise (141 ± 73.5%) and MVIC torque decreased from immediately (13.3 ± 7.8%) to 48 h (6.7 ± 13.5%) post-exercise (P < 0.05), without significant differences between groups. DOMS was greater after HI (peak: 4.5 ± 3.0 on a 10-point scale) than LI (1.2 ± 1.0). Hydroxyproline concentration increased 40-53% at 24-72 h after both LI and HI (P < 0.05). cfDNA concentration increased immediately after HI only (2.3 ± 0.9-fold, P < 0.001), with a significant difference between groups (P = 0.002). Lack of detectable methylated HOXD4 indicated that the cfDNA was not derived from skeletal muscle. No significant correlations were evident between the magnitude of change in the measures, but the cfDNA increase immediately post-exercise was correlated with the maximal change in heart rate during exercise (r = 0.513, P = 0.025).. Changes in plasma hydroxyproline and cfDNA concentrations were not associated with muscle fiber damage, but the increased hydroxyproline in both groups suggests increased collagen turnover. cfDNA may be a useful metabolic-intensity exercise marker.

Topics: Adult; Cell-Free Nucleic Acids; Creatine Kinase; Exercise Test; Heart Rate; Humans; Hydroxyproline; Isometric Contraction; Male; Myalgia; Torque

We previously showed 8-week of fish oil supplementation attenuated muscle damage. However, the effect of a shorter period of fish oil supplementation is unclear. The present study investigated the effect of fish oil, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), for 4 weeks on muscular damage caused by eccentric contractions (ECCs) of the elbow flexors.. Twenty-two untrained men were recruited in this double-blind, placebo-controlled, parallel design study and the subjects were randomly assigned to the EPA and DHA group (EPA and DHA, n = 11) and placebo group (PL, n = 11). They consumed either EPA 600 mg and DHA 260 mg per day or placebo supplement for 4 weeks prior to exercise. Subjects performed 60 ECCs at 100 % maximal voluntary contraction (MVC) using a dumbbell. Changes in MVC torque, range of motion (ROM), upper arm circumference, muscle soreness, echo intensity, muscle thickness, serum creatine kinase (CK), and interleukin-6 (IL-6) were assessed before exercise; immediately after exercise; and 1, 2, 3, and 5 days after exercise.. ROM was significantly higher in the EPA and DHA group than in the PL group immediately after performing ECCs (p < 0.05). No differences between groups were observed in terms of MVC torque, upper arm circumference, muscle soreness, echo intensity, and thickness. A significant difference was observed in serum CK 3 days after ECCs (p < 0.05).. We concluded that shorter period EPA and DHA supplementation benefits joint flexibility and protection of muscle fiber following ECCs.

Topics: 8,11,14-Eicosatrienoic Acid; Arachidonic Acid; Arm; Creatine Kinase; Dietary Supplements; Docosahexaenoic Acids; Eicosapentaenoic Acid; Elbow Joint; Fatty Acids, Unsaturated; Fish Oils; Humans; Interleukin-6; Isometric Contraction; Male; Myalgia; Placebos; Range of Motion, Articular; Time Factors; Torque; Young Adult

To investigate the effects of a single session of either peristaltic pulse dynamic leg compressions (PPDC) or local heat therapy (HT) after prolonged intermittent shuttle running on skeletal muscle glycogen content, muscle function, and the expression of factors involved in skeletal muscle remodeling.. Twenty-six trained individuals were randomly allocated to either a PPDC (n = 13) or a HT (n = 13) group. After completing a 90-min session of intermittent shuttle running, participants consumed 0.3 g·kg-1 protein plus 1.0 g·kg-1 carbohydrate and received either PPDC or HT for 60 min in one randomly selected leg, while the opposite leg served as control. Muscle biopsies from both legs were obtained before and after exposure to the treatments. Muscle function and soreness were also evaluated before, immediately after, and 24 h after the exercise bout.. The changes in glycogen content were similar (P > 0.05) between the thigh exposed to PPDC and the control thigh ~90 min (Control: 14.9 ± 34.3 vs PPDC: 29.6 ± 34 mmol·kg-1 wet wt) and ~210 min (Control: 45.8 ± 40.7 vs PPDC: 52 ± 25.3 mmol·kg-1 wet wt) after the treatment. There were also no differences in the change in glycogen content between thighs ~90 min (Control: 35.9 ± 26.1 vs HT: 38.7 ± 21.3 mmol·kg-1 wet wt) and ~210 min (Control: 61.4 ± 50.6 vs HT: 63.4 ± 17.5 mmol·kg-1 wet wt) after local HT. The changes in peak torque and fatigue resistance of the knee extensors, muscle soreness, and the mRNA expression and protein abundance of select factors were also similar (P > 0.05) in both thighs, irrespective of the treatment.. A single 1-h session of either PPDC or local HT does not accelerate glycogen resynthesis and the recovery of muscle function after prolonged intermittent shuttle running.

Topics: Adolescent; Adult; Female; Glycogen; Hot Temperature; Humans; Intermittent Pneumatic Compression Devices; Knee; Male; Muscle Fatigue; Muscle Proteins; Muscle Strength; Muscle, Skeletal; Myalgia; RNA, Messenger; Running; Torque; Young Adult

This study aimed at determining the effect of kinesio-taping (KT) on muscle performance and delayed onset muscle soreness (DOMS) after exercise induced muscle damaged. Sixty-six healthy men volunteered to participate (age:18-25 y/o), who performed 200 isokinetic lengthening contractions of the dominant quadriceps. Then subjects were randomized to either control (no treatment), sham (no tape tension), or KT (10% tape tension) groups. Muscle performance was assessed by peak torque and muscular work during maximal isometric and concentric isokinetic contractions. DOMS intensity was assessed using a visual analog scale. Measurements were taken pre-exercise (Pre), 48 h and 96 h post-exercise. Repeated measures ANOVA was used for comparisons within group, and ANCOVA for comparisons among groups. Muscle damage was confirmed in all participants by an increase in CK activity level (p<0.01). Decrease in isometric and isokinetic peak torque was detected at 48 h in the control and sham groups (p<0.01). Muscular work decreased in all groups at 48 h (p<0.01). No differences between groups were detected in muscular performance variables. Increase in DOMS intensity was determined in all groups at 48 h. Comparisons between groups showed lower DOMS intensity in the KT group at 48 h. KT decreased DOMS intensity perception after exercise-induced muscle damage; however, it did not impact muscular performance.

Topics: Adolescent; Adult; Athletic Performance; Athletic Tape; Creatine Kinase; Exercise; Humans; Isometric Contraction; Male; Muscle Contraction; Myalgia; Pain Perception; Quadriceps Muscle; Time Factors; Torque; Young Adult

We examined the effect of curcumin (CUR) ingestion before or after exercise on changes in muscle damage and inflammatory responses after exercise. We conducted two parallel experiments with different CUR ingestion timings using a double-blind crossover. In Exp. 1, ten healthy men ingested 180 mg d

Topics: Adult; Biomarkers; Creatine Kinase; Cross-Over Studies; Curcumin; Dietary Supplements; Double-Blind Method; Eating; Elbow; Exercise; Humans; Inflammation; Interleukin-8; Isometric Contraction; Male; Muscle, Skeletal; Myalgia; Range of Motion, Articular; Torque

Dynamic stretching (DS) is often performed during warm-up to help avoid hamstring muscle injuries, increase joint flexibility, and optimize performance. We examined the effects of DS of the hamstring muscles on passive knee extension range of motion (ROM), passive torque (PT) at the onset of pain (as a measure of stretch tolerance), and passive stiffness of the muscle-tendon unit over an extended period after stretching. Twenty-four healthy subjects participated, with 12 each in the experimental and control groups. Stretching was performed, and measurements were recorded using an isokinetic dynamometer pre-intervention, and at 0, 15, 30, 45, 60, 75, and 90 min post-intervention. DS consisted of ten 30-s sets of 15 repetitions of extension and relaxation of the hamstrings. ROM increased significantly (range, 7%-10%) immediately after DS, and the increase was sustained over 90 min. PT at the onset of pain also increased immediately by 10% but returned to baseline by 30 min. Passive stiffness decreased significantly (range, 7.9%-16.7%) immediately after DS, and the decrease was sustained over 90 min. Post-DS values were normalized to pre-DS values for the respective outcomes in both groups. ROM was significantly higher (range, 7.4%-10%) and passive stiffness was significantly lower (range, 5.4%-14.9%) in the experimental group relative to the control group at all time points. Normalized PT values at the onset of pain were significantly higher in the experimental group at 0-15 min than in the controls, but the differences were smaller at 30-45 min and not significant thereafter. We conclude that DS increases ROM and decreases passive stiffness in a sustained manner, and increases PT at the onset of pain for a shorter period. Overall, our results indicate that when performed prior to exercise, DS is beneficial for the hamstring muscles in terms of increasing flexibility and reducing stiffness.

Topics: Female; Hamstring Muscles; Humans; Knee; Male; Muscle Stretching Exercises; Muscle Tonus; Myalgia; Range of Motion, Articular; Torque; Young Adult

Curcumin is known to have potent anti-inflammatory effects. We have reported that acute curcumin ingestion attenuates eccentric exercise-induced muscle damage. This study aimed to examine the effect of curcumin ingestion timing (before or after exercise) on the changes in muscle damage markers after eccentric exercise. In this randomized, single-blind, parallel design study, 24 healthy young men performed 30 maximal isokinetic (120º/s) eccentric contractions of the elbow flexors using an isokinetic dynamometer. Subjects were randomly assigned to ingest 180 mg/d of oral curcumin either 7 d before (PRE) or 4 d after exercise (POST) or 180 mg/d of oral placebo 4 d after exercise (CON). The maximal voluntary contraction (MVC) torque of the elbow flexors, elbow joint range of motion (ROM), muscle soreness, and serum creatine kinase (CK) activity were measured before, immediately after, and 1-4 d after exercise. Changes in these variables were compared over time. In the POST group, ROM were higher at 3-4 d and muscle soreness was lower at 3 d after exercise compared with the CON group (p<0.05). However, in the PRE group, there were no significant differences compared with the CON group in changes in ROM and muscle soreness. Meanwhile, there were no significant differences among the groups in terms of changes in MVC torque and serum CK activity. Our results suggest that curcumin ingestion after exercise had a more beneficial effect in attenuating muscle soreness.

Topics: Adult; Anti-Inflammatory Agents, Non-Steroidal; Creatine Kinase; Curcumin; Eating; Elbow; Elbow Joint; Exercise; Healthy Volunteers; Humans; Kinetics; Male; Muscle Strength Dynamometer; Muscle Stretching Exercises; Myalgia; Range of Motion, Articular; Single-Blind Method; Sports Nutritional Physiological Phenomena; Time Factors; Torque; Young Adult

This study aimed to investigate the effect of supplementation of fish oil rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on the damage of the biceps brachii after eccentric contractions (ECCs) of the elbow flexors, particularly focusing on muscle stiffness.. Sixteen men were included in this double-blind, placebo-controlled, parallel design study and the participants were randomly assigned to the EPA and DHA supplement group (EPA, n = 8) and placebo group (PL, n = 8). They consumed either EPA 600 mg and DHA 260 mg per day or placebo supplement for 8 weeks prior to exercise. Moreover, they performed six sets of 10 ECCs at 100% maximal voluntary contraction (MVC) using a dumbbell. Changes in MVC torque, range of motion (ROM), upper arm circumference, muscle soreness, muscle echo intensity, and muscle stiffness were assessed before exercise; immediately after exercise; and 1, 2, and 5 days after exercise.. MVC torque and ROM were significantly higher in the EPA group than in the PL group after ECCs (p < 0.05). Muscle soreness, upper arm circumference, and muscle echo intensity were significantly higher in the PL group than in the EPA group after ECCs (p < 0.05). In addition, muscle stiffness at 150° was significantly higher in the PL group than in the EPA group immediately after ECCs (p < 0.05).. The present study showed that EPA and DHA supplementation has a positive role in inhibiting muscle stiffness after ECCs.. This trial (UMIN000028165) was registered on 10th/July/2017.

Topics: Docosahexaenoic Acids; Double-Blind Method; Eicosapentaenoic Acid; Elbow; Fish Oils; Humans; Isometric Contraction; Male; Muscle, Skeletal; Myalgia; Range of Motion, Articular; Torque; Young Adult

Voluntary activation deficit of the quadriceps muscle group is a common symptom in populations with knee joint injury. Musculoskeletal modeling and simulations can improve our understanding of pathological conditions; however, they are mathematically complex which can limit their clinical application. A practical subject-specific modeling framework is introduced to evaluate knee extensor inhibition and muscle force contributions to isometric knee joint torques in healthy adults with and without experimentally induced quadriceps muscle pain.. A randomized cross-over placebo controlled study design was used. Subject-specific maximum knee joint extension torque and quadriceps electromyographic data from 13 uninjured young adults were combined in a modeling framework to determine optimal muscle strength scaling parameters and ideal torque. Strength deficit ratios (experimental torque/ideal torque) and individual muscle contribution to experimental torque was computed before and after intramuscular hypertonic (pain inducing) and isotonic (sham) saline was injected to the vastus medialis.. Decreased experimental knee extension torque (-8%) and vastus medialis electromyography (-26%) amplitude pre- to post- hypertonic injection was observed. Correspondingly, significant decreases in the knee extensor strength deficit ratio (-18%) and percent contribution of vastus medialis to experimental torque (-24%) was observed pre- to post- hypertonic injection. No differences were observed with isotonic injections, confirming the validity of the model.. Our practical method to estimate strength ratios can be easily implemented within a musculoskeletal modeling framework to improve the validity of model estimates. This, in turn, can increase our understanding of the relationship between neuromuscular deficits and functional outcomes in patient populations.

Topics: Adult; Analysis of Variance; Cross-Over Studies; Electromyography; Female; Humans; Knee Injuries; Knee Joint; Male; Muscle Strength; Myalgia; Quadriceps Muscle; Torque; Young Adult

Green, MS, Martin, TD, and Corona, BT. Effect of caffeine supplementation on quadriceps performance after eccentric exercise. J Strength Cond Res 32(10): 2863-2871, 2018-Caffeine use is common among athletes seeking to capitalize on its potential ergogenic effects. Limited research has examined caffeine's effects when used after activities that resulted in exercise-induced muscle damage (EIMD). This study examined the effect of caffeine supplementation on uninjured and injured muscle. Eight men and women (N = 16) who were physically active individuals participated in this study (age: 24.3 ± 4.3 years; height: 173.0 ± 7.0 cm, mass: 75.2 ± 11.5 kg; body fat: 18.2 ± 15.9%). One leg was assessed under uninjured and injured (100 eccentric quadriceps contractions) conditions after caffeine supplementation (6 mg·kg), with the other leg assessed under both conditions after placebo supplementation. Compared with the placebo, caffeine increased peak isokinetic torque by 6.8 ± 2.3 and 9.4 ± 2.5% in uninjured and injured muscle, respectively, but had no effect on maximal voluntary isometric torque or fatigue index in uninjured or injured muscle, with treatments exhibiting similar (p > 0.05) alterations in isometric torque (-11.9 ± 2.2%), fatigue index (-13.9 ± 3.4%), and soreness (+44.0 ± 4.7) after eccentric contractions. The results of this study suggest that caffeine possesses a similar ergogenic effect on isokinetic torque in both uninjured and injured states, but no effect on the production of isometric torque, perception of soreness, or degree of relative fatigue. Athletes should consider the potential caffeine supplementation possesses during recovery from activities that resulted in EIMD.

Topics: Adult; Athletes; Caffeine; Cross-Over Studies; Exercise; Female; Humans; Male; Muscle Fatigue; Muscle Strength; Myalgia; Performance-Enhancing Substances; Quadriceps Muscle; Torque; Young Adult

Effects of passive static stretching intensity on recovery from unaccustomed eccentric exercise of right knee extensors was investigated in 30 recreationally active males randomly allocated into 3 groups: high-intensity (70%-80% maximum perceived stretch), low-intensity (30%-40% maximum perceived stretch), and control. Both stretching groups performed 3 sets of passive static stretching exercises of 60 s each for hamstrings, hip flexors, and quadriceps, over 3 consecutive days, post-unaccustomed eccentric exercise. Muscle function (eccentric and isometric peak torque) and blood biomarkers (creatine kinase and C-reactive protein) were measured before (baseline) and after (24, 48, and 72 h) unaccustomed eccentric exercise. Perceived muscle soreness scores were collected immediately (time 0), and after 24, 48, and 72 h postexercise. Statistical time × condition interactions observed only for eccentric peak torque (p = 0.008). Magnitude-based inference analyses revealed low-intensity stretching had most likely, very likely, or likely beneficial effects on perceived muscle soreness (48-72 h and 0-72 h) and eccentric peak torque (baseline-24 h and baseline-72 h), compared with high-intensity stretching. Compared with control, low-intensity stretching had very likely or likely beneficial effects on perceived muscle soreness (0-24 h and 0-72 h), eccentric peak torque (baseline-48 h and baseline-72 h), and isometric peak torque (baseline-72 h). High-intensity stretching had likely beneficial effects on eccentric peak torque (baseline-48 h), but likely had harmful effects on eccentric peak torque (baseline-24 h) and creatine kinase (baseline-48 h and baseline-72 h), compared with control. Therefore, low-intensity stretching is likely to result in small-to-moderate beneficial effects on perceived muscle soreness and recovery of muscle function post-unaccustomed eccentric exercise, but not markers of muscle damage and inflammation, compared with high-intensity or no stretching.

