Eccentric Peak Torque Research Articles

Eccentric training combined to neuromuscular electrical stimulation is not superior to eccentric training alone for quadriceps strengthening in healthy subjects: a randomized controlled trial

BackgroundBoth eccentric training and neuromuscular electrical stimulation (NMES) are used for quadriceps strengthening. However, the effects of these interventions combined are unclear. ObjectivesTo compare the effects of eccentric training combined to NMES and eccentric training alone on structure, strength, and functional performance of knee extensor muscles of healthy subjects. MethodsThis is a three-arm, single-blinded, randomized controlled trial. Forty-three volunteers (18–35 years) completed the full study schedule: control group (n=15); eccentric training group (ECC; n=15); and eccentric training combined to NMES group (ECC+NMES; n=13). Eccentric training program was performed twice a week for 6 weeks. A biphasic pulsed current (400μs; 80Hz; maximal tolerated intensity) was applied simultaneously to voluntary exercise for ECC+NMES group. Muscle structure (ultrasonography of vastus lateralis – VL, and rectus femoris – RF), strength (isokinetic dynamometry) and functional capacity (single hop test) were assessed before and after the training program by blinded researchers to groups allocation. ResultsControl group had no changes throughout the study in any outcome. Eccentric training (with or without NMES) did not affect concentric peak torque, hop test, and VL pennation angle (effect sizes>0.2). ECC and ECC+NMES programs generated significant adaptations (small to moderate effect sizes) on isometric (8–11%) and eccentric (13%) peak torques, VL muscle thickness (5%), VL fascicle length (5–8%), RF muscle thickness (8–9%), RF pennation angle (−2%), and RF fascicle length (12%). ConclusionNMES combined to eccentric training did not influence consistently the type or magnitude of adaptations provoked by knee extensor eccentric training alone in healthy subjects.

Running fatiguing protocol affects peak torque joint angle and peak torque differently in hamstrings vs. quadriceps

The aim of the current study was to investigate the effects of a running fatiguing protocol on the peak torque joint angle and the peak torque in hamstrings vs. quadriceps. Twenty-one male runners underwent a running fatiguing protocol consisting of 40 min at a speed corresponding at first ventilatory threshold. Before and after the fatiguing protocol, isokinetic concentric and eccentric hamstrings and concentric quadriceps peak torque was measured at 60 and 300 deg s−1. The peak torque joint angle (i.e. the angle at which the peak torque was exerted) was recorded. The conventional Hconc:Qconc ratio and the functional Hecc:Qconc ratio were also calculated. The peak torque joint angle increased (i.e. shifted toward shorter muscle length) in hamstrings in eccentric at 60 deg s−1 (ES = 1.35) and at 300 deg s−1 (ES = 0.71) and in concentric modality at 300 deg s−1 (ES = 0.50) but not at 60 deg s−1 (ES = 0.23). No change occurred in quadriceps at 60 deg s−1 (ES = 0.15) and 300 deg s−1 (ES = 0.20). Peak torque deteriorated in both hamstrings and quadriceps, irrespective of the testing modality (ES 0.95–1.90) Functional Hecc:Qconc ratio decreased at 60 deg s−1 (ES = 0.74) and 300 deg s−1 (ES = 0.85). No change in conventional Hconc:Qconc ratio occurred at 60 deg s−1 (ES = 0.12) and 300 deg s−1 (ES = 0.14). The fatigue-induced changes in peak torque joint angle in hamstrings but not in quadriceps and the simultaneous decrements in the functional Hecc:Qconc ratio may point a reduced hamstrings resistive capacity, with implications for hamstrings strain injury risk.

The long-term effects of static stretching at different times of day on hamstring peak torque and flexibility in trained individuals

PurposeThere is some recent evidence that temporal specificity is important for optimizing training for muscular performance. This study was to examine the long-term effects of static stretching performed at different times of day on hamstring torque and flexibility.MethodsThe total of 60 trained male subjects with tight hamstring were selected and randomly divided into 3 equal groups. Group A received static stretch in the morning (07:00–9:00), group B in the afternoon (13:00–16:00), and group C in the evening (18:00–20:00). The hamstring isokinetic concentric and eccentric peak torque and knee extension range of motion were assessed before and after 6 weeks of static stretching (3 repetitions of 30 s, 5 times/week).ResultsA statistically significant increase was observed in hamstring concentric and eccentric torque, and flexibility after static stretching at different times of day (<i>p</i> < 0.05). The concentric and eccentric torque post-training values were significantly higher than the pre-training values (<i>p</i> < 0.05). The hamstring flexibility post-training values of groups B and C were significantly higher than for group A (<i>p</i> < 0.05). The torque and flexibility change scores of groups B and C were significantly higher than for group A (<i>p</i> < 0.05), without any significant difference between groups B and C (<i>p</i> > 0.05).ConclusionsAfternoon and evening static stretching is more effective than morning stretching in improving the hamstring concentric and eccentric torque and flexibility. Therefore, static stretching is a time-dependent task and should be scheduled by clinicians, coaches, and athletes in the afternoon or evening.

