Shoulder functional ratio in elite junior tennis players

ObjectiveTo evaluate shoulder rotation strength and compare the functional ratio between shoulders of elite junior tennis players.DesignThis cross-sectional study evaluated muscular rotation performance of 40 junior tennis players (26 male and 14 female) with an isokinetic dynamometer.Main outcome measuresStrength variables of external (ER) and internal rotators (IR) in concentric and eccentric modes were considered. For the peak torque functional ratio, the eccentric strength of the ER and the concentric strength of the IR were calculated.ResultsAll variables related to IR were significantly higher on the dominant compared to the non-dominant side in males and females (p < 0.05), but only boys exhibited this dominance effect in ER (p < 0.05 and p < 0.001). Regarding functional ratios, they were significantly lower for the dominant shoulder (p < 0.001) and below 1.00 for both groups, indicating that the eccentric strength of the ER was not greater than the concentric strength of the IR.ConclusionElite junior tennis players without shoulder injury have shoulder rotation muscle strength imbalances that alter the normal functional ratio between rotator cuff muscles. Although these differences do not seem to affect the athletic performance, detection and prevention with exercise programs at an early age are recommended.     

The effects of eccentric hamstring strength training on dynamic jumping performance and isokinetic strength parameters: a pilot study on the implications for the prevention of hamstring injuries

ObjectivesAlthough previous research shows that the hamstring length–tension relationship during eccentric contractions plays a role in hamstring injury, training methods to promote beneficial adaptations are still unclear. The purpose of this pilot study was to determine whether an eccentric hamstring specific training programme results in favourable adaptations.DesignEccentric training consisting of the Nordic hamstring exercise performed twice a week for four weeks. Pre- and post-training concentric/concentric isokinetic testing of peak torque (PT) and position of peak torque (POS) was performed for both the quadriceps and hamstrings of both legs at 60° s⁻¹. Vertical jump height was also assessed.ParticipantsNine athletic, male subjects with no previous strength training experience.ResultsThere was a significant increase in vertical jump height (pre=51.0±4.8 cm, post=54.4±6.3 cm, p=0.04), a significant reduction in quadriceps PT (pre=204.6±21.9 N.m., post=181.5±19.9 N.m., p=0.01), a significant decrease in hamstring POS from full knee extension (pre=32.5±7.4°, post=26.2±8.6°, p=0.01) and a significant hamstring POS difference between limbs (dominant=33.8±9.5°, non-dominant=24.9±6.5°, p=0.01).ConclusionNordic hamstring exercise training may produce favourable neuromuscular adaptations for the possible prevention of hamstring injuries while enhancing performance in athletic, untrained males.     

Effect of concentric and eccentric hamstring training on sprint recovery,strength and muscle architecture in inexperienced athletes

ObjectivesTo investigate whether five-weeks of concentric (CON) or eccentric (ECC) hamstring strength training have different effects on recovery from sprint running, eccentric strength and architecture of the biceps femoris long head (BF_LH).DesignCohort study.MethodsThirty males (age, 22.8 ± 4.1 y; height, 180.1 ± 6.4 cm; weight, 85.2 ± 14.6 kg) were allocated into either a CON or ECC group, both performing nine sessions of resistance training. Prior to and immediately after the five-week intervention, each participant’s BF_LH fascicle length (FL), pennation angle (PA), muscle thickness (MT), peak isometric KF torque and Nordic eccentric strength were assessed. Post-intervention, participants performed two timed sprint sessions (10 × 80 m) 48 h apart. Blood samples and passive KF torques were collected before, immediately after, 24 h and 48 h after the first sprint session.ResultsAfter five-weeks of strength-training, fascicles lengthened in the ECC (p < 0.001; d = 2.0) and shortened in the CON group (p < 0.001; d = 0.92), while PA decreased for the ECC (p = 0.001; d = 0.52) and increased in the CON group (p < 0.001; d = 1.69). Nordic eccentric strength improved in both ECC (p < 0.001; d = 1.49) and CON (p < 0.001; d = 0.95) groups. No between-group differences were observed in peak isometric strength (p = 0.480), passive KF torques (p = 0.807), sprint performance decrements between sprint sessions (p = 0.317) and creatine kinase (p = 0.818).ConclusionsDespite inducing significant differences in BF_LH muscle architecture, there were no significant between group differences in sprint performance decrements across two sprint sessions.     