Topics: Adult; Biomarkers; Biomechanical Phenomena; C-Reactive Protein; Creatine Kinase; England; Hamstring Muscles; Humans; Isometric Contraction; Male; Muscle Strength; Muscle Stretching Exercises; Myalgia; Quadriceps Muscle; Recovery of Function; Time Factors; Torque; Treatment Outcome; Young Adult

Running economy (RE) is impaired following unaccustomed eccentric-biased exercises that induce muscle damage. It is also known that muscle damage is reduced when maximal voluntary isometric contractions (MVIC) are performed at a long muscle length 2-4 days prior to maximal eccentric exercise with the same muscle, a phenomenon that can be described as isometric pre-conditioning (IPC). We tested the hypothesis that IPC could attenuate muscle damage and changes in RE following downhill running. Thirty untrained men were randomly assigned into experimental or control groups and ran downhill on a treadmill (-15%) for 30 min. Participants in the experimental group completed 10 MVIC in a leg press machine two days prior to downhill running, while participants in the control group did not perform IPC. The magnitude of changes in muscle soreness determined 48 h after downhill running was greater for the control group (122 ± 28 mm) than for the experimental group (92 ± 38 mm). Isometric peak torque recovered faster in the experimental group compared with the control group (3 days vs. no full recovery, respectively). No significant effect of IPC was found for countermovement jump height, serum creatine kinase activity or any parameters associated with RE. These results supported the hypothesis that IPC attenuates changes in markers of muscle damage. The hypothesis that IPC attenuates changes in RE was not supported by our data. It appears that the mechanisms involved in changes in markers of muscle damage and parameters associated with RE following downhill running are not completely shared.

Topics: Adult; Creatine Kinase; Exercise; Exercise Test; Exercise Therapy; Humans; Isometric Contraction; Male; Muscle, Skeletal; Myalgia; Running; Torque; Young Adult

This study evaluated the acute effects of two different stretch intensities on muscle damage and extensibility.. Twenty-two physically active women (age 20 ± 1.0 years) were divided into two matched groups and undertook eight sets of 30-s passive hamstring stretching. One group stretched to the point of discomfort (POD) and the other to the point of pain (POP). Hamstring passive torque, sit and reach (S&R), straight leg raise (SLR), and markers of muscle damage were measured before, immediately after stretching and 24 h later.. S&R acutely increased and was still increased at 24 h with median (interquartile range) of 2.0 cm (0.5-3.75 cm) and 2.0 cm (0.25-3.0 cm) for POP and POD (p < 0.05), respectively, with no difference between groups; similar changes were seen with SLR. Passive stiffness fully recovered by 24 h and there was no torque deficit. A small, but significant increase in muscle tenderness occurred at 24 h in both groups and there was a very small increase in thigh circumference in both groups which persisted at 24 h in POP. Plasma CK activity was not raised at 24 h.. Stretching to the point of pain had no acute advantages over stretching to the discomfort point. Both forms of stretching resulted in very mild muscle tenderness but with no evidence of muscle damage. The increased ROM was not associated with changes in passive stiffness of the muscle but most likely resulted from increased tolerance of the discomfort.

Topics: Creatine Kinase; Female; Hamstring Muscles; Humans; Muscle Contraction; Muscle Stretching Exercises; Myalgia; Torque; Young Adult

The goal of this project was to examine the influence of a single night of sleep restriction following heavy exercise on cycling time-trial (TT) performance and skeletal muscle function in the morning. Seven recreational cyclists (age, 24 ± 7 years; peak oxygen consumption, 62 ± 4 mL·kg

Topics: Adolescent; Adult; Athletes; Athletic Performance; Bicycling; Exercise; Exercise Tolerance; Female; High-Intensity Interval Training; Humans; Male; Muscle Strength; Muscle Strength Dynamometer; Muscle, Skeletal; Myalgia; Recreation; Severity of Illness Index; Sleep Deprivation; Torque; Young Adult

An acute bout of eccentric contractions (ECC) cause muscle fiber damage, inflammation, impaired muscle function (MF) and muscle soreness (MS). Individually, protein (PRO) and antioxidant (AO) supplementation may improve some aspects of recovery from ECC, though have yet to be combined. We sought to determine if combined PRO and AO supplementation (PRO + AO) improves MS and MF following damaging ECC over PRO alone.. At baseline MS, TC, MF, macro- and micro-nutrient intakes, and total work during the ECC were not different between groups (. Our results suggest PRO facilitates recovery of muscle function within 24 h following ECC, and addition of AO ameliorates MS more than PRO or CHO alone.

Topics: Antioxidants; Dietary Proteins; Dietary Supplements; Exercise; Humans; Male; Muscle, Skeletal; Myalgia; Single-Blind Method; Torque; Young Adult

This study investigated the effect of supplementation with fish oil rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on the M-wave latency of biceps brachii and muscle damage after a single session of maximal elbow flexor eccentric contractions (ECC).. Twenty-one men were completed the randomized, double-blind, placebo-controlled, and parallel-design study. The subjects were randomly assigned to the fish oil group (. Eight weeks of EPA and DHA supplementation may play a protective role against motor nerve function and may attenuate muscle damage after eccentric contractions.. This trial was registered on July 14th 2015 (https://upload.umin.ac.jp/cgi-open-bin/ctr/index.cgi).

Topics: Arm; Dietary Supplements; Docosahexaenoic Acids; Double-Blind Method; Eicosapentaenoic Acid; Elbow Joint; Fish Oils; Humans; Isometric Contraction; Male; Motor Neurons; Muscle, Skeletal; Myalgia; Range of Motion, Articular; Torque; Young Adult

Ferreira, DV, Ferreira-Júnior, JB, Soares, SRS, Cadore, EL, Izquierdo, M, Brown, LE, and Bottaro, M. Chest press exercises with different stability requirements result in similar muscle damage recovery in resistance trained men. J Strength Cond Res 31(1): 71-79, 2017-This study investigated the time course of 96 hours of muscle recovery after 3 different chest press exercises with different stability requirements in resistance-trained men. Twenty-seven men (23.5 ± 3.8 years) were randomly assigned to one of the 3 groups: (a) Smith machine bench press; (b) barbell bench press; or (c) dumbbell bench press. Participants performed 8 sets of 10 repetition maximum with 2 minutes rest between sets. Muscle thickness, peak torque (PT), and soreness were measured pre, post, 24, 48, 72, and 96 hours after exercise. There were no differences in the time course of PT or muscle thickness values of the pectoralis major (p = 0.98 and p = 0.91, respectively) or elbow extensors (p = 0.07 and p = 0.86, respectively) between groups. Muscle soreness of the pectoralis major was also not different between groups (p > 0.05). However, the Smith machine and barbell groups recovered from triceps brachii muscle soreness by 72 hours after exercise (p > 0.05), whereas the dumbbell group did not present any triceps brachii muscle soreness after exercise (p > 0.05). In conclusion, resistance-trained men experience similar muscle damage recovery after Smith machine, barbell, and dumbbell chest press exercise. However, muscle soreness of the elbow extensors takes a longer time to recover after using a barbell chest press exercise.

Topics: Adult; Arm; Athletes; Humans; Male; Muscle Strength; Muscle, Skeletal; Myalgia; Pectoralis Muscles; Resistance Training; Rest; Torque; Weight Lifting; Young Adult

The purpose of this study was to evaluate vascular occlusion (OCC) and sequential intermittent pneumatic compression (SIPC) as recovery strategies after fatiguing resistance exercise. Twelve strength-trained male participants (age: 24.0 ± 6.3 years, height: 180.4 ± 9.7 cm, and weight: 84.8 ± 9.6 kg) participated in a randomized cross-over study. Participants performed a fatiguing resistance exercise bout consisting of 10 sets with 10 repetitions of back squats at 70% 1 repetition maximum with 3-minute rest between sets. Outcome measures of perceived recovery status, muscle soreness, concentric peak isokinetic torque of the quadriceps, squat jump (SJ) height, and countermovement jump (CMJ) height were taken before the fatiguing resistance exercise bout and repeated immediately post, 1 hour, and 24 hours later. Immediately after the postexercise measures, participants undertook 1 of the 3 recovery strategies: OCC, SIPC, and a passive control (CON). Concentric peak isokinetic torque of the quadriceps was decreased significantly immediately post and 1 hour after the fatiguing resistance exercise bout compared with baseline values (p ≤ 0.05). Mean SJ and CMJ jump height decreased significantly immediately post and 1 hour compared with baseline measures, but only the SJ was significantly decreased at 24 hours. There were no significant differences between conditions for any of the postexercise measures (p > 0.05). In conclusion, this study indicates that OCC and SIPC are not effective for attenuating muscle performance loss after a fatiguing resistance exercise bout relative to passive recovery.

Topics: Adult; Cross-Over Studies; Exercise; Fatigue; Humans; Intermittent Pneumatic Compression Devices; Male; Myalgia; Pressure; Quadriceps Muscle; Resistance Training; Torque; Treatment Outcome

It is believed that sport massage after intensive exercise might improve power and perceptual recovery in athletes. However, few studies have been done in this area. This study aimed to examine the effect of massage on the performance of bodybuilders. Thirty experienced male bodybuilders were randomly assigned to either a massage group (n = 15) or a control group (n = 15). Both groups performed five repetition sets at 75-77% of 1RM of knee extensor and flexor muscle groups. The massage group then received a 30-min massage after the exercise protocol while the control group maintained their normal passive recovery. Criteria under investigation included: plasma creatine kinase (CK) level, agility test, vertical jump test, isometric torque test, and perception of soreness. All variables were measured over 6 time periods: baseline, immediately after the DOMS inducing protocol, right after the massage, and 24, 48, and 72 h after the massage. Both groups showed significant (P < .001) decreases in jumping, agility performance, and isometric torque, but significant (P < .001) increases in CK and muscle soreness levels. The massage group in general demonstrated a better recovery rate. As such, a post-exercise massage session can improve the exercise performance and recovery rate in male bodybuilders after intensive exercise.

Topics: Adult; Athletic Performance; Creatine Kinase; Exercise; Humans; Isometric Contraction; Knee; Male; Massage; Movement; Muscle, Skeletal; Myalgia; Perception; Torque; Treatment Outcome; Weight Lifting

Muscle damage and repeated bout effect have been studied after pure eccentric-only exercise. The aim of this study was to evaluate muscle damage and repeated bout effect induced by enhanced eccentric squat exercise using flywheel device.. Thirteen healthy males volunteered for this study. Creatine kinase blood activity (CK), quadriceps isometric peak torque and muscle soreness were used as markers of muscle damage. The dependent parameters were measured at baseline, immediately after and each day up to 96 hours after the exercise session. The intervention consisted of 100 repetitions of enhanced eccentric squat exercise using flywheel device. The same protocol was repeated after 4 weeks.. After the first bout, CK and muscle soreness were significantly greater (P<0.05) than baseline respectively up to 72 and 96 hours. Isometric peak torque was significantly lower (P<0.05) up to 72 hours. After the second bout, CK showed no significant increase (P>0.05), while isometric peak torque and muscle soreness returned to values similar to baseline after respectively 48 and 72 hours. All muscle damage markers were significantly lower after second compared to first bout.. The enhanced eccentric exercise induced symptoms of muscle damage up to 96 hours. However, it provided muscle protection after the second bout, performed four weeks later. Although it was not eccentric-only exercise, the enhancement of eccentric phase provided muscle protection.

Topics: Adult; Creatine Kinase; Exercise; Humans; Male; Muscle Contraction; Muscle, Skeletal; Myalgia; Time Factors; Torque

Musculoskeletal pain is associated with multiple adaptions in movement control. This study aimed to determine whether changes in movement control acquired during acute pain are maintained over days of pain exposure. On day 0, the extensor carpi radialis brevis muscle of healthy participants was injected with nerve growth factor (NGF) to induce persistent movement-evoked pain (n = 13) or isotonic saline as a control (n = 13). On day 2, short-lasting pain was induced by injection of hypertonic saline into extensor carpi radialis brevis muscles of all participants. Three-dimensional force components were recorded during submaximal isometric wrist extensions on day 0, day 4, and before, during, and after saline-induced pain on day 2. Standard deviation (variation of task-related force) and total excursion of center of pressure (variation of force direction) were assessed. Maximal movement-evoked pain was 3.3 ± .4 (0-10 numeric scale) in the NGF-group on day 2 whereas maximum saline-induced pain was 6.8 ± .3 cm (10-cm visual analog scale). The difference in centroid position of force direction relative to day 0 was greater in the NGF group than in the control group (P < .05) on day 2 (before saline-induced pain) and day 4, reflecting changes in tangential force direction used to achieve the task. During saline-induced pain in both groups, tangential and task-related force variation was greater than before and after saline-induced pain (P < .05).. Persistent movement-evoked pain changes force direction from the pain-free direction. Acute pain leads to increased variation in force direction irrespective of persistent movement-evoked pain preceding the acutely painful event. These differences provide novel insight into the search for and consolidation of new motor strategies in the presence of pain.

Topics: Adult; Analysis of Variance; Double-Blind Method; Female; Humans; Isometric Contraction; Male; Movement; Muscle, Skeletal; Myalgia; Nerve Growth Factor; Pain Measurement; Pressure; Torque; Wrist

To examine whether an acute bout of active or dynamic hamstring-stretching exercises would reduce the amount of muscle damage observed after a strenuous eccentric task and to determine whether the stretching protocols elicit similar responses.. A randomized controlled clinical trial.. Thirty-six young male students performed 5 min of jogging as a warm-up and were allocated to 1 of 3 groups: 3 min of static active stretching (SAS), 3 min of dynamic active stretching (DAS), or control (CON). All subjects performed eccentric exercise immediately after stretching. Heart rate, core temperature, maximal voluntary isometric contraction, passive hip flexion, passive hamstring stiffness (PHS), plasma creatine kinase activity, and myoglobin were recorded at prestretching, at poststretching, and every day after the eccentric exercises for 5 d.. After stretching, the change in hip flexion was significantly higher in the SAS (5°) and DAS (10.8°) groups than in the CON (-4.1°) group. The change in PHS was significantly higher in the DAS (5.6%) group than in the CON (-5.7%) and SAS (-6.7%) groups. Furthermore, changes in muscle-damage markers were smaller in the SAS group than in the DAS and CON groups.. Prior active stretching could be useful for attenuating the symptoms of muscle damage after eccentric exercise. SAS is recommended over DAS as a stretching protocol in terms of strength, hamstring range of motion, and damage markers.

Topics: Adult; Area Under Curve; Body Temperature; Creatine Kinase; Exercise; Heart Rate; Hip; Humans; Isometric Contraction; Knee; Male; Muscle Stretching Exercises; Muscle, Skeletal; Myalgia; Myoglobin; Range of Motion, Articular; Thigh; Torque; Young Adult

Eccentric training has been popularized for physical conditioning and prevention/rehabilitation of musculoskeletal disorders, especially due to the expressive responses in terms of muscular strength gain. In view of evidence that low-level laser therapy (LLLT) is able to increase exercise performance and accelerate post-exercise recovery, the aim of this study was to verify the effect of LLLT on hypertrophy and strengthening of knee extensor muscles submitted to eccentric training.. Thirty healthy male subjects were randomized into three groups: Control Group (CG), Training Group (TG) and Training + LLLT Group (TLG). CG received no intervention, while TG and TLG were engaged on an 8-week knee extensor isokinetic eccentric training program. Only subjects from TLG were treated with LLLT (wavelength = 810 nm; power output = 200 mW; total dosage = 240 J) before each training session. Knee extensor muscle thickness and peak torque were assessed through ultrasonography and isokinetic dynamometry, respectively.. CG presented no changes in any variable throughout the study, while eccentric training led to significant increases in muscle thickness and peak torque in TG and TLG. Subjects from TLG reached significantly higher percent changes compared to subjects from TG for sum of muscles' thicknesses (15.4 vs. 9.4%), isometric peak torque (20.5 vs. 13.7%), and eccentric peak torque (32.2 vs. 20.0%).. LLLT applied before eccentric training sessions seems to improve the hypertrophic response and muscular strength gain in healthy subjects.

Topics: Adaptation, Physiological; Adult; Humans; Knee; Low-Level Light Therapy; Male; Muscle Contraction; Muscle, Skeletal; Myalgia; Resistance Training; Torque

To evaluate the effects of a single session of partial-body cryotherapy (PBC) on muscle recovery, 26 young men performed a muscle-damaging protocol that consisted of five sets of 20 drop jumps with 2-min rest intervals between sets. After the exercise, the PBC group (n = 13) was exposed to 3 min of PBC at -110 °C, and the control group (n = 13) was exposed to 3 min at 21 °C. Anterior thigh muscle thickness, isometric peak torque, and muscle soreness of knee extensors were measured pre, post, 24, 48, 72, and 96 h following exercise. Peak torque did not return to baseline in control group (P < 0.05), whereas the PBC group recovered peak torques 96 h post exercise (P > 0.05). Peak torque was also higher after PBC at 72 and 96 h compared with control group (P < 0.05). Muscle thickness increased after 24 h in the control group (P < 0.05) and was significantly higher compared with the PBC group at 24 and 96 h (P < 0.05). Muscle soreness returned to baseline for the PBC group at 72 h compared with 96 h for controls. These results indicate that PBC after strenuous exercise may enhance recovery from muscle damage.