Effects of preconditioning hamstring resistance exercises on repeated sprinting-induced muscle damage in female soccer players.

To examine whether adding preconditioning hamstring resistance exercises to a regular warm-up prior to a repeated sprinting exercise provides protection against the sprinting-induced muscle damage. Ten female soccer players (mean ± SD age: 21.3 ± 4.5yrs; height: 171.34 ± 8.29 cm; weight: 68.53 ± 11.27 kg) participated in this study. After the familiarization visit, the subjects completed three separate randomly sequenced experimental visits, during which three different warm-up interventions were performed before the muscle-damaging protocol (12 sets of 30-m maximal repeated sprints): 1. Regular running and static stretching (Control); 2. Control with hyperextensions (HE); 3. Control with single leg Romanian deadlift (SLRD). Before (Pre), immediately (Post0), 24 hours (24hr), and 48 hours after (48hr) the sprints, hamstring muscle thickness, muscle stiffness, knee flexion eccentric peak torque, knee extension concentric peak torque, and functional hamstring to quadriceps ratios were measured. Repeated sprints have induced muscle damage (e.g., an average of 42% knee flexion eccentric strength reduction) in all three conditions. After the SLRD, hamstring muscle thickness decreased from 24hr to 48hr (p < 0.001). Additionally, muscle stiffness and eccentric strength for the SLRD showed no difference from baseline at 24hr and 48hr, respectively. When compared with the SLRD at 48hr, the muscle stiffness and the eccentric strength were greater and lower, respectively, in other protocols. The SLRD protocol had protective effect on sprinting-induced muscle damage markers than other protocols. Athletes whose competitions/training are densely scheduled may take advantage of this strategy to facilitate muscle recovery.

The Contributions of Arterial Cross-Sectional Area and Time-Averaged Flow Velocity to Arterial Blood Flow.

Background:Ultrasound has been used for noninvasive assessments of endothelial function in both clinical and athletic settings and to identify changes in muscle blood flow in response to exercise, nutritional supplementation, and occlusion. The purposes of the present study were to examine the reliability and relative contributions of arterial cross-sectional area and time-averaged flow velocity to predict muscle blood flow as a result of fatiguing exercise in men and women.Methods:Eighteen healthy men and 18 healthy women performed 50 consecutive eccentric repetitions of the elbow flexors at 60% of their pretest eccentric peak torque at a velocity of 180° s−1. Test-retest reliability and stepwise linear regression analyses were performed to determine the ability of arterial cross-sectional area and time-averaged flow velocity to predict brachial artery muscle blood flow for the men, women, and combined sample.Results:There was no systematic test versus retest mean differences (P > 0.05) for any of the ultrasound determined variables. The two-variable regression models significantly improved the ability to predict muscle blood flow and were associated with smaller standard error of the estimates (3.7%–10.1% vs. 16.8%–37.0% of the mean baseline muscle blood flow values) compared to the one-variable models.Conclusions:The findings of the present study supported the use of ultrasound for reliable assessments of arterial diameter, arterial cross-sectional area, time-averaged flow velocity, and muscle blood flow from the brachial artery in men and women. Furthermore, time-averaged flow velocity was a more powerful predictor of muscle blood flow than arterial cross-sectional area.