Acute alcohol consumption aggravates the decline in muscle performance following strenuous eccentric exercise

This study investigated the effects of acute moderate alcohol intake on muscular performance during recovery from eccentric exercise-induced muscle damage. Eleven healthy males performed 300 maximal eccentric contractions of the quadriceps muscles of one leg on an isokinetic dynamometer. They then consumed a beverage containing 1 g/kg bodyweight ethanol (as vodka and orange juice) (ALC). On another occasion they performed an equivalent bout of eccentric exercise on the contralateral leg after which they consumed an isocaloric quantity of orange juice (OJ). Measurement of maximal isokinetic (concentric and eccentric) and isometric torque produced across the knee, plasma creatine kinase (CK) concentrations and muscle soreness were made before and at 36 and 60 h following each exercise bout. All measures of muscle performance were significantly reduced at 36 and 60 h post-exercise compared to pre-exercise measures (all p < 0.05). The greatest decreases in peak strength were observed at 36 h with losses of 12%, 28% and 19% occurring for OJ isometric, concentric, and eccentric contractions, respectively. However, peak strength loss was significantly greater in ALC with the same performance measures decreasing by 34%, 40% and 34%, respectively. Post-exercise plasma creatine kinase activity and ratings of muscle soreness were not different between conditions (both p > 0.05). These results indicate that consumption of even moderate amounts of alcohol following eccentric-based exercise magnifies the normally observed losses in dynamic and static strength. Therefore, to minimise exercise related losses in muscle function and expedite recovery, participants in sports involving eccentric muscle work should avoid alcohol-containing beverages in the post-event period.     

The effect of soft tissue release on delayed onset muscle soreness: A pilot study

ObjectivesTo examine soft tissue release (STR) as an intervention for delayed onset muscle soreness (DOMS).DesignA mixed-subjects experimental design was used. Participants performed 4 × 20 eccentric elbow extensions at 80% of 1RM. Participants received either STR (50%) or no treatment (50%). DOMS measurements were taken before the elbow extensions and at 0, 24, and 48 h afterwards.SettingThe study was conducted at the University of Essex exercise physiology laboratory.ParticipantsTwenty male participants, unaccustomed to strength conditioning, completed the study.Main outcome measuresDOMS was evaluated using relaxed joint angle (RJA), active range of motion (AROM), passive range of motion (PROM), and arm girth measurements. Soreness ratings were measured using a 100 mm visual analogue scale (VAS).ResultsIn both conditions there were post-DOMS task increases in VAS ratings (p < 0.0001) and arm girths (p < 0.0001), and decreases in RJA (p < 0.0001), AROM (p < 0.0001), and PROM (p < 0.0001). STR group VAS scores were higher immediately (p < 0.01) and 48 h after treatment (p < 0.005). There were no other between-group differences and none of the measurements returned to baseline levels by 48 h.ConclusionsSTR exacerbates the DOMS sensation yet does not seem to improve the rate of recovery during the first 48 h.     

Beetroot juice supplementation increases concentric and eccentric muscle power output. Original investigation

ObjectivesBeetroot juice (BJ) supplementation has been reported to enhance skeletal muscle contractile function; however, it is currently unclear whether BJ supplementation elicits comparable improvements in power output during different types of skeletal muscle contractions. The purpose of the current study was to assess the effect of BJ supplementation on power output during concentric (CON) and eccentric (ECC) muscle contractions during a half-squat.DesignIn a randomized, double-blind placebo-controlled crossover design, eighteen adult males (age: 22.8 ± 4.9 y) completed two experimental testing sessions 2.5 h following the acute ingestion of 140 mL nitrate-rich BJ concentrate or a placebo.MethodsEach experimental session comprised four sets of eight all-out half-squat repetitions with each set completed with a different moment intertia (0.025, 0.050, 0.075 and 0.100 kg·m^?2).ResultsCompared to placebo, BJ supplementation increased mean power output (MP) during the CON (ES: 0.61–1.01) and ECC (ES: 0.54–0.89; all p < 0.05) movement phases to a similar extent. Moreover, comparable increases in peak power output (PP) during the CON (ES: 0.86–1.24) and ECC (ES: 0.6–1.08; all p < 0.05) movement phases were observed following BJ supplementation.ConclusionAcute BJ supplementation increased mean and peak lower limb power output in the concentric and eccentric movement phases of a half-squat. These findings improve understanding of the effects of BJ supplementation on skeletal muscle contractile function and might have implications for enhancing sports performance in events where muscle power output is a key performance determinant.     