Topics: Adolescent; Cryotherapy; Exercise; Humans; Isometric Contraction; Male; Myalgia; Quadriceps Muscle; Recovery of Function; Time Factors; Torque; Ultrasonography; Young Adult

Compression garments are increasingly popular in long-distance running events where they are used to limit cumulative fatigue and symptoms associated with mild exercise-induced muscle damage (EIMD). However, the effective benefits remain unclear.. This study examined the effect of wearing compression stockings (CS) on EIMD indicators. Compression was applied during or after simulated trail races performed at competition pace in experienced off-road runners.. Eleven highly trained male runners participated in 3 simulated trail races (15.6 km: uphill section 6.6 km, average gradient 13%, and downhill section 9.0 km, average gradient -9%) in a randomized crossover trial. The effect of wearing CS while running or during recovery was tested and compared with a control condition (ie, run and recovery without CS; non- CS). Indicators of muscle function, muscle damage (creatine kinase; CK), inflammation (interleukin-6; IL-6), and perceived muscle soreness were recorded at baseline (1 h before warm-up) and 1, 24, and 48 h after the run.. Perceived muscle soreness was likely to be lower when participants wore CS during trail running compared with the control condition (1 h postrun, 82% chance; 24 h postrun, 80% chance). A likely or possibly beneficial effect of wearing CS during running was also found for isometric peak torque at 1 h postrun (70% chance) and 24 h postrun (60% chance) and throughout the recovery period on countermovement jump, compared with non-CS. Possible, trivial, or unclear differences were observed for CK and IL-6 between all conditions.. Wearing CS during simulated trail races mainly affects perceived leg soreness and muscle function. These benefits are visible very shortly after the start of the recovery period.

Topics: Adult; Biomarkers; Creatine Kinase; Cross-Over Studies; France; Humans; Inflammation Mediators; Interleukin-6; Isometric Contraction; Male; Muscle Fatigue; Muscle Strength; Muscle, Skeletal; Myalgia; Perception; Physical Endurance; Recovery of Function; Running; Severity of Illness Index; Stockings, Compression; Task Performance and Analysis; Time Factors; Torque; Treatment Outcome

Discrepancies exist whether blood flow restriction (BFR) exacerbates exercise-induced muscle damage (EIMD). This study compared low-intensity eccentric contractions of the elbow flexors with and without BFR for changes in indirect markers of muscle damage. Nine untrained young men (18-26 y) performed low-intensity (30% 1RM) eccentric contractions (2-s) of the elbow flexors with one arm assigned to BFR and the other arm without BFR. EIMD markers of maximum voluntary isometric contraction (MVC) torque, range of motion (ROM), upper arm circumference, muscle thickness and muscle soreness were measured before, immediately after, 1, 2, 3, and 4 days after exercise. Electromyography (EMG) amplitude of the biceps brachii and brachioradialis were recorded during exercise. EMG amplitude was not significantly different between arms and did not significantly change from set 1 to set 4 for the biceps brachii but increased for the brachioradialis (p ≤ 0.05, 12.0% to 14.5%) when the conditions were combined. No significant differences in the changes in any variables were found between arms. MVC torque decreased 7% immediately post-exercise (p ≤ 0.05), but no significant changes in ROM, circumference, muscle thickness and muscle soreness were found. These results show that BFR does not affect EIMD by low-intensity eccentric contractions.

Topics: Adult; Biomechanical Phenomena; Cross-Over Studies; Elbow; Electromyography; Humans; Hypertrophy; Isometric Contraction; Male; Muscle Strength Dynamometer; Muscle, Skeletal; Myalgia; Range of Motion, Articular; Regional Blood Flow; Resistance Training; Time Factors; Torque; Tourniquets; Ultrasonography; 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

This study examined eccentric-induced fatigue effects on knee flexor (KF) neuromuscular function and on knee position sense. This design was repeated across two experimental sessions performed 1 week apart to investigate potential repeated bout effects.. Sixteen participants performed two submaximal bouts of KF unilateral eccentric contractions until reaching a 20% decrease in maximal voluntary isometric contraction force. Knee position sense was evaluated with position-matching tasks in seated and prone positions at 40° and 70° of knee flexion so that KF were either antagonistic or agonistic during the positioning movement. The twitch interpolation technique was used to assess KF neuromuscular fatigue. Perceived muscle soreness was also assessed. Measurements were performed before, immediately (POST) and 24 h after (POST24) each eccentric bout.. No repeated bout effect on neuromuscular function and proprioceptive parameters was observed. At POST, central and peripheral factors contributed to the force decrement as shown by significant decreases in voluntary activation level (- 3.8 ± 4.8%, p < 0.01) and potentiated doublet torque at 100 Hz (- 10 ± 15.8%, p < 0.01). At this time point, position-matching errors significantly increased by 1.7 ± 1.9° in seated position at 40° (p < 0.01). At POST24, in presence of muscle soreness (p < 0.05), although KF neuromuscular function had recovered, position-matching errors increased by 0.6 ± 2.6° in prone position at 40° (p < 0.01).. These results provide evidence that eccentric-induced position sense alterations may arise from central and/or peripheral mechanisms depending on the testing position.

Topics: Humans; Isometric Contraction; Knee; Knee Joint; Muscle Contraction; Muscle Fatigue; Muscle, Skeletal; Myalgia; Proprioception; Torque

To understand muscle damage in badminton, changes in neuromuscular function were investigated after simulated badminton singles matches performed by ten state-level male players.. Each participant played eight matches and measurements were taken before, immediately after, and 1 and 24 h after each match. Maximal voluntary isometric contraction (MVC) torque of the knee extensors and flexors, voluntary activation (VA) during MVC and torques generated by doublet (T. Pre-match knee extensor and flexor MVC torques were 278.4 ± 50.8 Nm and 143.0 ± 36.2 Nm, respectively. Knee extensor MVC torque of the dominant leg decreased immediately (12.0 ± 2.9%) and 1 h post-match (16.0 ± 3.2%), but returned to baseline at 24 h post-match. VA (11.4 ± 2.9%), T. Muscle damage induced by singles badminton matches was minimal, but the more the lunges are performed, the greater the neuromuscular fatigue.

Topics: Electromyography; Humans; Isometric Contraction; Knee; Male; Muscle Contraction; Muscle Fatigue; Muscle, Skeletal; Muscles; Myalgia; Racquet Sports; Torque

The present study investigated the effects of a far-infrared radiation (FIR) lamp therapy on changes in muscle damage and proprioception markers after maximal eccentric exercise of the elbow flexors (EF: Study 1) and the knee flexors (KF: Study 2) in comparison to a sham treatment condition. In each study, 24 healthy sedentary women were assigned to a FIR or a sham treatment group (. FIR lamp therapy was effective for recovering muscle strength and proprioception 1–3 days faster to the baseline.FIR lamp therapy was effective for attenuating muscle soreness by 55–60%, and reducing peak plasma CK activity by 45–89%.The effects of the FIR lamp therapy appear to be greater than other therapeutic interventions for eccentric exercise-induced muscle damage that have been investigated previously.

Topics: Exercise; Female; Humans; Isometric Contraction; Muscle, Skeletal; Myalgia; Torque

Individual differences in recovery of muscle strength after eccentric exercise may be influenced by sex and genotype. A candidate genetic polymorphism associated with response during muscle recovery is the

Topics: Female; Humans; Interleukin-6; Isometric Contraction; Male; Matrix Metalloproteinase 3; Muscle Contraction; Muscle Strength; Muscle, Skeletal; Myalgia; Polymorphism, Genetic; Torque

The study aimed to investigate the relationships between the shear modulus of the biceps brachii (BB) and brachialis muscle (BA) and the total of the two (BB+BA), and urinary titin N-terminal fragment (UTF), maximum voluntary isometric contraction (MVC), and other indirect markers. Fifteen healthy men performed five sets of 10 eccentric contractions using a dumbbell corresponding to 50% of MVC at 90° measured at baseline. The elbow joint of the left arm was extended from 90° to 180° (180° = full extension) in 5 s in the exercise, and was returned with support from the examiner to prevent concentric contraction. Shear modulus of BB and BA were measured by ultrasound shear wave elastography, and UTF, MVC, and range of motion of the elbow joint (ROM) were recorded before; immediately after; and 1, 24, 48, 72, 96, and 168 h after the exercise. After calculating the shear modulus of BB and BA, two values were added (BB+BA). The shear modulus peaked at 48 h, UTF peaked at 96 h, MVC and ROM changed largest at immediately, and muscle soreness peaked at 48 h post-exercise. Significant (p < 0.05) relationships were found between changes in BB shear modulus and BA shear modulus (r = 0.874), BB+BA shear modulus (r = 0.977), UTF (r = 0.681), and MVC (r = -0.538). Significant (p < 0.05) relationships were also observed between changes in BA shear modulus and BB+BA shear modulus (r = 0.957), UTF (r = 0.682), MVC (r = -0.522), and ROM (r = -0.600). Moreover, significant (p < 0.05) relationships were observed between changes in BB+BA shear modulus and UTF (r = 0.703), MVC (r = -0.549), and ROM (r = -0.547). These results indicate that shear modulus of each muscle (i.e., BB and BA) provide more precise information about muscle damage than UTF, MVC and ROM.

Topics: Connectin; Elbow; Humans; Male; Muscle, Skeletal; Myalgia; Torque

Unaccustomed eccentric contractions generally result in a long-lasting contractile impairment, referred to as prolonged low-frequency force depression (PLFFD), and delayed-onset muscle soreness (DOMS). We here used repeated drop jumps (DJs) as an eccentric contraction model and studied the effects of increasing the time between DJs from 20 s to 5 min. We hypothesized that both PLFFD and DOMS would be less marked at the longer DJ interval due to the longer time to restore structural elements between DJs.. Young men (n = 12) randomly performed 50 DJs with either 20-s (DJ-20 s) or 5-min (DJ-5 min) rest between DJs. Voluntary, 20 Hz and 100 Hz electrically stimulated isometric knee extension torques and muscle soreness were monitored before and for 7 days after DJs; serum CK activity was measured to assess muscle fibre protein leakage. In additional experiments, changes in mRNA levels were assessed in muscle biopsies collected before and 1 h after exercise.. A marked PLFFD was observed with both protocols and the extent of 20 Hz torque depression was smaller immediately and 1 day after DJ-5 min than after DJ-20 s (p < 0.05), whereas the MVC and 100 Hz torques were similarly decreased with the two protocols. Markedly larger differences between the two protocols were observed for the muscle soreness score, which 1-4 days after exercise was about two times larger with DJ-20 s than with DJ-5 min (p < 0.01).. The larger protective effect of the longer DJ interval against DOMS than against PLFFD indicates that their underlying mechanisms involve different structural elements.

Topics: Adult; Biomarkers; Biopsy, Needle; Creatine Kinase; Electric Stimulation; Humans; Knee; Male; Muscle Contraction; Myalgia; Pain Measurement; Rest; Time Factors; Torque; Young Adult

We investigated whether 20 candidate single nucleotide polymorphisms (SNPs) were associated with in vivo exercise-induced muscle damage (EIMD), and with an in vitro skeletal muscle stem cell wound healing assay. Sixty-five young, untrained Caucasian adults performed 120 maximal eccentric knee-extensions on an isokinetic dynamometer to induce EIMD. Maximal voluntary isometric/isokinetic knee-extensor torque, knee joint range of motion (ROM), muscle soreness, serum creatine kinase activity and interleukin-6 concentration were assessed before, directly after and 48 h after EIMD. Muscle stem cells were cultured from vastus lateralis biopsies from a separate cohort (n = 12), and markers of repair were measured in vitro. Participants were genotyped for all 20 SNPs using real-time PCR. Seven SNPs were associated with the response to EIMD, and these were used to calculate a total genotype score, which enabled participants to be segregated into three polygenic groups: 'preferential' (more 'protective' alleles), 'moderate', and 'non-preferential'. The non-preferential group was consistently weaker than the preferential group (1.93 ± 0.81 vs. 2.73 ± 0.59 N ∙ m/kg; P = 9.51 × 10

Topics: Adult; Exercise; Humans; Muscle, Skeletal; Myalgia; Polymorphism, Single Nucleotide; Quadriceps Muscle; Stem Cells; Torque

Our aim was to determine the demands and consequences of a single session of continuous (CONT) or interval (INT) eccentric cycling. Fourteen healthy males performed 'work-matched' CONT and INT eccentric cycling in a cross over design. Measures of maximal voluntary contraction (MVC), resting twitch force, voluntary activation (VA), muscle soreness and creatine kinase (CK) were taken at baseline, immediately post, and 24, 48 and 72 h post the first exercise bout. The second bout was used to characterise within session demands. Decreases in MVC (INT 19%, CONT 13%), twitch force (INT 31%, CONT 18%), and VA (INT 10%, CONT 6%) were observed immediately post session (

Topics: Bicycling; Cross-Over Studies; Humans; Male; Muscle Contraction; Muscle, Skeletal; Myalgia; Torque

There is a need to investigate the role of muscle architecture on muscle damage responses induced by exercise. The aim of this study was to determine the effect of muscle architecture and muscle length on eccentric exercise-induced muscle damage responses. Eccentric exercise-induced muscle damage was performed randomly to the elbow flexor (EF), knee extensor (KE), and knee flexor (KF) muscle groups with two week intervals in 12 sedentary male subjects. Before and after each eccentric exercise (immediately after, on the 1

Topics: Humans; Knee; Male; Muscle, Skeletal; Myalgia; Range of Motion, Articular; Torque

The purpose of this study was to concomitantly investigate the acute and delayed effects of a submaximal eccentric-induced muscle fatigue on the position sense and the neuromuscular function of the right knee extensor muscles.. Thirteen young and physically active participants performed a unilateral isokinetic eccentric exercise of their right lower limb until a decrease in maximal voluntary isometric contraction (MVIC) of 20% was reached. Neuromuscular (i.e., MVIC, voluntary activation (VA) level, and evoked contractile properties [DB100 and DB10]) and psychophysical evaluations (i.e., bilateral position-matching task, perceived muscle soreness, and perceived fatigue) were performed at four time points: before (PRE), immediately after (POST), 24 (POST24), and 48 (POST48) the exercise.. The acute 20% MVIC reduction (P < 0.001) was associated with both central (i.e., -13% VA decrease, P < 0.01) and peripheral (i.e., -18% and -42% reduction of DB100 and DB10, respectively, P < 0.001) fatigue. In the following days (POST24 and POST48), VA levels had recovered despite the presence of a persisting peripheral fatigue and delayed-onset muscle soreness. Knee position sense, as revealed by position errors, was significantly altered only at POST (P < 0.05) with participants overestimating the length of their knee extensor. Position errors and VA deficits were significantly correlated at POST (r = -0.60, P = 0.03). Position errors returned to nonsignificant control values in the following days.. The acute central fatigue induced by the eccentric exercise contributes to the position sense disturbances. Central fatigue might lead to alterations in the sensory structures responsible for the integration and the processing of position-related sensory inputs.

Topics: Electromyography; Exercise; Femoral Nerve; Humans; Knee; Muscle Fatigue; Myalgia; Perception; Proprioception; Task Performance and Analysis; Torque; Transcutaneous Electric Nerve Stimulation

Eccentric quasi-isometric (EQI) contractions have been proposed as a novel training method for safely exposing the musculotendinous system to a large mechanical load/impulse, with few repetitions. However, understanding of this contraction type is rudimentary. We aimed to compare the acute effects of a single session of isotonic EQIs with isokinetic eccentric (ECC) contractions.. Fifteen well-trained men performed a session of impulse-equated EQI and ECC knee extensions, with each limb randomly allocated to one contraction type. Immediately PRE, POST, 24/48/72 h, and 7 days post-exercise, regional soreness, quadriceps swelling, architecture, and echo intensity were evaluated. Peak concentric and isometric torque, rate of torque development (RTD), and angle-specific impulse were evaluated at each time point.. There were substantial differences in the number of contractions (ECC: 100.8 ± 54; EQI: 3.85 ± 1.1) and peak torque (mean: ECC: 215 ± 54 Nm; EQI: 179 ± 28.5 Nm). Both conditions elicited similar responses in 21/53 evaluated variables. EQIs resulted in greater vastus intermedius swelling (7.1-8.8%, ES = 0.20-0.29), whereas ECC resulted in greater soreness at the distal and middle vastus lateralis and distal rectus femoris (16.5-30.4%, ES = 0.32-0.54) and larger echogenicity increases at the distal rectus femoris and lateral vastus intermedius (11.9-15.1%, ES = 0.26--0.54). Furthermore, ECC led to larger reductions in concentric (8.3-19.7%, ES = 0.45-0.62) and isometric (6.3-32.3%, ES = 0.18-0.70) torque and RTD at medium-long muscle lengths.. A single session of EQIs resulted in less soreness and smaller reductions in peak torque and RTD versus impulse-equated ECC contractions, yet morphological shifts were largely similar. Long-term morphological, architectural, and neuromuscular adaptations to EQI training requires investigation.

Topics: Adult; Humans; Isometric Contraction; Knee; Male; Muscle, Skeletal; Myalgia; Physical Conditioning, Human; Tendons; Torque

Previous evidence from surface electromyograms (EMGs) suggests that exercise-induced muscle damage (EIMD) may manifest unevenly within the muscle. Here we investigated whether these regional changes were indeed associated with EIMD or if they were attributed to spurious factors often affecting EMGs.. Ten healthy male subjects performed 3 × 10 eccentric elbow flexions. Maximal voluntary contraction (MVC), muscle soreness and ultrasound images from biceps brachii distal and proximal regions were measured immediately before (baseline) and during each of the following 4 days after the exercise. Moreover, 64 monopolar surface EMGs were detected while 10 supramaximal pulses were applied to the musculocutaneous nerve. The innervation zone (IZ), the number of electrodes detecting largest M-waves and their centroid longitudinal coordinates were assessed to characterize the spatial distribution of the M-waves amplitude.. The MVC torque decreased (~ 25%; P < 0.001) while the perceived muscle soreness scale increased (~ 4 cm; 0 cm for no soreness and 10 cm for highest imaginable soreness; P < 0.005) across days. The echo intensity of the ultrasound images increased at 48 h (71%), 72 h (95%) and 96 h (112%) for both muscle regions (P < 0.005), while no differences between regions were observed (P = 0.136). The IZ location did not change (P = 0.283). The number of channels detecting the greatest M-waves significantly decreased (up to 10.7%; P < 0.027) and the centroid longitudinal coordinate shifted distally at 24, 48 and 72 h after EIMD (P < 0.041).. EIMD consistently changed supramaximal M-waves that were detected mainly proximally from the biceps brachii, suggesting that EIMD takes place locally within the biceps brachii.