Eccentric hamstring strength deficit and poor hamstring-to-quadriceps ratio are risk factors for hamstring strain injury in football: A prospective study of 146 professional players

ObjectivesThe purpose of this study was to investigate whether preseason isokinetic strength measures were predictive of future HSI among professional football players. DesignProspective cohort study, Level of evidence 2. MethodsA total of 169 professional players participated in a preseason isokinetic strength screening, followed by a 10-month competitive season. Testing protocol included the concentric performance of both knee flexion and extension at 60degs−1 and 240degs−1 and the eccentric performance of the knee flexor at 30degs−1. Strength deficits, bilateral differences, and hamstring to quadriceps strength ratios were computed. Univariate and multivariate logistic regressions were used to identify potential risk factors of HSI. Receiver operating characteristic (ROC) curves were used to investigate the sensitivity and specificity of the strength measures. ResultsForty-one acute HSIs were sustained, and 12% (n=5) reoccurred within the study period. In the multivariate analysis, we have shown an association between the injury risk and eccentric hamstring peak torque below 2.4Nmkg−1 (OR=5.59; 95% CI, 2.20–12.92); concentric H/Q ratio below 50.5% (OR=3.14; 95% CI, 1.37–2.22); players with previous injury of HSI (OR=3.57; 95% CI, 3.13–8.62). ROC analysis displayed an area under curve (AUC) of 0.77, indicating fair combined sensitivity and specificity of the overall predicting model. ConclusionsProfessional football players with significant lower isokinetic hamstring strength, lower hamstring-to-quadriceps strength ratio, and a previous injury of HSI were linked to an increased risk of acute HSI.

Isokinetic Performance of Knee Flexor and Extensor Muscles in American Football Players from Brazil

DOI: http://dx.doi.org/10.5007/1980-0037.2017v19n4p426 The isokinetic performance of thigh muscles has been related to athletic performance and risk for non-contact injuries, such as anterior cruciate ligament ruptures and hamstring strains. Although isokinetic profile of American football players from United States (USA) is widely described, there is a lack of studies comprising players acting outside the USA. The primary objective of this study was to describe the isokinetic performance of thigh muscles in elite American football players in Brazil. Secondarily, we aimed to compare the playing positions and compare the Brazilian players with high-level athletes from USA. Knee extensor (KE) and flexor (KF) muscles of 72 Brazilian players were assessed through isokinetic tests at 60°·s-1. KE concentric peak torque was 276±56 N·m, while KF had concentric and eccentric peak torques of 151±37 N·m and 220±40 N·m, respectively. Offensive linemen players presented greater peak torque values than defensive lineman, halfbacks, and wide receivers (all comparisons are provided in the article). Brazilian players had lower scores than USA athletes for KE and KF peak torque values. In addition, a conventional torque ratio (concentric/concentric) lower than 0.6 was found in 76-83% of athletes, and a functional ratio (eccentric/eccentric) below to 1.0 in 94%. Bilateral asymmetry greater than 10% was verified in 26% and 43% of athletes for KE and KF muscles, respectively. Elite players in Brazil present high incidence of strength imbalance in thigh muscles, and they are below USA players in relation to torque production capacity of KE and KF muscles.

The Effect of Taurine on the Recovery from Eccentric Exercise-Induced Muscle Damage in Males

Eccentric exercise is known to bring about microstructural damage to muscle, initiating an inflammatory cascade involving various reactive oxygen species. This, in turn, can significantly impair physical performance over subsequent days. Taurine, a powerful endogenous antioxidant, has previously been shown to have a beneficial effect on muscle damage markers and recovery when taken for a few days to several weeks prior to eccentric exercise. However, to date no studies have looked at the effects of supplementing over the days following eccentric exercise on performance recovery. Thus, this study aimed to determine whether supplementing with taurine over three days following eccentric exercise attenuated the rise in serum creatine kinase and improved performance recovery in males. In a blinded, randomized, crossover design, ten recreationally-fit male participants completed 60 eccentric contractions of the biceps brachii muscle at maximal effort. Following this, participants were supplemented with 0.1 g∙kg−1 body weight∙day−1 of either taurine or rice flour in capsules. Over the next three mornings participants underwent blood tests for the analysis of the muscle damage marker creatine kinase and carried out performance measures on the isokinetic dynamometer. They also continued to consume the capsules in the morning and evening. The entire protocol was repeated two weeks later on the alternate arm and supplement. Significant decreases were seen in all performance measures from pre- to 24-h post-eccentric exercise (p < 0.001) for both taurine and placebo, indicating the attainment of muscle damage. Significant treatment effects were observed only for peak eccentric torque (p < 0.05). No significant time × treatment effects were observed (all p > 0.05). Serum creatine kinase levels did not significantly differ over time for either treatments, nor between treatments (p > 0.05). These findings suggest that taurine supplementation taken twice daily for 72 h following eccentric exercise-induced muscle damage may help improve eccentric performance recovery of the biceps brachii.