The effects of multidirectional soccer-specific fatigue on markers of hamstring injury risk

The purpose of this work was to investigate the effect of multidirectional soccer-specific fatigue on hamstring muscle strength and angle of peak torque. Sixteen male semi-professional soccer players (mean ± S.D.: age: 21.3 ± 2.9 years; height 185.0 ± 8.7 cm; body mass 81.6 ± 6.7 kg) completed the SAFT⁹⁰, a multidirectional, intermittent 90-min exercise protocol based on data from English Championship soccer matches. Prior to exercise (t₀), at half-time (t₄₅) and post-exercise (t₁₀₅), subjects performed three maximal dominant limb isokinetic contractions (Biodex, System 3) at 120° s^?1 through a 90° range for concentric and eccentric knee flexors and concentric knee extensors. Analysis of variance revealed significant time dependant reductions in gravity corrected eccentric hamstring peak torque, and consequently in the functional hamstring:quadriceps ratio (P < 0.01). Eccentric hamstring peak torque decreased significantly during each half (t₀: 272.0 ± 43.2; t₄₅: 240.4 ± 43.3; t₁₀₅: 226.3 ± 45.7 N m). The functional hamstring:quadriceps ratio also decreased significantly during each half (t₀: 116.6 ± 21.2; t₄₅: 107.1 ± 17.6; t₁₀₅: 98.8 ± 20.3%). There were no significant changes in concentric hamstring or quadriceps peak torque observed during SAFT⁹⁰ (P > 0.05). Data analysis also revealed significant differences for Angle of Peak Torque for eccentric hamstrings (P < 0.05) which was significantly higher at the end of each half (t₄₅: 37 ± 15; t₁₀₅: 38 ± 18°) than the pre-exercise value (t₀: 28 ± 12°). There was a time dependant decrease in peak eccentric hamstring torque and in the functional strength ratio which may have implications for the increased predisposition to hamstring strain injury during the latter stages of match-play.     

Kinetic comparison of older men and women during walk-to-stair descent transition

Stair walking is one of the most challenging tasks for older adults, with women reporting higher incidence of falls. The purpose of this study was to investigate the gender differences in kinetics during stair descent transition. Twenty-eight participants (12 male and 16 female; 68.5 and 69.0 years of mean age, respectively) performed stair descent from level walking in a step-over-step manner at a self-selected speed over a custom-made three-step staircase with embedded force plates. Kinematic and force data were combined using inverse dynamics to generate kinetic data for gender comparison. The top and the first step on the staircase were chosen for analysis. Women showed a higher trail leg peak hip abductor moment (−1.0 N m/kg), lower trail leg peak knee extensor moment and eccentric power (0.74 N m/kg and 3.15 W/kg), and lower peak concentric power at trail leg ankle joint (1.29 W/kg) as compared to men (p < 0.05; −0.82 N m/kg, 0.89 N m/kg, 3.83 W/kg, and 1.78 W/kg, respectively). The lead leg knee eccentric power was also lower in women (p < 0.05). This decreased ability to exert knee control during stair descent transition may predispose women to a higher risk of fall.     