Topics: Adult; Elbow; Evoked Potentials, Motor; Humans; Isometric Contraction; Male; Muscle, Skeletal; Myalgia; Physical Conditioning, Human; Torque

Passive stretching reduces stiffness in the lower limb arteries of the stretched limb. To address this physiological mechanism, we measured the change in shear rate in the posterior tibial artery during a single bout of one-legged passive calf stretching compared with that in the non-stretched leg.. The diameter, mean blood velocity, blood flow, and shear rate in the posterior tibial artery were measured using Doppler ultrasound before (baseline), during, and after a one-legged passive intermittent calf stretching procedure (six repetitions of 30-s static stretch with 10-s relaxation) in nine healthy young men.. In the posterior tibial artery of the stretched leg, the arterial diameter significantly decreased from baseline during the stretching period (baseline vs. stretching period of the 6th set, 0.19 ± 0.01 vs. 0.18 ± 0.01 cm, P < 0.05) without any change in shear rate and mean blood velocity. In contrast, during the relaxation period, the mean blood velocity (baseline vs. relaxation period of the 5th set, 2.98 ± 0.54 vs. 6.25 ± 1.48 cm/s) increased, and consequently, the shear rate (baseline vs. relaxation period of the 5th set, 66.75 ± 15.39 vs. 122.85 ± 29.40 s. The stretching procedure increased the shear rate in the peripheral artery of the stretched leg during the relaxation period. This finding indicates that the local hemodynamic response (possibly through endothelial function), resulting from an increase in shear stress, may contribute to stretching-induced attenuation of local arterial stiffness.

Topics: Humans; Isometric Contraction; Leg; Male; Muscle Stretching Exercises; Muscle, Skeletal; Myalgia; Regional Blood Flow; Torque; Young Adult

High-intensity unaccustomed eccentric contractions result in weakness and power loss because of fatigue and muscle damage. Through the repeated bout effect (RBE), adaptations occur, then damage and weakness are attenuated following a subsequent bout. However, it is unclear whether the RBE protects peak power output. We investigated the influence of the RBE on power production and estimated fatigue- and damage-induced neuromuscular impairments following repeated high-intensity eccentric contractions. Twelve healthy adult males performed 5 sets of 30 maximal eccentric elbow flexions and repeated an identical bout 4 weeks later. Recovery was tracked over 7 days following both bouts. Reduced maximum voluntary isometric contraction torque, and increased serum creatine kinase and self-reported soreness indirectly inferred muscle damage. Peak isotonic power, time-dependent measures - rate of velocity development (RVD) and rate of torque development (RTD) - and several electrophysiological indices of neuromuscular function were assessed. The RBE protected peak power, with a protective index of 66% 24 h after the second eccentric exercise bout. The protection of power also related to preserved RVD (

Topics: Adaptation, Physiological; Adult; Creatine Kinase; Elbow; Humans; Isometric Contraction; Male; Muscle Contraction; Muscle Fatigue; Muscle, Skeletal; Myalgia; Self Report; Torque; Young Adult

The intensity of exercise-induced pain (EIP) reflects the metabolic environment in the exercising muscle, so during endurance exercise, this may inform the intelligent regulation of work rate. Conversely, the acute debilitating effects of EIP on motor unit recruitment could impair the estimation of force produced by the muscle and impair judgement of current exercise intensity. This study investigated whether muscle pain that feels like EIP, administered via intramuscular injection of hypertonic saline, interferes with the ability to accurately reproduce torque in a muscle group relevant to locomotive exercise. On separate days, 14 participants completed an isometric torque reproduction task of the knee extensors. Participants were required to produce torque at 15% and 20% maximal voluntary isometric torque (MVIT), without visual feedback before (baseline), during (pain/no pain), and after (recovery) an injection of 0.9% isotonic saline (Control) or 5.8% hypertonic saline (Experimental) into the vastus lateralis of the right leg. An elevated reported intensity of pain, and a significantly increased variance in mean contraction torque at both 15% (

Topics: Electromyography; Humans; Injections, Intramuscular; Isometric Contraction; Knee; Muscle Contraction; Muscle, Skeletal; Myalgia; Quadriceps Muscle; Reproduction; Torque

This study tested the hypothesis that the magnitude of rectus femoris (RF) damage and the repeated bout effect (RBE) would be greater after knee extensor eccentric exercise performed in a supine (long RF lengths) than a sitting (short RF lengths) position, and the muscle length effects would be more prominent at the proximal than distal RF. Young untrained men were placed to one of the two groups (n = 14 per group). S group performed the knee extensor eccentric exercise in the sitting position for the first bout and the supine position for the second bout, and L group performed the exercise in the supine position for two bouts, with 4 weeks between bouts. Dependent variables included evoked and maximal voluntary isometric contraction (MVC) torque, electromyography (EMG) during MVC, muscle soreness, and shear modulus, which were measured before and 1-3 days after each exercise bout. After the first bout, L group in comparison with S group showed greater (P < .05) changes in hip flexor MVC torque (average of 1-3 days post-exercise: -11.1 ± 9.4% vs -5.0 ± 7.5%), proximal RF EMG (-22.4 ± 16% vs -9.0 ± 21.9%), and proximal RF shear modulus (33.2 ± 22.8% vs 16.9 ± 13.5%). No significant differences between groups were evident for any of other variables after the first bout including knee extensor MVC torque, and for the changes in all variables after the second bout. These results supported the hypothesis that RF damage would be greater for the spine than sitting position especially at the proximal region, but did not support the hypothesis about the RBE.

Topics: Elastic Modulus; Electromyography; Exercise; Humans; Isometric Contraction; Knee; Male; Muscle Strength; Myalgia; Quadriceps Muscle; Sitting Position; Supine Position; Torque; Young Adult

The present study tested the hypothesis that 30 low-intensity (10%) eccentric contractions (10%EC) or two maximal voluntary isometric contractions at a long muscle length (2MVIC) that were performed at two days before maximal eccentric exercise of the elbow flexors consisting of five sets of six maximal eccentric contractions (MaxEC) would reduce increases in biceps brachii distal myotendinous junction displacement (MTJd) over the eccentric contractions during MaxEC. Sedentary young men were randomly placed (n = 12/group) to a control group that performed two bouts of MaxEC (CONT-1st, CONT-2nd) separated by two weeks, or one of two preconditioning groups that performed 10%EC or 2MVIC at 20° elbow flexion at two days prior to MaxEC. All exercises were performed by the non-dominant arm. MTJd of each contraction was assessed by B-mode ultrasound, and its changes over sets were compared among the groups. The average MTJd from the start to the end of six eccentric contractions in the first set was similar among the groups (6.4 ± 0.7 mm). The MTJd increased from the first to fifth set, but the increase was smaller (P < .05) for the 10%EC (13 ± 6%) and 2MVIC (16 ± 9%) groups, and CONT-2nd (3 ± 6%) when compared with CONT-1st (60 ± 12%). Both 10%EC and 2MVIC groups showed smaller (P < .05) changes in all muscle damage markers after MaxEC similarly when compared with CONT-1st, but the changes were greater than those after CONT-2nd. These results supported the hypothesis that protective effect was associated with less MTJd changes, suggesting that this is associated with the mechanisms underpinning the preconditioning effect on muscle damage.

Topics: Creatine Kinase; Exercise; Healthy Volunteers; Humans; Isometric Contraction; Male; Muscle, Skeletal; Myalgia; Range of Motion, Articular; Tendons; Torque; Young Adult

We tested the hypothesis that the magnitude of changes in indirect muscle damage markers would be greater after maximal elbow flexor eccentric exercise in the supinated (shorter biceps brachii) than neutral wrist (longer) position, and the difference in the magnitude would be associated with greater elongation over contractions for the supinated than neutral position, rather than the initial muscle length. Ten untrained men (21-39 years) performed two bouts of 10 sets of 6 maximal isokinetic eccentric contractions of the elbow flexors in the supinated position for one arm and neutral position for the other arm separated by 2 weeks in a randomized order. Biceps brachii myotendinous junction (MTJ) movements during eccentric contractions were recorded by B-mode ultrasonography, and the displacement from the start to end of each contraction was quantified. Peak torque (supinated: 367.8 ± 112.5 Nm, neutral: 381.5 ± 120.4 Nm) and total work (1816 ± 539 J, 1865 ± 673 J) produced during eccentric contractions were similar between conditions. The average MTJ displacement increased (P < .05) from the 1st set (8.0 ± 2.0 mm) to 10th set (15.8 ± 1.9 mm) for the supinated condition, but no such increase was found in the neutral condition (1st set: 5.1 ± 1.0 mm, 10th set: 5.0 ± 0.8 mm). Changes in indirect muscle damage markers (maximal voluntary isometric contraction torque, range of motion, serum creatine kinase activity, and muscle soreness) after exercise were greater (P < .05) for the supinated than neutral condition. These results suggest that the greater muscle damage marker changes for the supinated than neutral wrist position was associated with the greater muscle lengthening (strain).

Topics: Adult; Analysis of Variance; Biomarkers; Creatine Kinase; Elbow Joint; Humans; Isometric Contraction; Male; Muscle, Skeletal; Myalgia; Pain Measurement; Posture; Random Allocation; Range of Motion, Articular; Sprains and Strains; Supine Position; Tendons; Torque; Ultrasonography; Wrist; Young Adult

The present study uniquely examined the influence of old age and adiposity on maximal concentric and eccentric torque and fatigue of the elbow and knee (KF, KE) flexors and extensors. Forty males were recruited and categorised into young (

Topics: Adiposity; Aged; Aging; Body Mass Index; Hand Strength; Humans; Lower Extremity; Male; Muscle Contraction; Muscle Fatigue; Muscle, Skeletal; Myalgia; Task Performance and Analysis; Torque; Upper Extremity; Young Adult

High-intensity eccentric exercise can lead to muscle damage and weakness. The 'repeated bout effect' (RBE) can attenuate these impairments when performing a subsequent bout. The influence of eccentric exercise-induced muscle damage on low-frequency force production is well-characterized; however, it is unclear how eccentric exercise and the RBE affect torque production across a range of stimulation frequencies (i.e., the torque-frequency relationship). We investigated the influence of an initial (Bout 1) and repeated bout (Bout 2) of eccentric exercise on the elbow flexor torque-frequency relationship. Eleven males completed two bouts of high-intensity eccentric elbow flexions, 4 weeks apart. Torque-frequency relationships were constructed at baseline and 0.5, 24, 48, 72, 96, and 168 h following both bouts via percutaneous stimulation at 1, 6, 10, 20, 30, 40, 50, and 100 Hz. Serum creatine kinase activity, self-reported muscle soreness, and isometric maximum voluntary contraction torque indirectly inferred the presence of muscle damage following Bout 1, and attenuation of muscle damage following Bout 2. Torque amplitude at all stimulation frequencies was impaired 30 min following eccentric exercise, however, torque at lower (1-10 Hz) and higher frequencies (40-100 Hz) recovered within 24 h while torque across the middle frequency range (20-30 Hz) recovered by 48 h. No between-bout differences were detected in absolute or normalized torque at any stimulation frequency, indicating no protective RBE on the elbow flexor torque-frequency relationship.

Topics: Exercise; Humans; Isometric Contraction; Male; Muscle Contraction; Muscle, Skeletal; Myalgia; Torque

Controversy remains about whether exercise-induced muscle damage (EIMD) and the subsequent repeated bout effect (RBE) are caused by the stretching of an activated muscle, or the production of high force at long, but constant, muscle lengths. The aim of this study was to determine the influence of muscle fascicle stretch elicited during different muscle contraction types on the magnitude of EIMD and the RBE.. Fourteen participants performed an initial bout of lower limb exercise of the triceps surae. One leg performed sustained static contractions at a constant long muscle length (ISO), whereas the contralateral leg performed a bout of eccentric heel drop exercise (ECC). Time under tension was matched between the ECC and ISO conditions. Seven days later, both legs performed ECC. Plantar flexor twitch torque, medial gastrocnemius (MG) fascicle length and muscle soreness were assessed before, 2 h and 2 days after each exercise bout. MG fascicle length and triceps surae surface electromyography were examined across the bouts of exercise.. We found that both ECC and ISO conditions elicited EIMD and a RBE. ISO caused less damage 2 h after the initial bout (14% less drop in twitch torque, P = 0.03) and less protection from soreness 2 days after the repeated bout (56% higher soreness, P = 0.01). No differences were found when comparing neuromechanical properties across exercise bouts.. For MG, the action of stretching an active muscle seems to be more important for causing damage than a sustained contraction at a long length.

Topics: Adult; Electric Stimulation; Electromyography; Humans; Leg Injuries; Male; Muscle Contraction; Muscle Stretching Exercises; Muscle, Skeletal; Myalgia; Torque

Eccentric contractions (ECCs) cause muscle damage. In addition, we showed that ECCs induce nerve dysfunction and damage with rats and human.. We aimed to evaluate motor nerve conduction velocity (MCV) for flexor pollicis brevis muscle (FPBM) after ECCs.. Twelve men (years, 19.8 ± 1.7 years; height, 172.4 ± 7.0 cm; weight, 64.0 ± 8.6 kg) performed maximal 100 ECCs on their FPBM of non-dominant hands with torque dynamometer. The dominant hands were control (CON). Maximal voluntary contraction (MVC), range of motion (ROM), DOMS, and MCV were assessed before, immediately post, and 1, 2, and 5 days after ECCs. MCV was calculated as the distance by stimulation divided by the latencies of the waveforms generated. Values were statistically analyzed by two-way ANOVA, and the significance level was set at P < .05.. Decreases in MVC immediately (-32.9%) to 5 days after ECCs were significantly greater (P < .05) than for the CON group. ROM showed a significant decrease immediately (-21.6%) after ECCs compared with before ECCs and CON group (P < .05). DOMS after ECCs increased at 1 and 2 days (5.0 cm) after ECCs compared with before ECCs and CON (P < .05). Also, MCV after ECCs delayed significantly from immediately (-36.4%), 1, 2, and 5 days after ECCs compared with CON (P < .05), while no significant change in M-wave amplitude was observed over time for both ECCs and CON.. The present study showed that ECCs of the FPBM cause a significant delay in MCV of median nerve.

Topics: Adolescent; Humans; Male; Motor Neurons; Muscle Contraction; Muscle Strength Dynamometer; Muscle, Skeletal; Myalgia; Neural Conduction; Range of Motion, Articular; Torque; Young Adult

The purpose of the present study was to examine the effects of high intensity static stretching for 20 seconds on flexibility and strength in the hamstrings. Seventeen healthy participants (13 men and 4 women) underwent static stretching for 20 seconds at three different intensities based on the point of discomfort (POD, 120% POD, and MaxPOD). To examine the change in flexibility and strength, range of motion (ROM), passive torque, muscle-tendon unit stiffness, peak torque of maximum voluntary isokinetic concentric contraction, and knee angle at peak torque were measured. To evaluate a time course of pain, a numerical rating scale (NRS) was described. ROM (percent change; POD = 113.5 ± 10.4%, 120%POD = 127.6 ± 18.8%, MaxPOD = 135.6 ± 18.5%) (p < 0.01) and passive torque (percent change; POD = 124.2 ± 38.9%, 120%POD = 143.4 ± 65.1%, MaxPOD = 171.8 ± 83.6%) (p < 0.01) were increased at all intensities. Muscle-tendon unit stiffness was decreased at 120%POD (percent change; 72.4 ± 36.2, p < 0.01) and MaxPOD (percent change; 56.6 ± 30.0, p < 0.01). Peak torque showed no change at all intensities (percent change; POD = 99.1 ± 14.0%, 120%POD = 95.4 ± 17.4%, MaxPOD = 98.4 ± 20.1%, p > 0.05). There were significant correlations between the intensities and relative change of the ROM (r = 0.57, p < 0.01), passive torque (r = 0.46, p < 0.01), muscle-tendon unit stiffness (r = -0.53, p < 0.01) and knee angle at peak torque (r = 0.50, p < 0.01). NRS increased with the intensity of static stretching (median; POD = 1, 120%POD = 3, Max POD = 8), though the pain disappeared immediately after the stretching (median = 0). In conclusion, static stretching for 20 seconds at high intensity was effective for a decrement in muscle-tendon unit stiffness.

Topics: Hamstring Muscles; Humans; Knee; Male; Muscle Contraction; Muscle Strength; Muscle Stretching Exercises; Muscle, Skeletal; Myalgia; Range of Motion, Articular; Tendons; Torque; Warm-Up Exercise; Young Adult

Increased nociceptive activity and the experience of exercise-induced pain (EIP) may contribute to fatigue during endurance exercise. To investigate this, a pain model that produces pain similar to EIP and decouples its relationship to exercise intensity is required. This study (1) compared the quality of pain caused by a hypertonic saline injection into the vastus lateralis in resting and exercise conditions, and (2) investigated whether this pain contributes to changes in time to task failure.. On separate days, 18 participants completed a time to task failure at 20% maximal voluntary torque (MVT), a resting hypertonic saline intramuscular injection, and in a further three visits a time to task failure at 10% MVT following injection of isotonic saline, hypertonic saline or a control (no injection).. In a subset of eligible participants (n = 12), the hypertonic saline combined with 10% MVT produced a qualitative experience of pain (assessed by the McGill Pain Questionnaire) that felt similar to EIP. 10% MVT with hypertonic saline significantly elevated pain intensity in the first 20% of the time to task failure and caused a significantly (P < 0.05) shorter time to task failure (448 ± 240 s) compared with the isotonic saline (605 ± 285 s) and control (514 ± 197 s) conditions.. These findings demonstrate that hypertonic saline increases the intensity of pain during exercise, which results in a faster occurrence of exercise-induced fatigue. These results provide important evidence supporting pain as a limiting factor in endurance performance.