Leg press exercise can reduce functional hamstring:quadriceps ratio in the elderly

The aim of this study was to investigate whether 12 weeks of leg press strength training exercise could affect the conventional and functional hamstring:quadriceps ratios in the elderly. Twelve elderly participants were submitted to a 12 week progressive training protocol (two sessions/week) using a 45° leg press exercise. A significant increase in the one repetition maximum was observed after 4, 8, and 12 weeks (p = 0.001, p < 0.001, and p < 0.001, respectively) compared to week 0 and after 8 (p = 0.011) and 12 weeks (p = 0.001) compared to week 4. The concentric knee extensor peak torque was significantly higher at weeks 8 (p = 0.001) and 12 (p = 0.024) compared to week 0. There was no change in the concentric and eccentric knee flexor peak torques (p = 0.629 and 0.274, respectively) and conventional ratio (p > 0.314) after 12 weeks of training. The functional ratio (eccentric knee flexor peak torque:concentric knee extensor peak torque) reduced significantly after 8 (p = 0.034) and 12 (p = 0.036) weeks of strength training. Although the 45° leg press exercise requires knee extensor and flexor, hip extensor, and plantar flexor muscle strength, our findings suggest that the isolated use of the 45° leg press exercise reduces the knee functional ratio after 8 weeks of training. Therefore, 45° leg press exercise alone, without a hamstring exercise, should not be recommended for elderly individuals.

Preseason isokinetic profile of knee flexors and extensors in 30 French elite professional basketball players

Basketball is an aerobic-based anaerobic contact pivot sport with a high knee injury rate. Isokinetic assessment of knee extensor and flexor muscle is currently used in elite athletes for preseason evaluation with the aim of detecting muscular imbalance and preventing orthopedic or muscular injuries. However, only few studies have described isokinetic performances in elite basketball players. The aim of this study is to describe preseason isokinetic knee extensor and flexor muscle strength profile in professional basketball players. Thirty professional basketball players underwent a preseason isokinetic examination to evaluate the knee extensor and flexor concentric peak torque at 60°.s-1 and 240°.s-1 and flexor eccentric peak torque at 30°. s-1, using a ConTrex ® dynamometer. Statistical analysis was performed with a paired Wilcoxon Signed-Rank Test. No systematic significant difference was found between dominant or non-dominant side for: knee extensor and flexor muscle strength and knee flexor/extensor strength conventional or mixed ratios. Average deficit for agonist muscle between dominant and non-dominant side was < 10% for all muscle and contraction velocity tested. Average conventional flexor/extensor ratio ranged from 60 ± 12% to 67 ± 18%. Average mixed flexor/extensor ratio was of 99 ± 19% and 104 ± 25%, respectively for dominant and non-dominant lower limb. According to the criteria used by Croisier et al. (2008) to define muscle strength imbalance, 13 of 30 players (43%) had a preseason isokinetic muscle strength imbalance, with a potential indication for a specific compensating training. Isokinetic professional basketball players profile is unclear and the presence of a muscular strength asymmetry linked to the intensive basketball practice remains controversial. Although we observed a light trend in favor of the dominant lower limb in term of strength, our study showed no statistically significant difference between the dominant and non-dominant side, but the sample size was limited. A lot of players presented a strength imbalance and had a non-isokinetic compensating training but no isokinetic control. Further studies are needed to check if a compensating training could normalize isokinetic parameters and decrease injury rate in professional basketball players, who have a frequent history of knee injury.

Effects of Mat Pilates on hip and knee isokinetic torque parameters in elderly women

This study aimed to analyze the effects of Mat Pilates on isokinetic torque of the lower limbs in elderly women. Fourteen elderly women (Age 62 ± 3 yr) participated in 12 weeks of Mat Pilates training (60-min sessions, 3 times per week). Repetitions increased every 4 weeks and the difficulty of exercises progressed from beginner to intermediate and advanced. Peak torque was assessed before (week ‐4 and week 0, considered as a control period) and after 6 and 12 weeks of a periodized Mat Pilates intervention. The results showed significant improvements (p < 0.05) in concentric and eccentric peak torque of knee flexors muscles, hip flexor and extensor muscles after 12 weeks. Mechanical work showed significant improvement (p < 0.05) for knee extensor muscles during eccentric contractions after week 12, for hip extensor muscles during concentric contractions week 12, and for flexor muscles during concentric and eccentric contractions after week 12. We conclude that the periodization of Mat Pilates induced significant improvements in multiple isokinetic torque parameters.