Kinetic comparison of older men and women during walk-to-stair descent transition

Stair walking is one of the most challenging tasks for older adults, with women reporting higher incidence of falls. The purpose of this study was to investigate the gender differences in kinetics during stair descent transition. Twenty-eight participants (12 male and 16 female; 68.5 and 69.0 years of mean age, respectively) performed stair descent from level walking in a step-over-step manner at a self-selected speed over a custom-made three-step staircase with embedded force plates. Kinematic and force data were combined using inverse dynamics to generate kinetic data for gender comparison. The top and the first step on the staircase were chosen for analysis. Women showed a higher trail leg peak hip abductor moment (−1.0 N m/kg), lower trail leg peak knee extensor moment and eccentric power (0.74 N m/kg and 3.15 W/kg), and lower peak concentric power at trail leg ankle joint (1.29 W/kg) as compared to men (p < 0.05; −0.82 N m/kg, 0.89 N m/kg, 3.83 W/kg, and 1.78 W/kg, respectively). The lead leg knee eccentric power was also lower in women (p < 0.05). This decreased ability to exert knee control during stair descent transition may predispose women to a higher risk of fall.     

Isokinetic knee function in healthy subjects with and without Kinesio taping

ObjectiveThis study examined the difference in the isokinetic knee performance in healthy subjects with and without the Kinesio tape application onto the skin surface overlying the vastus medialis.DesignA cross-sectional experimental study.SettingClinical setting.Participants30 healthy participants.Main outcome measuresMaximal concentric knee extension and flexion at three angular velocities (60, 120 and 180°/s) were measured with an isokinetic dynamometer. Normalized peak torque, normalized total work done and time to peak torque of knee extension and flexion were compared by repeated measures ANOVA.ResultsThere was no significant main effect in ANOVA in normalized peak torque and normalized total work done between taping conditions and angular velocities. Conversely, participants demonstrated significant shorter time to peak extension torque with the tape condition (p = 0.03). Pair-wise comparisons indicated that such time reduction (36–101 ms) occurred at all three angular velocities (p < 0.01).ConclusionThis investigation demonstrated the application of Kinesio tape did not alter the muscle peak torque generation and total work done but shortened the time to generate peak torque. This finding may contribute to the rationale in injury prevention and rehabilitation in athletes with Kinesio taping.     

Changes in serum fast and slow skeletal troponin I concentration following maximal eccentric contractions

ObjectivesWe tested the hypothesis that fast skeletal muscle troponin I (fsTnI) concentration in serum would increase more than those of slow skeletal muscle troponin I (ssTnI) after eccentric exercise of the elbow flexors using a sensitive blood marker to track fibre specific muscle damage.DesignObservational comparison of response in a single experimental group.MethodsEight young men (26.4 ± 6.2 years) performed 210 (35 sets of 6) eccentric contractions of the elbow flexors on an isokinetic dynamometer with one arm. Changes in serum fsTnI and ssTnI concentrations, serum creatine kinase (CK) activity, and maximal voluntary isometric contraction torque (MVIC) before and 1, 2, 3, 4 and 14 days following exercise were analysed by a Student–Newman–Keuls multiple comparison test. The relationship between serum CK activity and fsTnI or ssTnI concentrations was determined using a Pearson's product moment correlation.ResultsSignificant (P < 0.05) decreases in MVIC and increases in serum CK activity and fsTnI were evident after exercise, but ssTnI did not change. The time course of changes in fsTnI was similar to that of CK, peaking at 4 days post-exercise, and the two were highly correlated (r = 0.8).ConclusionsIncreases in serum fsTnI concentrations reflect muscle damage, and it seems likely that only fast twitch fibres were damaged by eccentric contractions.     

Shoulder internal and external rotations torque steadiness in overhead athletes with and without impingement symptoms

ObjectivesThis study aimed to investigate torque steadiness of shoulder internal and external rotations in regularly training overhead athletes with and without impingement symptoms.DesignCross-sectional laboratory study.MethodsThree groups were evaluated: athletes with impingement symptoms (n = 21), asymptomatic athletes (n = 25) and non-athletes (n = 21). To assess torque steadiness, the participants performed 3 submaximal contractions (35% of peak torque) for 10 s each, with the arm at 90° of shoulder abduction and 90° of external rotation. The standard deviation, coefficient of variation, mean exerted torque and time to stability were measured from the steadiness trials.ResultsThe standard deviation of internal rotation was higher in asymptomatic athletes than in non-athletes (p < 0.01); however, there was no difference between the athletes with impingement symptoms and the other groups. The other variables presented no differences among the groups.ConclusionsHigher torque fluctuation of shoulder internal rotation in asymptomatic athletes may point to neuromuscular adaptations related to throwing training. However, the steadiness patterns of athletes with impingement symptoms did not differ from those of asymptomatic athletes or non-athletes.     