Topics: Adult; Exercise; Female; Humans; Injections, Intramuscular; Knee; Male; Muscle, Skeletal; Myalgia; Pain Measurement; Quadriceps Muscle; Saline Solution, Hypertonic; Torque; Young Adult

Fatigue can be defined as exercise-induced strength loss. During running, fatigue can be partially explained by repetitive low-intensity eccentric contractions-induced muscle damage (EIMD). Previous studies showed that a bout of downhill running (DR) attenuated subsequent EIMD. Thus, we tested if a 30-min DR bout would attenuate fatigue induced by subsequent 60-min level running (LR). Twenty-seven male college students were randomly allocated to an experimental (EXP) or a control (CON) group. All participants performed LR on a treadmill at 70% of the velocity (vVO

Topics: Adult; Fatigue; Humans; Male; Muscle Contraction; Myalgia; Oxygen Consumption; Running; Time Factors; Torque; Young Adult

To measure changes in fatigue and knee-extensor torque in the 48 h after trained men and women completed a full-body resistance exercise session.. Eight trained women (mean ± SD: age, 25.6 ± 5.9 yr; height, 1.68 ± 0.06 m; mass, 71.0 ± 8.6 kg) and eight trained men (age, 25.5 ± 6.2 yr; height, 1.79 ± 0.05 m; mass, 86.4 ± 9.8 kg) performed a full-body resistance exercise session based on real-world athletic practice. Measurements were performed before and after the exercise session, as well as 1, 24, and 48 h after the session. Fatigue and pain were measured with standardized self-report measures. Maximal isometric contractions with the knee extensors and superimposed femoral nerve stimulation were performed to examine maximal torque, rate of torque development, voluntary activation, and muscle contractility. Two sets of 10 isokinetic contractions (60°·s) with the knee extensors were performed during the protocol with use of near-infrared spectroscopy to assess muscle oxygenation. EMG were recorded from two quadriceps muscles during all isometric and isokinetic contractions.. Fatigue was increased from baseline for both sexes until 48 h after training (P < 0.001). Maximal torque and evoked twitch amplitudes were similarly reduced after exercise for men and women (P < 0.001). Voluntary activation and EMG amplitudes were unchanged after the training session. Muscle oxygenation was 13.3% ± 17.4% (P = 0.005) greater for women during the isokinetic repetitions, and the values were unchanged after the training session.. This is the first study to show similar changes in the fatigue reported by trained men and women in the 48 h after a training session involving full-body resistance exercises. Sex differences in muscle oxygenation during exercise do not influence the reductions in muscle force, activation, or contractility after the training session.

Topics: Adult; Female; Humans; Knee; Male; Muscle Contraction; Muscle Fatigue; Muscle, Skeletal; Myalgia; Oxygen Consumption; Resistance Training; Sex Characteristics; Torque; Young Adult

Page, RM, Marrin, K, Brogden, CM, and Greig, M. Physical response to a simulated period of soccer-specific fixture congestion. J Strength Cond Res 33(4): 1075-1085, 2019-The aim of this study was to assess the physiological, perceptual, and mechanical measures associated with the completion of a simulated period of short-term soccer-specific fixture congestion. Ten male semiprofessional soccer players completed 3 trials of a treadmill-based match simulation, with 48 hours interspersing each trial. A repeated measures general linear model identified significantly (p = 0.02) lower knee flexor peak torque (PT) recorded at 300°·s in the second (141.27 ± 28.51 N·m) and third trials (139.12 ± 26.23 N·m) when compared with the first trial (154.17 ± 35.25 N·m). Similarly, muscle soreness (MS) and PT data recorded at 60°·s were significantly (p ≤ 0.05) different in the third trial (MS = 42 ± 25 a.u; PT60 = 131.10 ± 35.38 N·m) when compared with the first trial (MS = 29 ± 29 a.u; PT60 = 145.61 ± 42.86 N·m). Significant (p = 0.003) differences were also observed for mean electromyography (EMGmean) of bicep femoris between the third trial (T0-15 = 126.36 ± 15.57 μV; T75-90 = 52.18 ± 17.19 μV) and corresponding time points in the first trial (T0-15 = 98.20 ± 23.49 μV; T75-90 = 99.97 ± 39.81 μV). Cumulative increases in perceived exertion, heart rate, oxygen consumption, blood lactate concentrations, EMGmean, and PlayerLoad (PL) were recorded across each trial. Muscle soreness and PT were also significantly different after trial. There were, however, no significant main effects or interactions for the salivary immunoglobulin A and the medial-lateral PL metrics. These data suggest a biomechanical and muscular emphasis with residual fatigue, with implications for injury risk and the development of recovery strategies.

Topics: Adult; Electromyography; Exercise Test; Hamstring Muscles; Heart Rate; Humans; Immunoglobulin A; Knee Joint; Lactic Acid; Male; Muscle Fatigue; Myalgia; Oxygen Consumption; Physical Exertion; Quadriceps Muscle; Saliva; Soccer; Torque; Young Adult

Topics: Adult; Ankle Brachial Index; Bicycling; Exercise Test; Humans; Knee; Male; Muscle Contraction; Muscle, Skeletal; Myalgia; Oxygen Consumption; Pulse Wave Analysis; Torque; Vascular Stiffness; Young Adult

Underfat individuals have been neglected as a malnourished population in terms of redox homeostasis. The aim of the present study was to evaluate the effect of body composition on redox homeostasis at rest and in response to exercise. Underfat, lean and overfat women, classified according to their BMI and body fat percentage, participated in the study and were subjected to an acute session of eccentric exercise. With regard to muscle function and damage, a significant group × time interaction was found for range of motion (

Topics: Biomarkers; Body Fat Distribution; Body Mass Index; Creatine Kinase; Energy Metabolism; Exercise; Female; Homeostasis; Humans; Isometric Contraction; Knee; Muscle, Skeletal; Myalgia; Overweight; Oxidation-Reduction; Range of Motion, Articular; Rest; Thinness; Torque; Young Adult

Muscle structure disorganization is a consequence of intense eccentric contractions, with symptoms that characterize exercise-induced muscle damage (EIMD). To date, few studies have described EIMD parameters at different muscle sites. The aim of the present study was to analyse indirect markers of EIMD at two elbow flexors sites over three days. Eleven healthy untrained men were submitted to a session of three sets of 10 eccentric elbow flexion repetitions on an isokinetic dynamometer. The isometric peak torque (PT), muscle soreness, elbow flexors oedema, (normalized muscle thickness [MT]) and echo-intensity (EI) were measured. There was a significant decrease in PT immediately after (Post) and 10 min, 24 h, 48 h and 72 h after intervention compared to that at baseline (p < 0 .05). MT% increased after 72 h compared with that immediately, 10 min and 24 h after intervention (p < 0.05). No statistical changes were observed in muscle soreness and oedema between the two muscle sites. With respect to EI%, significant differences were observed for the 24 h, 48 h and 72 h measures compared with those of the Post, 10 min and 24 h measures for both muscle sites; at the distal site, EI% was significantly higher than at the proximal site for measures after 24 h (p < 0.05). The presence of differences in EI% 24 h after eccentric training on distal sites of elbow flexors indicates non-uniform EIMD in this region.

Topics: Adult; Edema; Elbow; Humans; Isometric Contraction; Male; Muscle Strength Dynamometer; Muscle, Skeletal; Myalgia; Pain Measurement; Resistance Training; Torque; Ultrasonography; Young Adult

External counterpulsation (ECP), an electrocardiogram-led sequential compression of lower limbs, has been recently proposed for sports recovery, but research is scant. This study examined the effects of an ECP session upon neuromuscular function (vertical jump and torque/velocity characteristics), biochemical responses (creatine kinase, cortisol, testosterone, alpha-amylase and immunoglobulin-A), and muscle soreness (visual analogue scale) following high-intensity exercise. Twenty-one male team sport athletes (age: 21.6±3.4 yrs; height: 182.7±7.3 cm; body mass: 82.7±9.3 kg) recovered from the fatiguing exercise using either ECP or rest. Data collection was conducted at three separate time points: upon arrival (Pre), post-recovery (Post), and 24 h post-recovery (24hPost). Significant main effects for time were observed for increased torque/velocity slope and for decreased isometric extension peak torque (p<0.001). Significant main effects for time were observed for increased creatine kinase, testosterone, alpha-amylase, and muscle soreness (all p<0.001). Significant interaction effects were observed at post-testing following ECP: Cortisol release and the related decline in testosterone/cortisol ratio were attenuated, and immunoglobulin-A was increased following ECP in comparison to the control (all p<0.05). Following high-intensity exercise, ECP has potentially beneficial effects upon biomarkers of recovery, without affecting the neuromuscular function.

Topics: alpha-Amylases; Biomarkers; Counterpulsation; Creatine Kinase; Exercise; Humans; Hydrocortisone; Immunoglobulin A; Male; Muscle Fatigue; Muscle, Skeletal; Myalgia; Saliva; Sports; Testosterone; Torque; Young Adult

The grey level of co-occurrence matrix (GLCM) is a texture analysis approach accounting for spatial distribution of the pixels from an image and can be a promising method for exercise-induced muscle damage (EIMD) studies. We followed up the time changes of two GLCM texture parameters and echo intensity (EI) on ultrasound images after eccentric contractions. Thirteen untrained women performed two sets of ten elbow flexions eccentric contractions. Ultrasound images were acquired at baseline and 24 h, 48 h, 72 h and 96 h after exercise. Two GLCM texture parameters were calculated for the brachialis muscle: contrast (CON) and correlation (COR). Peak torque, EI, muscle thickness (MT) and soreness were measured. The peak torque and soreness decreased immediately after the intervention in comparison with all the measures. MT increased immediately after the intervention remaining for 72 h (P<0·05). Significant increases (P<0·05) were observed for COR (48, 72 and 96 h) and EI only at 72 and 96 h. The increasing COR represents high similarity between grey levels, which could be observed on US images after few days on eccentric training for elbow flexors.

Topics: Elbow; Female; Humans; Image Interpretation, Computer-Assisted; Muscle Contraction; Muscle Strength; Muscle, Skeletal; Myalgia; Predictive Value of Tests; Resistance Training; Time Factors; Torque; Ultrasonography; Young Adult

Eccentric exercise of the elbow flexors (EF) confers protective effect against muscle damage of the same exercise performed by the opposite arm at 1, 7, or 28 d later. This is known as the contralateral repeated bout effect (CL-RBE), but it is not known whether CL-RBE is evident for the knee flexors (KF). The present study tested the hypothesis that KF CL-RBE would be observed at 1, 7, and 28 d after the initial bout.. Young untrained men were assigned to a control or one of three experimental groups (n = 13 per group). The experimental groups performed 60 maximal KF eccentric contractions (60MaxEC) using one leg followed by the same exercise using the opposite leg at 1, 7, or 28 d later. The control group used the nondominant leg to repeat 60MaxEC separated by 14 d. Changes in several indirect muscle damage markers after 60MaxEC were compared between bouts and among the groups by using a mixed-design, two-way ANOVA.. Changes in maximal voluntary isokinetic concentric contraction torque, range of motion, muscle soreness, and plasma creatine kinase activity after the first 60MaxEC were similar among the groups. These changes were smaller after the second than the first 60MaxEC for the control, 1-d, and 7-d groups, and the changes after the second 60MaxEC were smaller for the control than for both the 1- and 7-d groups (P < 0.05). When the KF CL-RBE was compared with the EF CL-RBE of the previous study, the magnitude was not significantly different.. These results showed that CL-RBE was evident for KF in a similar manner to that for EF, but did not last for 28 d, and the CL-RBE was smaller than the ipsilateral RBE.

Topics: Creatine Kinase; Exercise; Humans; Knee Joint; Male; Muscle Contraction; Muscle, Skeletal; Myalgia; Range of Motion, Articular; Torque; Young Adult

The purpose of present study was to examine the association between ACTN3 R577X genotype and functional characteristics of elbow flexors before and after isokinetic eccentric contractions (ECCs). Fifty-two men (age: 20.8±3.8 years, height: 172.5±5.9 cm, body mass: 64.7±6.5 kg, BMI: 21.7±1.7) who had not participated in any regular resistance training for at least 1 year prior to this study were recruited. ECCs consisted of five sets of six maximal voluntary isokinetic (30°/s) ECCs of the elbow flexors with a range of motion (ROM) from 90° flexion to 0° (full extension). Measurements of maximal voluntary isometric contraction (MVC) torque, ROM, and muscle soreness were taken before, immediately after, and 1, 2, 3, and 5 days after ECCs. Genotyping results were analyzed for identifying ACTN3 R577X polymorphism (rs1815739) using TaqMan approach. The genotype frequencies of the ACTN3 R577X polymorphism were RR 26.9% (n=14), RX 50.0% (n=26), and XX 23.1% (n=12). There were no significant differences in MVC torque, ROM, and soreness between three genotype groups of ACTN3 R577X. However, MVC at baseline was greater in RR homozygotes than in X-allele carriers (combined XX and RX; p<0.05). ROM in RR homozygotes at baseline was lower than that of X-allele carriers. Although a significant decrease in ROM was observed in X-allele carriers until 3 days after ECCs, a significant ROM reduction in RR homozygotes was observed only immediately after ECCs. Our data indicated that ACTN3 RR genotype has higher MVC and lower flexibility than X-allele carriers at baseline, but the effect of ACTN3 R577X genotype on these two parameters is limited after ECCs.

Topics: Actinin; Elbow; Genes, X-Linked; Genotype; Humans; Isometric Contraction; Male; Muscle Strength; Myalgia; Polymorphism, Single Nucleotide; Range of Motion, Articular; Resistance Training; Time Factors; Torque; Young Adult

Muscle damage after 30 maximal eccentric contractions of the elbow flexors (30MVEC) is reduced when the same exercise is performed by the opposite arm, and when two maximal voluntary isometric contractions at a long muscle length (2MVIC) are performed prior to 30MVEC by the same arm. This study investigated the hypothesis that 2MVIC would attenuate muscle damage after 30MVEC performed by the opposite arm. Untrained young (20-25 years) men were placed into 1 of 4 experimental groups that performed 2MVIC at 1 (1d), 2 (2d), 4 (4d), or 7 days (7d) before 30MVEC by the opposite arm, or one control group that performed 30MVEC only (n = 13/group). Changes in indirect muscle damage markers after 30MVEC were compared among the groups by mixed-design two-way ANOVA. Maximal voluntary concentric contraction torque, range of motion, plasma creatine kinase activity, and muscle soreness did not change significantly after 2MVIC. Changes in these variables after 30MVEC were smaller (P < .05) for 1d (eg, peak soreness: 45 ± 21 mm) and 2d groups (46 ± 20 mm) than control group (66 ± 18 mm), without significant differences between 1d and 2d groups. No significant differences in the changes were found among 4d, 7d, and control groups, except for soreness showing smaller (P < .05) increases for 4d group (54 ± 19 mm) than 7d (62 ± 17 mm) and control groups. These results supported the hypothesis and showed that muscle damage induced by 30MVEC was reduced by 2MVIC performed 1-2 days prior to 30MVIC by the contralateral arm.

Topics: Adult; Arm; Elbow Joint; Exercise; Humans; Isometric Contraction; Male; Muscle, Skeletal; Myalgia; Range of Motion, Articular; Torque; Young Adult

Adaptations to 6 weeks of supervised hamstring stretching training and its potential impact on symptoms of eccentric exercise-induced muscle damage (EIMD) were studied in 10 young, untrained men with limited hamstrings flexibility. Participants performed unilateral flexibility training (experimental leg; EL) on an isokinetic dynamometer, while the contralateral limb acted as control (CL). Hip range of motion (ROM), passive, isometric, and concentric torques, active optimum angle, and biceps femoris and semitendinosus muscle thickness and ultrasound echo intensity were assessed both before and after the training. Additionally, muscle soreness was assessed before and after an acute eccentric exercise bout in both legs (EL and CL) at post-training only. Hip ROM increased (P < .001) only in EL after the training (EL = 10.6° vs CL = 1.6°), but no changes (P > .05) in other criterion measurements were observed. After a bout of eccentric exercise at the end of the program, isometric and dynamic peak torques and muscle soreness ratings were significantly altered at all time points equally in EL and CL. Also, active optimum angle was reduced immediately, 48 and 72 hours post-exercise, and hip ROM was reduced at 48 and 72 hours equally in EL and CL. Finally, biceps femoris muscle thickness was significantly increased at all time points, and semitendinosus thickness and echo intensity significantly increased at 72 hours, with no significant differences between legs. The stretching training protocol significantly increased hip ROM; however, it did not induce a protective effect on EIMD in men with tight hamstrings.

Topics: Adaptation, Physiological; Adult; Hamstring Muscles; Hip; Humans; Male; Muscle Stretching Exercises; Myalgia; Range of Motion, Articular; Resistance Training; Torque; Young Adult

Changes in muscle fascicle mechanics have been postulated to underpin the repeated bout effect (RBE) observed following exercise-induced muscle damage (EIMD). However, in the medial gastrocnemius (MG), mixed evidence exists on whether fascicle stretch amplitude influences the level of EIMD, thus questioning whether changes in fascicle mechanics underpin the RBE. An alternative hypothesis is that neural adaptations contribute to the RBE in this muscle. The aim of this study was to investigate the neuromechanical adaptations during and after repeated bouts of a highly controlled muscle lengthening exercise that aimed to maximize EIMD in MG. In all, 20 subjects performed two bouts of 500 active lengthening contractions (70% of maximal activation) of the triceps surae, separated by 7 days. Ultrasound constructed fascicle length-torque (L-T) curves of MG, surface electromyography (EMG), maximum torque production, and muscle soreness were assessed before, 2 hours and 2 days after each exercise bout. The drop in maximum torque (4%) and the increase in muscle soreness (24%) following the repeated bout were significantly less than following the initial bout (8% and 59%, respectively), indicating a RBE. However, neither shift in the L-T curve nor changes in EMG parameters were present. Furthermore, muscle properties during the exercise were not related to the EIMD or RBE. Our results show that there are no global changes in gastrocnemius mechanical behavior or neural activation that could explain the observed RBE in this muscle. We suggest that adaptations in the non-contractile elements of the muscle are likely to explain the RBE in the triceps surae.