Changes in Isokinetic Muscle Strength in Adolescent Soccer Players after 10 Weeks of Pre-Season Training

Background:During soccer-specific movements, the strength of knee extensors and flexors is of great importance and achieving certain strength ratios between the two has been identified as an important parameter for reducing the risk of soft tissue injuries around the knee.Objective:The aim of the study was to evaluate changes in isokinetic strength of the knee flexors and extensors and their strength ratios in elite adolescent soccer players.Methods:Before and after 10 weeks of standard pre-season soccer training with progressive eccentric hamstring exercises, the players (n=18; age 17.1±0.4 years) participated in isokinetic testing to assess concentric and eccentric peak torque at 60°·s-1.Results:After 10 weeks of training, the peak eccentric torque of the non-dominant quadriceps increased (p=0.018; ω=0.24). Additionally, the average eccentric work increased in the dominant hamstrings (p=0.007; ω=0.23), dominant quadriceps (p=0.02; ω=0.31), non-dominant hamstrings (p=0.003; ω=0.25 and non-dominant quadriceps (p=0.01; ω=0.37). Lastly, the isokinetic functional ratio (eccentric hamstrings-to-concentric quadriceps) increased in favor of eccentric hamstring strength in the non-dominant limb (p=0.04; ω=0.31).Conclusion:The results of the study indicate that pre-season training induced suboptimal changes in the isokinetic strength of the knee flexors and extensors in elite adolescent soccer players. However, the lack of injuries combined with an apparent lack of preparedness explained by slow velocity isokinetic testing indicates that future research should investigate other forms of strength testing to determine soccer-specific preparedness such as isokinetic dynamometry at higher speeds (i.e.180°.s-1or 240°.s-1) and traditional weight-room testing such as 1RM tests.

The reliability and validity of a video-based method for assessing hamstring strength in football players

Background/ObjectiveEvaluating hamstring strength by isokinetic dynamometry is limited by various practical issues such as time and cost. A video-based Nordic hamstring exercise is introduced as an alternative option. The aims of this study are to evaluate 1.) the between-session reliability and 2.) concurrent validity of the testing method compared to a standardized isokinetic dynamometry. MethodsThirty male elite footballers were recruited for the study. From the Nordic hamstring exercise, the video-analysis-determined Nordic break-point angles where the participant could no longer withstand the force of the fall (eccentric mode) and the number of seconds that the player could hold at 30° forward flexion angle (isometric mode) were measured. Intra-class correlation coefficients for between-session reliability, Pearson r correlations between the current method and isokinetic dynamometry were calculated. ResultsThe reliability of the eccentric mode was moderate (ICC (2,1) = 0.82) while that of isometric mode was poor (ICC (2,1) = 0.57). The Nordic break-point angle of the eccentric mode significantly correlated with the concentric and eccentric hamstring peak torque (r = 0.48 and 0.58, p < 0.001), while the isometric was not (r = 0.02 - 0.07, p > 0.05). ConclusionThe eccentric mode of the video-based hamstring strength test was a moderately reliable and valid method to measure the eccentric hamstring strength in elite football players.

Relation between knee extensors' strength, postural stability and variability of centre of pressure displacement during gait in adult women

Background: It has been shown that variability of walking is related to fall risk similarly as postural control and muscle strength. Joint potential of this group of variables for fall risk assessment is promising, however research interested in relations between them is lacking. Objective: The aim of this study was to investigate the relation between knee extensors' strength, centre of pressure (COP) velocity during one-leg stance and variability of COP displacement during various phases of gait cycle in middle-age women. Methods: A single group of 40 healthy women (age 56 ± 4.2 years) took part in the study. For assessment of knee extensors' strength (peak torque and average work during concentric and eccentric contractions) an isokinetic dynamometer was used. Mean velocity of COP during one-leg stance in anterior-posterior (AP) and medial-lateral (ML) directions was assessed on a force plate on a rigid surface with eyes open (two 30 s trials). Variability of COP displacement was assessed for loading response, midstance, terminal stance and preswing gait cycle phases (determined by vertical ground reaction force) in AP and ML directions. It was measured by two force plates positioned in the middle of an 8 m walkway (5 trials at a self-selected speed). For statistical analysis of relationships between variables Pearson correlation was applied. Results: Our results showed significant correlations between eccentric peak torque and COP velocity in AP direction during one-leg stance, eccentric and concentric peak torque and COP variability during loading response in both ML and AP directions and during terminal stance in AP direction. Conclusion: Loading response and terminal stance seems to be more related to knee extensors' strength. Variables derived from postural stability assessment during one-leg stance are independent from variables derived from assessment of COP displacement variability during walking.