Correlation of isokinetic and novel hand-held dynamometry measures of knee flexion and extension strength testing

ObjectivesDescribe inter-rater reliability of, and correlations between a novel method of isometric knee extension and flexion and eccentric knee flexion strength using hand-held dynamometry and isokinetic testing for flexion/extension in the knees of athletic participants. Document strength data normalized to the individual's limb muscle mass.DesignObservational and reliability study.MethodsInter-rater reliability for each of the hand-held dynamometry measures was established in both legs of 10 volunteers (6 male). During routine annual screening, 216 male professional football (soccer) players were examined using these same measures in addition to performing an isokinetic evaluation of knee flexion and extension strength. Intra-class correlation coefficients for inter-rater reliability, Pearson r correlations between hand-held dynamometry and isokinetic dynamometry were calculated. Peak torque, peak torque normalized to: body weight; lean body mass; and lean limb mass were documented.ResultsExcellent inter-rater reliability was demonstrated with intra-class correlation_(2,1) values of 0.90, 0.91, and 0.96, for the eccentric hamstrings, isometric hamstrings, and isometric quadriceps measures respectively. Medium to high correlations (r = 0.322–0.617) which were all significant (p < 0.001) were found for the comparisons between the hand-held dynamometry and isokinetic measures.ConclusionsWe present 3 novel and reliable methods of examining knee flexion and extension strength using hand-held dynamometry which require less skill and strength on the part of the examiner than previous measures. Correlations between these measures and isokinetic dynamometry are documented. The hand-held dynamometry examinations took less than 4 min per player to conduct and may be useful in clinical practice where isokinetic examination can be difficult to implement.     

Validity of predicting left ventricular end systolic pressure changes following an acute bout of exercise

ObjectivesLeft ventricular end systolic pressure (LV ESP) is important in assessing left ventricular performance and is usually derived from prediction equations. It is unknown whether these equations are accurate at rest or following exercise in a young, healthy population.DesignMeasured LV ESP vs. LV ESP values from the prediction equations were compared at rest, 15 min and 30 min following peak aerobic exercise in 60 participants.MethodsLV ESP was obtained by applanation tonometry at rest, 15 min post and 30 min post peak cycle exercise.ResultsMeasured LV ESP was significantly lower (p < 0.05) at all time points in comparison to the two calculated values. Measured LV ESP decreased significantly from rest at both the post15 and post30 time points (p < 0.05) and changed differently in comparison to the calculated values (significant interaction; p < 0.05). The two LV ESP equations were also significantly different from each other (p < 0.05) and changed differently over time (significant interaction; p < 0.05).ConclusionsThe two commonly used prediction equations did not accurately predict either resting or post exercise LV ESP in a young, healthy population. Thus, LV ESP needs to be individually determined in young, healthy participants. Non-invasive measurement through applanation tonometry appears to allow for a more accurate determination of LV ESP.     

Hamstring strength and architectural adaptations following inertial flywheel resistance training

ObjectivesTo investigate the architectural and strength adaptations of the hamstrings following 6-weeks of inertial flywheel resistance training.DesignRandomised, stratified training interventionMethodsTwenty healthy males undertook 6-weeks of a conventional (n = 10) or eccentrically biased (n = 10) flywheel leg-curl training intervention as well as a subsequent 4-week detraining period. Biceps femoris long head (BFlh) architecture was assessed weekly, whilst assessments of eccentric and isometric knee flexor strength and rate of force development (RFD) were conducted prior to and following the intervention and detraining periods.ResultsThe participants who undertook the eccentrically biased flywheel intervention showed a significant 14 ± 5% (p < 0.001, d = 1.98) increase in BFlh fascicle length after 6-weeks of training. These improvements in fascicle length subsequently declined by 13 ± 4% (p < 0.001. d=-2.04) following the 4-week detraining period. The conventional flywheel leg-curl training group saw no changes in BFlh fascicle length after the intervention (-0.5%±0.8%, p = 0.939, d=-0.04) or detraining (-1.1%±1%, p = 0.984, d=-0.03) periods. Both groups saw no changes in any of the strength or RFD variables after the intervention or the detraining period.ConclusionsFlywheel leg-curl training performed with an eccentric bias led to significant lengthening of BFlh fascicles without a change in RFD, eccentric or isometric strength. These increases in fascicle length were lost following a 4-week detraining period. Conventional flywheel leg-curl training resulted in no changes in fascicle length, strength and RFD. These findings suggest that additional eccentric bias is required during inertial flywheel resistance training to promote fascicle lengthening in the BFlh, however this may still be insufficient to cause alterations to strength and RFD.     