Topics: Adaptation, Physiological; Adult; Biomechanical Phenomena; Electromyography; Exercise; Female; Humans; Male; Muscle Contraction; Muscle, Skeletal; Myalgia; Torque; Ultrasonography; Young Adult

The magnitude of muscle damage induced by maximal eccentric contractions (MaxEC) of the elbow flexors (EF) is reduced when it is preceded by low-intensity (10% of maximal voluntary isometric contraction strength) eccentric contractions (10%EC) of the same muscle, or by MaxEC of the opposite EF. This study investigated whether 10%EC would reduce the magnitude of muscle damage after MaxEC performed by the opposite arm.. Comparison among 6 groups for changes in indirect markers of muscle damage.. Young (21.0±1.8years) untrained men were assigned to five experimental groups (n=13/group) that performed 30, 10%EC followed by 30 MaxEC of the other arm performed at either 1 (1d), 2 (2d), 7 (1wk), 14 (2wk) or 21days (3wk) later, and one control group that performed 30 MaxEC without 10%EC (n=13). Changes in several indirect markers of muscle damage after MaxEC were compared among the groups by mixed-design two-way ANOVAs.. No significant changes in maximal voluntary concentric contraction torque, plasma creatine kinase activity and muscle soreness were evident after 10%EC. Changes in these variables after MaxEC were smaller (p<0.05) for the 1d, 2d and 1wk groups than control group, without significant differences between the 1d, 2d and 1wk groups. No significance differences in the changes were evident among the 2wk, 3wk and control groups, except for muscle soreness showing smaller (p<0.05) increases for the 2wk and 3wk groups than control group.. These results showed that 10%EC conferred muscle damage protection to the contralateral arm that performed MaxEC.

Topics: Creatine Kinase; Elbow; Humans; Isometric Contraction; Male; Muscle, Skeletal; Myalgia; Torque; Young Adult

Joint range of motion (ROM) is an important parameter for athletic performance and muscular injury risk. Nonetheless, a complete description of muscular factors influencing ROM among individuals and between men and women is lacking. We examined whether passive muscle stiffness (evaluated by angle-specific muscle shear modulus), tolerance to muscle stretch (evaluated by muscle shear modulus at end-ROM), and muscle slack angle of the triceps surae are associated with the individual variability and sex difference in dorsiflexion ROM, using ultrasound shear wave elastography. For men, ROM was negatively correlated to passive muscle stiffness of the medial and lateral gastrocnemius in a tensioned state and positively to tolerance to muscle stretch in the medial gastrocnemius. For women, ROM was only positively correlated to tolerance to muscle stretch in all muscles but not correlated to passive muscle stiffness. Muscle slack angle was not correlated to ROM in men and women. Significant sex differences were observed only for dorsiflexion ROM and passive muscle stiffness in a tensioned state. These findings suggest that muscular factors associated with ROM are different between men and women. Furthermore, the sex difference in dorsiflexion ROM might be attributed partly to that in passive muscle stiffness of plantar flexors.

Topics: Adult; Ankle Joint; Elasticity; Elasticity Imaging Techniques; Female; Humans; Male; Muscle Strength Dynamometer; Muscle Tonus; Muscle, Skeletal; Myalgia; Range of Motion, Articular; Sex Factors; Tendons; Torque; Ultrasonography; Young Adult

The purpose of this study was to investigate the contralateral and ipsilateral repeated bout effects of eccentric contractions (ECCs) on muscle fiber activation using transverse relaxation time (T2) of magnetic resonance imaging (MRI).. Eleven men (22.3 ± 2.9 years) performed two bouts of 30 maximal ECCs of the elbow flexors spaced 2 weeks apart. Initially, all subjects performed 30 ECCs for one arm (ECC1). After 2 weeks, they performed 30 ECCs for both ipsilateral arm (IL-RBE) and contralateral arm (CL-RBE). Measurements were maximal voluntary isometric contraction (MVC) torque, range of motion (ROM), muscle soreness, cross-sectional area (CSA), and T2 at before, immediately after, 1, 2, 3, and 5 days after ECCs.. The loss of MVC torque, limited ROM, and developed muscle soreness and CSA were inhibited for IL-RBE and CL-RBE compared with ECC1 (p < 0.05). The acute T2, which is an indicator of the activation of muscle fibers, was longer for IL-RBE and CL-RBE than ECC1 (p < 0.05). Otherwise, no significant difference between IL-RBE and CL-RBE was observed in other measurements.. Our results suggest that one of the mechanisms for CL-RBE of ECCs is the increase in muscle fiber activation. In addition, the magnitude of protective effect for CL-RBE was similar to the IL-RBE in untrained young men.

Topics: Adult; Elbow; Elbow Joint; Electromyography; Exercise; Humans; Isometric Contraction; Male; Muscle Contraction; Muscle Strength; Muscle, Skeletal; Myalgia; Range of Motion, Articular; Torque; Young Adult

To describe the neuromuscular and perceptual responses to incline, decline or level treadmill exercise.. Fifteen healthy subjects performed on separate days 45 min treadmill exercise at 75% heart rate reserve in a level (+ 1% slope), incline (+ 15%) or decline condition (- 15%). Neuromuscular function of the knee extensors (KE) was assessed before and after exercise. Perception of effort, muscle pain and pleasure were measured during the exercise. Muscle pain was also reported up to 96 h after exercise.. At the same heart rate, the decline exercise was performed at a higher velocity. This higher velocity was associated with a higher perceived effort and muscle pain, as well as lower pleasure. Maximal isometric KE peak torque and maximal voluntary activation similarly decreased in the three conditions (~ 15 ± 12 and ~ 4 ± 4%). M-wave amplitude of the vastus medialis muscle decreased in the three conditions (~ - 12 ± 13%). M-wave amplitude of the rectus femoris muscle decreased only after the decline exercise (- 12 ± 16%). Peak twitch torque of the electrically evoked contractions was reduced after incline and decline exercises for both 10 and 100 Hz doublets (- 8 ± 9 and - 17 ± 18%). The Dt10/Dt100 ratio was reduced only after decline exercise (- 24 ± 19%).. At the same moderate intensity, decline exercise induced a greater level of muscle fatigue associated with a higher perceived effort and muscle pain than incline and level exercise. Exercise intensity should be carefully monitored during decline locomotion for training or rehabilitation purposes.

Topics: Adult; Electric Stimulation; Electromyography; Exercise; Exercise Test; Heart Rate; Humans; Knee; Knee Joint; Male; Muscle Contraction; Muscle Fatigue; Muscle, Skeletal; Myalgia; Torque

We tested the hypothesis that backward downhill walking (eccentric component) impairs both voluntary activation and muscle contractile properties in the plantar flexors and delays recovery as compared to a gradient and distance-matched uphill walk. Fourteen males performed two 30-min walking exercises (velocity: 1 m/ s; grade: 25%; load: 12% of body weight), one downhill (DW) and one uphill (UP), in a counterbalanced order, separated by 6 weeks. Neuromuscular test sessions were performed before, after, 24-, 48- and 72-h post-exercise, including motor nerve stimulations during brief (5 s) and sustained (1 min) maximal isometric voluntary contractions of the plantar flexors. DW (-18.1 ± 11.1%, P < .001), but not UP (-6.0 ± 7.7%, P =.15), decreased torque production during brief contractions for at least three days post-exercise (P < .05). Voluntary activation during brief contractions decreased after DW (P < .05), but not UP, and recovered by 24 h. Both UP (-9.3 ± 9.0%, P = .024) and DW (-25.6 ± 10.3%, P < .001) decreased torque production during sustained contractions but voluntary activation (P = .001) was lower in DW than UP. Peak twitch torque and maximum rates of torque development and relaxation were equally reduced after UP and DW (P < .05), and recovered by 24 h. DW induced an increase in muscle soreness with peak values observed 48 h post-walking (P < .001), whereas post-UP exercise changes were non-significant (all P > .05). Using a direct comparison, the capacity to drive the plantar flexors during sustained contractions remains sub-optimal during the three-day recovery period in response to non-exhaustive, downhill backward walking in reference to an uphill exercise matched for distance covered.

Topics: Adult; Biomechanical Phenomena; Electric Stimulation; Exercise Test; Gait; Humans; Isometric Contraction; Male; Muscle, Skeletal; Myalgia; Torque; Walking

Cooke, MB, Nix, C, Greenwood, L, and Greenwood, M. No Differences Between Alter G-Trainer and Active and Passive Recovery Strategies on Isokinetic Strength, Systemic Oxidative Stress and Perceived Muscle Soreness After Exercise-Induced Muscle Damage. J Strength Cond Res 32(3): 736-747, 2018-The incidence of muscle injuries is prevalent in elite sport athletes and weekend warriors and strategies that safely and effectively hasten recovery are highly desirable. The purpose of this study was to examine the differences between 3 recovery methods after eliciting muscle damage in recreationally active men relative to maximal isokinetic contractions, perceived muscle soreness, and psychological mood states. Twenty-five recreationally active men (22.15 ± 3.53 years, 75.75 ± 11.91 kg, 180.52 ± 7.3 cm) were randomly matched by V[Combining Dot Above]O2 peak (53.86 ± 6.65 ml·kg·min) and assigned to one of 3 recovery methods: anti-gravity treadmill (G-Trainer) (N = 8), conventional treadmill (N = 8) or static stretching (N = 9). Recovery methods were performed 30 minutes, 24, 48, and 72 hours after a 45-minute downhill run. Following eccentrically biased running, no significant differences were noted in isokinetic knee flexion and extension peak torque, systemic markers of muscle damage, oxidative stress and lipid peroxidation such as serum creatine kinase (CK), superoxide dismutase (SOD), and malondialdehyde (MDA), respectively, and subjective ratings of perceived muscle soreness between recovery methods. The G-Trainer group did however display a higher mood state as indicated by the Profile of Mood State global scores at 24 hours postexercise when compared to the conventional treadmill recovery group (p = 0.035). The improved mood state after the use of the anti-gravity treadmill may provide clinical relevance to other populations.

Topics: Adult; Creatine Kinase; Exercise; Exercise Test; Humans; Lipid Peroxidation; Male; Muscle Strength; Muscle, Skeletal; Myalgia; Oxidative Stress; Perception; Range of Motion, Articular; Recovery of Function; Running; Torque; Young Adult

Firstly, to establish whether oral contraceptive pill (OCP) users are more susceptible to muscle damage compared to non-users, and secondly, to establish whether differences can be attributed to differences in patella tendon properties.. Nine female OCP users and 9 female non-users participated in the investigation. Combining dynamometry, electromyography and ultrasonography, patella tendon properties and vastus lateralis architectural properties were measured pre and during the first of 6 sets of 12 maximal voluntary eccentric knee extensions. Serum oestrogen levels were measured on the 7th day of the pill cycle and the 14th day of menstrual cycle in OCP users and non-users, respectively. Maximal voluntary isometric knee extension torque loss, creatine kinase and muscle soreness were measured 48 h pre-damage, post-damage, and 48, 96 and 168 h post-damage.. Oestrogen levels were significantly lower in OCP users compared to non-users (209 ± 115 and 433 ± 147 pg/ml, respectively, p = 0.004). Proposed determinants of muscle damage, patella tendon stiffness and maximal eccentric torque did not differ between OCP users and non-users. The change in creatine kinase from pre to peak was significantly higher in OCP users compared to non-users (962 ± 968 and 386 ± 474 Ul, respectively, p = 0.016). There were no other differences in markers of muscle damage.. Although our findings suggest that, when compared to non-users, the OCP may augment the creatine kinase response following eccentric exercise, it does not increase the susceptibility to any other markers of muscle damage.

Topics: Adult; Case-Control Studies; Contraceptives, Oral; Creatine Kinase; Estrogens; Exercise; Female; Humans; Isometric Contraction; Muscle, Skeletal; Myalgia; Patellar Ligament; Torque

This study aimed to determine whether an increase in muscle shear modulus measured 30 min after eccentric exercise (30 min) reflects the magnitude of force deficit measured 48-h post-exercise (48 H).. A total of 53 healthy participants were distributed in five groups. Four groups performed either repeated eccentric elbow flexions or knee extensions at either a low or high load. A fifth group performed repeated concentric elbow flexions (control load).. A significant decreased peak torque was found for elbow flexors and knee extensors 48 h after the eccentric exercises (all P values < 0.001). A significant increase in shear modulus was found at 30 min for the elbow flexors for low (+70.5 ± 44.3%, P < 0.001) and high load (+153.9 ± 192.4%, P < 0.001). Similarly, the shear modulus of knee extensors increased for low (+26.7 ± 19.1%, P < 0.001) and high load (+79.4 ± 67.1%, P < 0.001). The relative increase in shear modulus measured at 30 min was significantly correlated to the relative decrease in peak torque measured at 48 H for both elbow flexors (r = -0.80) and knee extensors (r = -0.82). A further analysis suggested that biceps brachii and rectus femoris were more affected by muscle damage than their synergists.. This study shows that an increase in muscle shear modulus measured 30 min after a damaging exercise reflects the decrease in peak torque measured at 48 H. Shear modulus may therefore, provide a useful tool for coaches and clinicians to non-invasively estimate the amount of muscle damage induced by a damaging exercise.

Topics: Adult; Elasticity Imaging Techniques; Female; Humans; Isometric Contraction; Male; Muscle Strength; Myalgia; Physical Conditioning, Human; Torque

Exercise-induced muscle damage (EIMD) has been shown to reduce endurance exercise performance. This study examined the effects of EIMD on critical torque (CT) and the sum of the torque integral above CT during (∫. CT was determined in eight participants prior to and 48-h following EIMD. EIMD was induced using electrically stimulated eccentric knee extensions until maximal voluntary strength (MVC) was reduced by 40%. EIMD was assessed by changes in MVC and ratings of muscle soreness using a VAS scale. EMG and near-infrared spectroscopy (NIRS) were collected from the vastus lateralis and vastus medialis, respectively, during the CT test to assess neuromuscular electrical activity and microvascular circulation.. MVC decreased 22% (p = 0.006) and soreness increased from 2.1 ± 1.9 to 50.4 ± 31.5 mm (p = 0.002) 48-h following eccentric exercise. CT declined from 61.6 ± 17.8 to 52.0 ± 14.1 Nm (-14%; p = 0.005) post-EIMD. ∫

Topics: Adult; Exercise; Female; Humans; Isometric Contraction; Knee; Male; Muscle Fatigue; Muscle Strength; Muscle, Skeletal; Myalgia; Oxygen Consumption; Torque

This study aimed to analyze the acute effects of a judo training session on muscle strength, delayed-onset muscle soreness (DOMS), and serum creatine kinase (CK) activity.. Ten male judo athletes participated in this study and performed a 90-min traditional judo training session. The following measurements were performed before and 48 hours after the training: shoulder external/internal rotation isokinetic torque, countermovement jump (CMJ), DOMS, and blood draw for serum CK analysis. Student's t-test with significance level set at 5% and, effect size analysis were used.. Significant reduction was found in jump height in the CMJ after the training session (2.9%; moderate effect; P=0.02). No significant differences were observed in any of the measures of shoulder external/internal rotation isokinetic torque (P>0.05). An increase of the serum CK (49.4%; moderate effect; P=0.01) and DOMS (20.6%; large effect; P=0.003) were noted after the training session when compared to baseline.. Judo training session resulted in increased serum CK activity, and muscle soreness. The decrease of CMJ performance indicates impairment in the lower-limbs muscle power production. However, the lack of difference of shoulder external/internal rotation torque before and 48 hours after the training session may indicate that the interval was enough to recover the upper-limbs strength in judokas of this study. These markers of muscle damage can be used to control muscle adaptation progress and to avoid sports-related disorders of athletes with similar characteristics to those evaluated in this study.

Topics: Adult; Biomarkers; Creatine Kinase; Exercise; Humans; Male; Martial Arts; Muscle Strength; Muscle, Skeletal; Myalgia; Range of Motion, Articular; Shoulder Joint; Torque; Young Adult

Baroni, BM, Pompermayer, MG, Cini, A, Peruzzolo, AS, Radaelli, R, Brusco, CM, and Pinto, RS. Full range of motion induces greater muscle damage than partial range of motion in elbow flexion exercise with free weights. J Strength Cond Res 31(8): 2223-2230, 2017-Load and range of motion (ROM) applied in resistance training (RT) affect the muscle damage magnitude and the recovery time-course. Because exercises performed with partial ROM allow a higher load compared with those with full ROM, this study investigated the acute effect of a traditional RT exercise using full ROM or partial ROM on muscle damage markers. Fourteen healthy men performed 4 sets of 10 concentric-eccentric repetitions of unilateral elbow flexion on the Scott bench. Arms were randomly assigned to partial-ROM (50-100°) and full-ROM (0-130°) conditions, and load was determined as 80% of 1 repetition maximum (1RM) in the full- and partial-ROM tests. Muscle damage markers were assessed preexercise, immediately, and 24, 48, and 72 hours after exercise. Primary outcomes were peak torque, muscle soreness during palpation and elbow extension, arm circumference, and joint ROM. The load lifted in the partial-ROM condition (1RM = 19.1 ± 3.0 kg) was 40 ± 18% higher compared with the full-ROM condition (1RM = 13.7 ± 2.2 kg). Seventy-two hours after exercise, the full-ROM condition led to significant higher soreness sensation during elbow extension (1.3-4.1 cm vs. 1.0-1.9 cm) and smaller ROM values (97.5-106.1° vs. 103.6-115.7°). Peak torque, soreness from palpation, and arm circumference were statistically similar between conditions, although mean values in all time points of these outcomes have suggested more expressive muscle damage for the full-ROM condition. In conclusion, elbow flexion exercise with full ROM seems to induce greater muscle damage than partial-ROM exercises, even though higher absolute load was achieved with partial ROM.