Eccentric Exercise Program Design: A Periodization Model for Rehabilitation Applications.

The applied use of eccentric muscle actions for physical rehabilitation may utilize the framework of periodization. This approach may facilitate the safe introduction of eccentric exercise and appropriate management of the workload progression. The purpose of this data-driven Hypothesis and Theory paper is to present a periodization model for isokinetic eccentric strengthening of older adults in an outpatient rehabilitation setting. Exemplar and group data are used to describe the initial eccentric exercise prescription, structured familiarization procedures, workload progression algorithm, and feasibility of the exercise regimen. Twenty-four men (61.8 ± 6.3 years of age) completed a 12-week isokinetic eccentric strengthening regimen involving the knee extensors. Feasibility and safety of the regimen was evaluated using serial visual analog scale (VAS, 0–10) values for self-reported pain, and examining changes in the magnitude of mean eccentric power as a function of movement velocity. Motor learning associated with the familiarization sessions was characterized through torque-time curve analysis. Total work was analyzed to identify relative training plateaus or diminished exercise capacity during the progressive phase of the macrocycle. Variability in the mean repetition interval decreased from 68 to 12% during the familiarization phase of the macrocycle. The mean VAS values were 2.9 ± 2.7 at the start of the regimen and 2.6 ± 2.9 following 12 weeks of eccentric strength training. During the progressive phase of the macrocycle, exercise workload increased from 70% of the estimated eccentric peak torque to 141% and total work increased by 185% during this training phase. The slope of the total work performed across the progressive phase of the macrocycle ranged from −5.5 to 29.6, with the lowest slope values occurring during microcycles 8 and 11. Also, mean power generation increased by 25% when eccentric isokinetic velocity increased from 60 to 90° s−1 while maintaining the same workload target. The periodization model used in this study for eccentric exercise familiarization and workload progression was feasible and safe to implement within an outpatient rehabilitation setting. Cyclic implementation of higher eccentric movement velocities, and the addition of active recovery periods, are featured in the proposed theoretical periodization model for isokinetic eccentric strengthening.

Strength and endurance training reduces the loss of eccentric hamstring torque observed after soccer specific fatigue

ObjectivesTo investigate the effect of two hamstring training protocols on eccentric peak torque before and after soccer specific fatigue. ParticipantsTwenty-two university male soccer players. DesignIsokinetic strength tests were performed at 60°/s pre and post fatigue, before and after 2 different training interventions. A 45-min soccer specific fatigue modified BEAST protocol (M-BEAST) was used to induce fatigue. Players were randomly assigned to a 4 week hamstrings conditioning intervention with either a maximum strength (STR) or a muscle endurance (END) emphasis. Main outcome measuresThe following parameters were evaluated: Eccentric peak torque (EccPT), angle of peak torque (APT), and angle specific torques at knee joint angles of 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80° and 90°. ResultsThere was a significant effect of the M-BEAST on the Eccentric torque angle profile before training as well as significant improvements in post-fatigue torque angle profile following the effects of both strength and muscle endurance interventions. ConclusionsForty-five minutes of simulated soccer activity leads to reduced eccentric hamstring torque at longer muscle lengths. Short-term conditioning programs (4-weeks) with either a maximum strength or a muscular endurance emphasis can equally reduce fatigue induced loss of strength over this time period.

Effects of Kinesio Taping® on knee function and pain in athletes with patellofemoral pain syndrome

ObjectiveTo compare the knee performance and pain in athletes with patellofemoral pain syndrome (PFPS) before and after applying Kinesio Tape® (KT) on vastus medialis obliquus (VMO) muscle. ParticipantsFifteen participants (10 females, five males) with unilateral PFPS were examined and compared under taped and untaped conditions. InterventionVMO of the involved leg was taped from origin to insertion, with 75% of KT's maximal length tension. Main outcome measuresMaximal eccentric and concentric peak torques of quadriceps were measured at 60 and 180°/s angular velocities by an isokinetic dynamometer. Functional performance and pain were evaluated by functional tests (step-down and bilateral squat) and visual analog scale, respectively. ResultsPaired t-test showed statistically significant increase in VMO peak torque and also repetition of step-down test and bilateral squat after using KT. Pain intensity was also decreased significantly following KT application (p < 0.05). ConclusionsKT application over VMO can decrease pain and improve the functional performance, generally and quadriceps muscle strength, particularly, in athletes with PFPS. However, more research is needed to evaluate the long-term effects of this therapeutic procedure.