Topics: Adolescent; Adult; Arm; Elbow Joint; Exercise; Humans; Male; Muscle, Skeletal; Myalgia; Range of Motion, Articular; Resistance Training; Torque; Young Adult

Roller massage (RM) has been reported to reduce pain associated with exercise-induced muscle soreness and increase range of motion without force or activation impairments. The objective was to examine RM effects on evoked pain and contractile properties.. Twelve men received three sets of 30-s RM at a perceived discomfort level of 7/10 on a visual analogue scale on the ipsilateral (IPSI-R) stimulated plantar flexors (PF), contralateral PF (CONTRA-R), Sham (light rolling on stimulated PF), or Control. At pre-test, post-test, and 5-min post-test, they received evoked maximal twitch, tetanus, and 70% maximal tetanic stimulation, and performed a maximal voluntary isometric contraction (MVIC). Data analysis included perceived pain and contractile properties.. The 70% tetanus illustrated significant 9-10% increases in pain perception with Sham and Control at post- and 5-min post-test, respectively (p < 0.01). There was no pain augmentation with IPSI-R and CONTRA-R. There were no main effects or interactions for most contractile properties. However, MVIC force developed in the first 200 ms showed 9.5% (p = 0.1) and 19.1% (p = 0.03) decreases with IPSI-R at post-test and 5-min post-test.. Data suggest that RM-induced neural inhibition decreased MVIC F200 and nullified the testing-induced increase in evoked pain associated with 70% tetanic stimulation.

Topics: Adult; Humans; Isometric Contraction; Male; Massage; Muscle, Skeletal; Myalgia; Neural Inhibition; Random Allocation; Torque

To examine the swelling response and other markers of muscle damage throughout the early portions of a training program (Experiment 1). We also determined if a "swollen" muscle could swell further following additional exercise (Experiment 2).. Nine males performed four sets of biceps curls (or time-matched rest on control arm) at 70% of their one-repetition maximum three times over 8 days. Muscle thickness and torque were measured before and after exercise as well as on the days in between. Soreness was measured at the beginning of each day (Experiment 1). On the final day (Experiment 2), participants performed two bouts of exercise, followed by additional measures of muscle thickness.. Following three bouts of exercise, muscle thickness was elevated over baseline (mean of visit 9 pre to visit 2 pre, 95% CI) at the 50% [0.21 (0.07, 0.34) cm], 60% [0.21 (0.02, 0.39) cm], and 70% [0.21 (0.06, 0.36) cm] sites. However, differences from a non-exercise control were only observed immediately following bouts of exercise (indicative of acute swelling). Torque was lower at every time point following the first bout of exercise and remained suppressed relative to pre at visit 9 [-6.1 (-11.7, -0.47 Nm] in the experimental arm. Experiment 2 found that a swollen muscle could not appreciably swell more.. Resting levels of muscle thickness do not appear to change beyond what occurs following the first naïve bout of exercise. Also, the acute swelling response may be used to differentiate swelling from muscle growth.

Topics: Adult; Arm; Exercise; Humans; Male; Muscle Contraction; Muscle Strength; Muscle, Skeletal; Myalgia; Random Allocation; Torque

The present study evaluated and compared the recovery of pectoralis major (PM) and triceps brachii (TB) muscles of trained men after bench press exercise.. Eighteen volunteers performed eight sets of bench press exercise to momentary muscle failure and were evaluated for TB and PM peak torque and total work on an isokinetic dynamometer.. PM peak torque and total work remained lower than baseline for 72 and 96 h, respectively. TB peak torque was only different from baseline immediately post training, while total work was significantly lower than baseline immediately and 48 h after training. Normalized peak torque values were only different between TB and PM at 48 h after training.. Considering the small and nonsignificant difference between the recovery of TB and PM muscles, the results suggest that bench press exercise may promote a similar stress on these muscles. Muscle Nerve 56: 963-967, 2017.

Topics: Adult; Electromyography; Exercise; Healthy Volunteers; Humans; Male; Muscle Strength; Myalgia; Pectoralis Muscles; Quadriceps Muscle; Resistance Training; Time Factors; Torque; Young Adult

Research regarding exercise-induced muscle-damage mainly focuses on adults. The present study examined exercise-induced muscle-damage responses in adults compared with children.. Eleven healthy boys (10-12 y) and 15 healthy men (18-45 y) performed 5 sets of 15 maximal eccentric contractions of the knee extensors. Range of motion (ROM), delayed onset muscle soreness (DOMS) during squat and walking, and peak isometric, concentric and eccentric torque were assessed before, post, 24, 48, 72, and 96 hr postexercise. Creatine kinase (CK) activity was assessed before and 72 hr postexercise.. Eccentric exercise resulted in DOMS during squat that persisted for up to 96h in men, and 48 hr in boys (p < .05), and DOMS during walking that persisted for up to 72 hr in men, and 48 hr in boys (p < .01). The ROM was lower in both age groups 48 hr postexercise (p < .001). Isometric (p < .001), concentric (p < .01) and eccentric (p < .01) force decreased post, and up to 48 hr postexercise in men. Except for a reduction in isometric force immediately after exercise, no other changes occurred in boys' isokinetic force. CK activity increased in men at 72 hr postexercise compared with pre exercise levels (p = .05).. Our data provide further confirmation that children are less susceptible to exercise-induced muscle damage compared with adults.

Topics: Adult; Child; Creatine Kinase; Exercise; Humans; Knee Joint; Male; Middle Aged; Muscle Strength; Muscle, Skeletal; Myalgia; Range of Motion, Articular; Torque; 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

Blood-flow restricted resistance exercise training (BFRE) is suggested to be effective in rehabilitation training, but more knowledge is required about its potential muscle damaging effects. Therefore, we investigated muscle-damaging effects of BFRE performed to failure and possible protective effects of previous bouts of BFRE or maximal eccentric exercise (ECC).. Seventeen healthy young men were allocated into two groups completing two exercise bouts separated by 14 days. One group performed BFRE in both exercise bouts (BB). The other group performed ECC in the first and BFRE in the second bout. BFRE was performed to failure. Indicators of muscle damage were evaluated before and after exercise.. The first bout in the BB group led to decrements in maximum isometric torque, and increases in muscle soreness, muscle water retention, and serum muscle protein concentrations after exercise. These changes were comparable in magnitude and time course to what was observed after first bout ECC. An attenuated response was observed in the repeated exercise bout in both groups.. We conclude that unaccustomed single-bout BFRE performed to failure induces significant muscle damage. Additionally, both ECC and BFRE can precondition against muscle damage induced by a subsequent bout of BFRE.

Topics: Humans; Male; Muscle Proteins; Muscle, Skeletal; Myalgia; Regional Blood Flow; Resistance Training; 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

To investigate whether there is a sex difference in exercise induced muscle damage.. Vastus Lateralis and patella tendon properties were measured in males and females using ultrasonography. During maximal voluntary eccentric knee extensions (12 reps x 6 sets), Vastus Lateralis fascicle lengthening and maximal voluntary eccentric knee extensions torque were recorded every 10° of knee joint angle (20-90°). Isometric torque, Creatine Kinase and muscle soreness were measured pre, post, 48, 96 and 168 hours post damage as markers of exercise induced muscle damage.. Patella tendon stiffness and Vastus Lateralis fascicle lengthening were significantly higher in males compared to females (p<0.05). There was no sex difference in isometric torque loss and muscle soreness post exercise induced muscle damage (p>0.05). Creatine Kinase levels post exercise induced muscle damage were higher in males compared to females (p<0.05), and remained higher when maximal voluntary eccentric knee extension torque, relative to estimated quadriceps anatomical cross sectional area, was taken as a covariate (p<0.05).. Based on isometric torque loss, there is no sex difference in exercise induced muscle damage. The higher Creatine Kinase in males could not be explained by differences in maximal voluntary eccentric knee extension torque, Vastus Lateralis fascicle lengthening and patella tendon stiffness. Further research is required to understand the significant sex differences in Creatine Kinase levels following exercise induced muscle damage.

Topics: Adult; Creatine Kinase; Elastic Modulus; Exercise; Female; Humans; Isometric Contraction; Knee Joint; Male; Muscle Contraction; Myalgia; Patellar Ligament; Quadriceps Muscle; Sex Factors; Torque; Ultrasonography; Young Adult

Eccentric contractions (ECCs) induce muscle damage that is indicated by prolonged loss of muscle function and delayed onset muscle soreness. It is possible that ECCs affect motor nerves, and this may contribute to the prolonged decreases in force generating capability. The present study investigated the hypothesis that M-wave latency of biceps brachii would be increased after maximal elbow flexor ECCs resulting in prolonged loss of muscle strength.. Fifteen women performed exercise consisting of 60 maximal ECCs of the elbow flexors using their non-dominant arm. M-wave latency was assessed by the time taken from electrical stimulation applied to the Erb's point to the onset of M-wave of the biceps brachii before, immediately after, and 1-4 days after exercise. Maximal voluntary isometric contraction (MVC) torque, range of motion (ROM) and muscle soreness using a numerical rating scale were also assessed before and after exercise.. Prolonged decreases in MVC torque (1-4 days post-exercise: -54 to -15 %) and ROM (1-2 days: -32 to -22 %), and increased muscle soreness (peak: 4.2 out of 10) were evident after exercise (p < 0.05). The M-wave latency increased (p < 0.01) from 5.8 ± 1.0 ms before exercise to 6.5 ± 1.7 ms at 1 day and 7.2 ± 1.5 ms at 2 days after exercise for the exercised arm only. No significant changes in M-wave amplitude were evident after exercise.. The increased M-wave latency did not fully explain the prolonged decreases in MVC torque after eccentric exercise, but may indicate reversible motor nerve impairment.

Topics: Adult; Arm; Elbow; Elbow Joint; Electric Stimulation; Electromyography; Exercise; Female; Humans; Isometric Contraction; Muscle Strength; Muscle, Skeletal; Myalgia; Range of Motion, Articular; Torque; Young Adult

This study aims to compare the isokinetic profile of hip abductor and adductor muscle groups between soccer players suffering from chronic adductor-related groin pain (ARGP), soccer players without ARGP and healthy volunteers from general population. Study included 36 male professional soccer players, who were randomly selected and followed-up over two years. Of the 21 soccer players eligible to participate in the study, 9 players went on to develop chronic ARGP and 12 players did not. Ten healthy male volunteers were randomly selected from the general population as a control group. Comparison between the abductor and adductor muscle peak torques for players with and without chronic ARGP found a statistically significant difference on the dominant and non-dominant sides (p < .005), with the abductor muscle significantly stronger than the adductor muscle. In the group of healthy volunteers, the adductor muscle groups were significantly stronger than the abductor muscle groups on both dominant and non-dominant sides (p < .05). For the group of players who had developed chronic ARGP, abductor-adductor torque ratios were significantly higher on the affected side (p = .008). The adductor muscle strength was also significantly decreased on the affected side. This imbalance appears to be a risk factor for adductor-related groin injury. Therefore, restoring the correct relationship between these two agonist and antagonist hip muscles may be an important preventative measure that should be a primary concern of training and rehabilitation programmes.

Topics: Adult; Athletes; Biomechanical Phenomena; Groin; Humans; Male; Muscle, Skeletal; Myalgia; Prospective Studies; Soccer; Torque; Young Adult

We investigated the responses of indirect markers of exercise-induced muscle damage (EIMD) among a large number of young men (N=286) stratified in clusters based on the largest decrease in maximal voluntary contraction torque (MVC) after an unaccustomed maximal eccentric exercise bout of the elbow flexors. Changes in MVC, muscle soreness (SOR), creatine kinase (CK) activity, range of motion (ROM) and upper-arm circumference (CIR) before and for several days after exercise were compared between 3 clusters established based on MVC decrease (low, moderate, and high responders; LR, MR and HR). Participants were allocated to LR (n=61), MR (n=152) and HR (n=73) clusters, which depicted significantly different cluster centers of 82%, 61% and 42% of baseline MVC, respectively. Once stratified by MVC decrease, all muscle damage markers were significantly different between clusters following the same pattern: small changes for LR, larger changes for MR, and the largest changes for HR. Stratification of individuals based on the magnitude of MVC decrease post-exercise greatly increases the precision in estimating changes in EIMD by proxy markers such as SOR, CK activity, ROM and CIR. This indicates that the most commonly used markers are valid and MVC orchestrates their responses, consolidating the role of MVC as the best EIMD indirect marker.

Topics: Adult; Cluster Analysis; Creatine Kinase; Elbow Joint; Exercise; Humans; Male; Muscle Contraction; Muscle, Skeletal; Myalgia; Range of Motion, Articular; Retrospective Studies; Torque; Young Adult

The repeated bout effect characterizes the protective adaptation after a single bout of unaccustomed eccentric exercise that induces muscle damage. Sarcomerogenesis and increased tendon compliance have been suggested as potential mechanisms for the repeated bout effect by preventing muscle fascicles from being stretched onto the descending limb of the length-tension curve (the region where sarcomere damage is thought to occur). In this study, evidence was sought for three possible mechanical changes that would support either the sarcomerogenesis or the increased tendon compliance hypotheses: a sustained rightward shift in the fascicle length-tension relationship, reduced fascicle strain amplitude, and reduced starting fascicle length.. Subjects (n = 10) walked backward downhill (5 km·h, 20% incline) on a treadmill for 30 min on two occasions separated by 7 d. Kinematic data and medial gastrocnemius fascicle lengths (ultrasonography) were recorded at 10-min intervals to compare fascicle strains between bouts. Fascicle length-torque curves from supramaximal tibial nerve stimulation were constructed before, 2 h after, and 2 d after each exercise bout.. Maximum torque decrement and elevated muscle soreness were present after the first, but not the second, backward downhill walking bout signifying a protective repeated bout effect. There was no sustained rightward shift in the length-torque relationship between exercise bouts, nor decreases in fascicle strain amplitude or shortening of the starting fascicle length.. Protection from a repeated bout of eccentric exercise was conferred without changes in muscle fascicle strain behavior, indicating that sarcomerogenesis and increased tendon compliance were unlikely to be responsible. As fascicle strains are relatively small in humans, we suggest that changes to connective tissue structures, such as extracellular matrix remodeling, are better able to explain the repeated bout effect observed here.

Topics: Adaptation, Physiological; Adult; Biomechanical Phenomena; Female; Humans; Male; Muscle, Skeletal; Myalgia; Sarcomeres; Sprains and Strains; Tendons; Torque; Walking; Young Adult

A single bout of eccentric exercise confers a protective effect against muscle damage and soreness in subsequent eccentric exercise bouts, but the mechanisms underpinning this effect are unclear.. This study compared vastus lateralis (VL) muscle-tendon behavior between two eccentric cycling bouts to test the hypothesis that muscle-tendon behavior would be different between bouts and would be associated with the protective effect.. Eleven untrained men (27.1 ± 7.0 yr) performed two bouts of eccentric cycling (ECC1 and ECC2) separated by 2 wk for 10 min at 65% of maximal concentric workload (191.9 ± 44.2 W) each. Muscle soreness (by visual analog scale) and maximal voluntary isometric contraction (MVC) torque of the knee extensors were assessed before and 1-2 d after exercise. Using ultrasonography, VL fascicle length and angle changes during cycling were assessed, and tendinous tissue (TT) length changes were estimated. VL EMG amplitude, crank torque, and knee joint angles were measured during cycling.. Soreness was greater (P < 0.0001) after ECC1 than ECC2, although MVC changes were not different between bouts (P = 0.47). No significant differences in peak EMG amplitude (normalized to EMG during MVC), crank peak torque, or knee angles were evident between bouts. However, fascicle elongation was 16% less during ECC2 than ECC1 (P < 0.01), indicating less fascicle strain in ECC2. Maximum TT length occurred at a smaller knee joint angle during ECC2 than ECC1 (P = 0.055).. These results suggest that a lesser fascicle elongation and earlier TT elongation were associated with reduced muscle soreness after ECC2 than ECC1; thus, changes in muscle-tendon behavior may be an important mechanism underpinning the protective effect.

Topics: Adult; Bicycling; Electromyography; Exercise; Humans; Isometric Contraction; Knee; Male; Muscle Contraction; Myalgia; Quadriceps Muscle; Range of Motion, Articular; Tendons; Time Factors; Torque; Ultrasonography; Young Adult

The aim of this study was to examine the effect of low muscle glycogen on the neuromuscular responses to maximal eccentric contractions. Fourteen healthy men (22 ± 3 years) performed single-leg cycling (20 min at ~75% maximal oxygen uptake (V̇O2 max); eight 90 s sprints at a 1:1 work-to-rest ratio (5% decrements from 90% to 55% V̇O2 max until exhaustion) the evening before 100 eccentric (1.57 rads(-1)) with reduced (RED) and normal glycogen (NORM). Neuromuscular responses were measured during and up to 48 h after with maximal voluntary and involuntary (twitch, 20 Hz and 50 Hz) isometric contractions. During eccentric contractions, peak torque decreased (RED: -16.1 ± 2.5%; NORM: -6.2 ± 5.1%) and EMG frequency increased according to muscle length. EMG activity decreased for RED only. After eccentric contractions, maximal isometric force was reduced up to 24h for NORM (-13.5 ± 5.8%) and 48 h for RED (-7.4 ± 10.9%). Twelve hours after eccentric contractions, twitch force and the 20:50 Hz ratio were decreased for RED but not for NORM. Immediate involuntary with prolonged voluntary force loss suggests that reduced glycogen is associated with increased susceptibility to mild muscle-damaging eccentric exercise with contributions of peripheral and central mechanisms to be different during recovery.