Analysis of elbow muscle strength parameters in Brazilian jiu-jitsu practitioners

ABSTRACTUpper-body dynamic and isometric maximum strength are essential components for success in Brazilian jiu-jitsu (BJJ). This study was aimed at analysing strength parameters in the elbow flexor and extensor muscles of BJJ practitioners. Participants (n = 28) performed maximum isometric contractions of elbow flexors and extensors to determine peak torque (PT), rate of force development (RFD), and the torque–angle (T–A) relationship at elbow angles of 45°, 60°, 75°, 90°, 105°, and 120°. Additionally, concentric and eccentric PTs were measured at 1.04 rad·s-1. Student t-test and ANOVA were performed using α = 0.05. Elbow flexors were stronger isometrically (P < 0.001, ES = 1.23) but weaker concentrically (P < 0.05, ES = 0.54) than extensor muscles, possibly because of the extensive grip disputes and pushing of opponents in BJJ. The T–A relationship had an inverted “U”-shape. Torque differences across elbow angles were moderate (ES = 0.62) for the extensor and large (ES = 0.92) for the flexor muscles. Isometric torque was greatest for elbow angles of 105° and 75° and smallest for 45° and 120° for extensor and flexor muscles, respectively. Elbow flexors had a greater RFD than extensors, regardless of elbow angle. The present study provides comprehensive results for elbow muscle strength in BJJ practitioners.

Humeral elevation reduces the dynamic control ratio of the shoulder muscles during internal rotation.

To determine the differences in the dynamic control ratio of the glenohumeral joint rotators, during internal rotation at 20° and 60° of humeral elevation in the scapular plan. Dynamic control ratio (DCR) is defined as the ratio between eccentric action of the lateral rotators and the concentric action of the medial rotators. A cross-sectional laboratory study. Thirty asymptomatic participants (men n=14, women n=16, mean age=29.4±8.9years, BMI: 24.1±5.4) were tested. Peak torque generated by the concentric action of the MR and the eccentric action of the LR of the shoulder joint and the DCR were evaluated on the dominant arm using an isokinetic dynamometer at 20° and 60° of humeral elevation at a speed of 20°/s. There was a significant decrease in the DCR at 60° humeral elevation when compared to 20° humeral elevation (p<0.05). This decrease was due to the significant decrease in eccentric peak torques at 60° humeral elevation when compared to 20° (p<0.05). However, there was no significant difference in the concentric peak torques between 20° and 60° (p>0.05). The significant decrease in the DCR as a consequence of a decrease in the eccentric peak torque of the LR when the humerus is in a more elevated position suggests that the introduction of humeral elevation can be used as a progression for improving the eccentric action of the shoulder LR and subsequently the dynamic control of the shoulder.

Absence of Bilateral Differences in Child Baseball Players with Throwing-related Pain

The aim of this study was to assess whether side-to-side differences in morphology and function of the upper limbs in 11-12 year-old male baseball players with throwing-related pain (n=14) were more pronounced than that of age-matched healthy untrained subjects (n=16). Baseball players 1) had played baseball≥4.5 h·wk-1 for ≥ 4 years and (2) suffered from moderate-intensity (3-6 points on 10-point questionnaire scale) throwing-related pain in the shoulder or elbow in at least 2 training sessions within the past month. The range of motion (ROM), function and structure of the elbows and shoulders were assessed using goniometry, isokinetic dynamometry and ultrasonography. While the ROM and eccentric external peak torque of internal shoulder rotation were lower, the thickness of the supraspinatus tendon, the ulnar collateral ligament and articular cartilage of the humeral head were larger in baseball players than controls. There were, however, no significant side-to-side differences in any parameter in either group. In conclusion, it is unlikely that side-to-side differences in shoulder and upper limb structure and function contributed to the throwing-related pain in young baseball players, but low shoulder eccentric external peak torque and range of internal rotation may predispose to throwing-related pain.