Topics: Adult; Electromyography; Exercise; Glycogen; Humans; Isometric Contraction; Male; Muscle Fatigue; Muscle, Skeletal; Myalgia; Torque

This study compared responses to static stretching between eccentrically damaged and non-damaged muscles.. Twelve young men performed 60 maximum knee flexor eccentric contractions of one leg, and received a 300-s continuous passive static stretching at tolerable intensity without pain to both knee flexors at 2 and 4 days after the eccentric exercise. Range of motion (ROM) and passive stiffness during knee extension, passive torque at onset of pain (PT), maximum voluntary isometric (MVC-ISO) and isokinetic concentric contraction torque (MVC-CON), and visual analogue scale (VAS) for muscle soreness were measured before, immediately after, 60 min, 2 and 4 days after exercise as well as before, immediately after, 20 and 60 min after the stretching. Changes in these variables after eccentric exercise and stretching were compared between limbs.. The eccentric exercise decreased MVC-ISO, MVC-CON, ROM and PT, and increased passive stiffness and VAS (p < 0.05), suggesting that muscle damage was induced to the knee flexors. ROM and PT increased after stretching for both limbs; however, the magnitude of the increase was greater (p < 0.05) for the damaged than non-damaged limb. Passive stiffness decreased for both limbs similarly (4-7 %) at immediately after stretching (p < 0.05). Significant decreases in MVC-ISO torque (7-11 %) after stretching were observed only for the non-damaged limb (p < 0.05), but MVC-CON torque did not change after stretching for both limbs. VAS decreased for the exercised limb after stretching (p < 0.05).. These results suggest that the static stretching at tolerable intensity without pain produced greater positive effects on damaged than non-damaged muscles.

Topics: Exercise; Humans; Isometric Contraction; Male; Muscle Stretching Exercises; Muscle, Skeletal; Myalgia; Range of Motion, Articular; Thigh; Torque; Young Adult

A single bout of unaccustomed exercise confers protective effect against muscle damage from a subsequent bout of similar activity, that is, repeated bout effect (RBE). It remains unknown whether varying muscle-specific exercise between sessions alters the magnitude of the RBE. This study examined the effects of muscle-specific exercise variation between consecutive sessions on the RBE. Twenty untrained males (21 ± 2 years) were assigned to one of 2 groups (n = 10 per group): (a) 2 sessions of incline curls, Fixed Exercise or (b) 1 session of incline curls followed by 1 session of preacher curls, Varied Exercise, with 7 days between sessions. Subjects performed 5 sets of 6 repetitions at ∼50% of maximal isometric elbow flexor strength during each session. Changes in maximal voluntary isometric and isokinetic torque, range of motion, muscle soreness, and serum creatine kinase were measured before, immediately after, and 24, 48, 72, and 96 hours after each exercise session, and the changes were compared between bouts and between groups. There were significant time effects (p < 0.05) for isometric maximal voluntary contraction, concentric maximal voluntary contraction, range of motion, and muscle soreness during sessions 1 and 2 with no between-group differences. Both groups demonstrated a significantly faster recovery of range of motion and soreness to baseline levels after session 2 compared with session 1. Overall, our findings suggest that incline curls conferred a protective effect during subsequent preacher curls in a similar way to repeating incline curls; therefore, the RBE was not exercise specific.

Topics: Adolescent; Creatine Kinase; Elbow Joint; Exercise; Humans; Isometric Contraction; Male; Muscle, Skeletal; Myalgia; Range of Motion, Articular; Recovery of Function; Resistance Training; Time Factors; Torque; Young Adult

Delayed-onset muscle soreness (DOMS) is a common muscle pain that many people experience and is often used as a model of acute muscle pain. Researchers have reported the effects of various interventions on DOMS, but different DOMS assessment protocols used in these studies make it difficult to compare the effects.. To investigate DOMS characteristics after elbow-flexor eccentric exercise to establish a standardized DOMS assessment protocol.. Descriptive laboratory study.. Research laboratory.. Ten healthy, untrained men (21-39 years).. Participants performed 10 sets of 6 maximal isokinetic eccentric contractions of the elbow flexors.. Indirect muscle-damage markers were maximal voluntary isometric contraction torque, range of motion, and serum creatine kinase activity. Muscle pain was assessed before exercise, immediately postexercise, and 1 to 5 days postexercise using (1) a visual analog scale (VAS), (2) a category ratio-10 scale (CR-10) when applying static pressure and palpation at different sites (3, 9, and 15 cm above the elbow crease), and (3) pressure-pain thresholds (PPTs) at 50 sites (pain mapping).. Maximal voluntary isometric contraction and range of motion decreased and creatine kinase activity increased postexercise, indicating muscle damage. Palpation induced greater pain than static pressure, and longitudinal and transverse palpations induced greater pain than circular palpation (P < .05). The PPT was lower in the medial region before exercise, but the pain-sensitive regions shifted to the central and distal regions of the biceps brachii at 1 to 3 days postexercise (P < .05). The VAS was correlated with the CR-10 scale (r = 0.91, P < .05) but not with the PPT (r = -0.28, P = .45).. The way in which muscles are assessed affects the pain level score. This finding suggests that pain level and pain threshold cannot be used interchangeably and that the central and distal regions of the biceps brachii should be included in DOMS assessment using the VAS, CR-10 scale, and PPT after elbow-flexor eccentric exercise.

Topics: Adult; Arm; Elbow; Elbow Joint; Exercise; Humans; Isometric Contraction; Male; Muscle, Skeletal; Myalgia; Pain Measurement; Pain Threshold; Range of Motion, Articular; Torque; Young Adult

The purpose of this study was to determine if a moderate intensity whole-body vibration (WBV) body mass resistive exercise session causes additional muscle damage, soreness, and inflammation compared with the same exercise session without vibration (NoV). Ten recreationally active male university students completed 2 separate 24-hour study periods incorporating an exercise session with WBV or NoV. Muscle torque was measured (at 0, 60, and 240°·s-1 angular velocities), soreness (10-point scale) in the upper (UE [triceps]) and lower (LE [quadriceps]) extremities, and muscle inflammation markers (interleukin [IL]-1β, IL-6, IL-10) were measured at 4 time points (preexercise, immediately postexercise, 4 hours post, and 24 hours post). Diet was controlled. Compared with NoV, WBV increased (p < 0.01) muscle soreness at 24 hours postexercise in both the UE (2.2 ± 1.7 vs. 0.6 ± 0.9) and LE (2.0 ± 1.5 vs. 0.7 ± 0.7). Muscle torque was decreased immediately postexercise (p < 0.05) in the UE and LE at 0°·s and in the UE at 240°·s, but there was no difference between exercise treatments. The exercise session caused significant but small increases in IL-1β and IL-6 but with no differences between exercise treatments. Interleukin-10 was increased with WBV (2.9 ± 2.0 to 3.6 ± 1.9 pg·ml-1; p < 0.03). These data suggest that the addition of WBV to exercise has little effect on muscle function and damage, soreness, or inflammation.

Topics: Adult; Arm; Biomechanical Phenomena; Humans; Interleukin-10; Interleukin-1beta; Interleukin-6; Isometric Contraction; Male; Myalgia; Myositis; Physical Conditioning, Human; Quadriceps Muscle; Resistance Training; Torque; Vibration; Young Adult

This study aimed to test the reproducibility of running performance, neuromuscular fatigue markers and indirect muscle damage indicators in a field-based trail time-trial.. Running performance and changes in classical physiological parameters were analysed in 11 experienced trail runners before and in the days following four bouts of outdoor trail running (15.6 km), 7 days apart.. Heart rate, running time and lactate concentration were monitored in each running bout. Maximal voluntary contraction torque, counter movement jump height, plasma creatine kinase activity and muscle soreness were assessed before and 1, 24 and 48 h post-race. Within-bout changes were elucidated using a two-way repeated measures ANOVA. Inter-repetition reproducibility was examined using an intraclass correlation coefficient (R) and the mean intra-subject coefficient of variation at each measurement time point.. Running time was longer (p<0.05) for the first bout compared with the other three bouts. Magnitude and time course of changes in counter movement jump height, creatine kinase activity and muscle soreness were similar among all four bouts (overall peak means: -17%, +35% and 54/100mm respectively). The acute reduction in maximal voluntary contraction torque (peak mean: -17%) was attenuated exclusively in the fourth bout (p<0.05). The two middle bouts showed good reproducibility (intraclass correlation coefficient and coefficient of variation) for running time, maximal voluntary contraction torque and counter movement jump height, but low to moderate for creatine kinase activity, muscle soreness, blood lactate and rate of perceived exertion.. A short outdoor trail run is a reliable model for investigations of fatigue and muscle damage, but certain methodological precautions should be respected.

Topics: Adult; Athletic Performance; Creatine Kinase; Heart Rate; Humans; Lactic Acid; Male; Muscle Contraction; Muscle Fatigue; Muscle, Skeletal; Myalgia; Physical Exertion; Reproducibility of Results; Running; Time Factors; Torque; Young Adult

Our study aimed to determine whether electrical and mechanical factors contributing to acute or long-term maximal torque reduction and muscle soreness due to submaximal eccentric exercise (ECC) are elbow-joint-angle specific and to what extent the joint angle affects the contribution of antagonist coactivation to this torque reduction. Maximal isometric torque (MIT), muscle soreness assessment, agonist electromechanical activities, and antagonist coactivation during the maximal voluntary contraction (MVC) were measured at elbow joint angles of 60°, 90°, and 150° before ECC, immediately after exercise, and 24, 48, 72, and 120 hr after exercise. ECC causes an immediate decrease in MIT as well as increased antagonist coactivation at three angles. Antagonist coactivation returned to its baseline level at 24 hr regardless of joint angle. The most rapid torque recovery and the highest force level at which pain occurred were found after ECC at a joint angle of 60°. During the recovery period, no mechanomyographical changes were observed when measuring surface mechanomyography changes at three angles, while the electrical activity differed between angles.

Topics: Adult; Analysis of Variance; Elbow Joint; Electromyography; Exercise; Humans; Isometric Contraction; Male; Muscle Contraction; Muscle, Skeletal; Myalgia; Posture; Rest; Torque; Young Adult

We examined the susceptibility of fast and slow twitch muscle fibers in the quadriceps muscle to eccentric exercise-induced muscle damage. Nine healthy men (age: 22.5 ± 1.6 years) performed maximal eccentric quadriceps contractions at 120°·s-1 over a 120° of knee joint range of motion for 6 consecutive days. Biopsies were taken from the vastus lateralis muscle before repeated bouts of eccentric exercise on the third and seventh day. Immunohistochemical procedures were used to determine fiber composition and fibronectin activity. Creatine kinase (CK) and lactate dehydrogenase (LDH) were determined in serum. Average torque was calculated in each day for each subject. Relative to baseline, average torque decreased 37.4% till day 3 and increased 43.0% from the day 3 to day 6 (p < 0.001). Creatine kinase and LDH were 70.6 and 1.5 times higher on day 3 and 75.5 and 1.4 times higher on day 6. Fibronectin was found in fast fibers in subjects with high CK level on day 3 and 7 after exercise, but on day 7, fibronectin seemed in both slow and fast fibers except in muscles of 2 subjects with high fast fiber percentage. Peak torque and muscle fiber-type composition measured at baseline showed a strong positive association on day 3 (r = 0.76, p < 0.02) and strong negative association during recovery between day 3 and day 6 (r = -0.76, p < 0.02), and day 1 and day 6 (r = 0.84, p < 0.001). We conclude that the damage of fast fibers preceded the damage of slow fibers, and muscles with slow fiber dominance were more susceptible to repeated bouts of eccentric exercise than fast fiber dominance muscles. The data suggest that the responses to repeated bouts of eccentric exercise are fiber-type-dependent in the quadriceps muscle, which can be the basis for the design of individualized strength training protocols.

Topics: Creatine Kinase; Exercise; Fibronectins; Humans; L-Lactate Dehydrogenase; Male; Muscle Contraction; Muscle Fibers, Fast-Twitch; Muscle Fibers, Slow-Twitch; Myalgia; Quadriceps Muscle; Time Factors; Torque; Young Adult

Contraction-induced muscle injury may reduce running economy (RE) by altering motor unit recruitment, lowering contraction economy, and disturbing running mechanics, any of which may have a deleterious effect on endurance performance. The purpose of this study was to determine if RE is reduced 2 days after performing injurious, low-intensity exercise in 11 healthy active men (27.5 ± 5.7 years; 50.05 ± 1.67 VO2peak). Running economy was determined at treadmill speeds eliciting 65 and 75% of the individual's peak rate of oxygen uptake (VO2peak) 1 day before and 2 days after injury induction. Lower extremity muscle injury was induced with a 30-minute downhill treadmill run (6 × 5 minutes runs, 2 minutes rest, -12% grade, and 12.9 km·h(-1)) that elicited 55% VO2peak. Maximal quadriceps isometric torque was reduced immediately and 2 days after the downhill run by 18 and 10%, and a moderate degree of muscle soreness was present. Two days after the injury, steady-state VO2 and metabolic work (VO2 L·km(-1)) were significantly greater (4-6%) during the 65% VO2peak run. Additionally, postinjury VCO2, VE and rating of perceived exertion were greater at 65% but not at 75% VO2peak, whereas whole blood-lactate concentrations did not change pre-injury to postinjury at either intensity. In conclusion, low-intensity downhill running reduces RE at 65% but not 75% VO2peak. The results of this study and other studies indicate the magnitude to which RE is altered after downhill running is dependent on the severity of the injury and intensity of the RE test.

Topics: Adult; Carbon Dioxide; Humans; Lactic Acid; Male; Muscle Contraction; Myalgia; Oxygen Consumption; Physical Exertion; Pulmonary Ventilation; Quadriceps Muscle; Running; Torque; Young Adult

This study examined the impact of eccentric exercise-induced muscle damage on the rate of adjustment in muscle deoxygenation and pulmonary O2 uptake (VO(2p)) kinetics during moderate exercise.. Fourteen males (25 ± 3 year; mean ± SD) completed three step transitions to 90 % θL before (Pre), 24 h (Post24) and 48 h after (Post48) eccentric exercise (100 eccentric leg-press repetitions with a load corresponding to 110 % of the participant's concentric 1RM). Participants were separated into two groups: phase II VO(2p) time constant (τVO(2p)) ≤ 25 s (fast group; n = 7) or τVO(2p) > 25 s (slow group; n = 7). VO(2p) and [HHb] responses were modeled as a mono-exponential.. In both groups, isometric peak torque (0°/s) at Post24 was decreased compared to Pre (p < 0.05) and remained depressed at Post48 (p < 0.05). τVO(2p) was designed to be different (p < 0.05) at Pre between the Fast (τVO(2p); 19 ± 4 s) and Slow (32 ± 6 s) groups. There were no differences among time points (τVO(2p): Pre, 19 ± 4 s; Post24, 22 ± 3 s; Post48, 20 ± 4 s) in the Fast group. In Slow, there was a speeding (p < 0.05) from the Pre (32 ± 6 s) to the Post24 (25 ± 6) but not Post48 (31 ± 6), resulting in no difference (p > 0.05) between groups at Post24. This reduction of τVO(2p) was concomitant with the abolishment (p < 0.05) of an overshoot in the [HHb]/VO(2p) ratio.. We propose that the sped VO(2p) kinetics observed in the Slow group coupled with an improved [HHb]/VO(2p) ratio suggest a better matching of local muscle O2 delivery to O2 utilization following eccentric contractions.

Topics: Adult; Case-Control Studies; Exercise; Humans; Isometric Contraction; Male; Muscle, Skeletal; Myalgia; Oxygen; Oxygen Consumption; Torque

To determine the acute task and stretch-load dependency of neuromuscular impairments after muscle-damaging exercises, we examined the magnitude of strength deficits in isometric and stretch-shortening cycle (SSC) contractions after a single bout of exercise. Ten trained men performed 90 unilateral isokinetic eccentric-concentric knee extensions on a dynamometer. Plasma creatine kinase activity, muscle soreness, maximal isometric torque, short-range stiffness, and peak torque in the eccentric phase of the SSC contraction at 3 stretch-loads (120, 150, and 180 J) were determined in the quadriceps before and 24 hours after exercise. During SSC, positive mechanical work and efficiency were also calculated. Creatine kinase and soreness increased at 24 hours (p < 0.05). In each of the 3 stretch-load conditions, muscle damage affected short-range stiffness less than isometric and peak SSC torque (p < 0.05), providing evidence for a selective impairment in contractile function after muscle damage. With greater SSC stretch-load peak, SSC torque deficit increased linearly, whereas short-range stiffness deficit was unaffected. Efficiency declined only at the 180-J condition (p < 0.05) as a result of decreased positive work (p < 0.05). It was concluded that intense exercise produced microtrauma in the muscle, and a selective loss of force generating capacity, which suggests greater damage to the contractile machinery. Practitioners may expect greater acute impairment of force generation in movements that use large loads in their daily training drills. However, altered knee flexion strategy during SSC may compensate for the force deficit, preserving mechanical efficiency at smaller stretch-loads.

Topics: Adolescent; Adult; Creatine Kinase; Humans; Isometric Contraction; Male; Myalgia; Physical Conditioning, Human; Physical Exertion; Quadriceps Muscle; Torque; Young Adult