Reliability of shoulder rotators isokinetic strength imbalance measured using the Biodex dynamometer

BackgroundIsokinetic assessment of shoulder internal and external rotators is commonly used by clinicians to assess muscle performance and to guide rehabilitation. The reliability of isokinetic assessment is fundamental to track small but clinically relevant changes.ObjectivesWe aimed to analyze the absolute and relative reliability of strength imbalance indices such as peak torque ratios (ERconc/IRconc, ERecc/IRecc, ERecc/IRcon, IRecc/ERcon), bilateral concentric and eccentric strength ratios, and to examine the reliability of external rotator and internal rotator peak torque measured using a Biodex^® dynamometer in the seated position.DesignCross-sectional laboratory study.MethodsForty-six healthy participants were tested twice with seven days between sessions, at 60 °/s and 120 °/s concentrically, and 30 °/s eccentrically.ResultsLow to moderate relative reliability (intraclass correlation coefficient: 0.25–0.81) was found for unilateral and bilateral strength imbalance ratios. High intraclass correlation coefficient values (0.87–0.97) were found for peak torque. Concerning absolute reliability, the standard error of measurement ranged from 9.1 to 25.6% for strength imbalance ratios and from 7.7 to 14.5% for peak torque measurements, and minimal detectable change ranged from 25.2 to 71% for strength imbalance ratios and from 21.3 to 40.2% for peak torque measurements.ConclusionsThe standard error of measurement and minimal detectable change reported in the present study should be taken into account when evaluating the individual longitudinal changes in clinical practice.     

Effects of 4-week slackline training on lower limb joint motion and muscle activation

ObjectivesTo investigate the effects of four weeks of slacklining on lower limb kinematics and muscle activity following a slip of the upright stance.DesignA randomized, gender matched study.MethodsTwenty-four young healthy adults participated in the study and were assigned to either a training or a control group. The training group completed a 4-week training program on slacklines, while the control group received no slackline training. Before and after training, participants performed single leg standing tasks on a moveable platform. During medio-lateral platform perturbation, platform displacement, lower limb joint motion (ankle, knee and hip) and surface electromyography (EMG) measurements from six lower limb muscles were recorded.ResultsIn the training group, a decrease in platform mean and maximum velocity (all p < 0.05) was detected, but no changes were observed for the release time and maximum deflection (all p > 0.05) of the platform. Regarding lower limb kinematics, a reduced corrective action was detected in the knee joint (p < 0.05), whereas only a trend towards a decrease could be observed in the ankle joint (p < 0.1). EMG data revealed an enhanced activation of the rectus femoris (p < 0.05), as well as a trend to increased rectus femoris to biceps femoris co-activation (p = 0.06) in the preparatory phase for training group.ConclusionsThe data strongly support that slacklining can improve postural control and enhance functional knee joint stability, which seems to be induced by enhanced preparatory muscle activation of the rectus femoris.     

Kinematic and electromyographic analysis in patients with patellofemoral pain syndrome during single leg triple hop test

Possible delays in pre-activation or deficiencies in the activity of the dynamic muscle stabilizers of the knee and hip joints are the most common causes of the patellofemoral pain syndrome (PFPS). The aim of the study was to compare kinematic variables and electromyographic activity of the vastus lateralis, biceps femoris, gluteus maximus and gluteus medius muscles between patients with PFPS and health subjects during the single leg triple hop test (SLTHT). This study included 14 female with PFPS (PFPS group) and 14 female healthy with no history of knee pain (Healthy group). Kinematic and EMG data ware collected through participants performed a single session of the SLTHT. The PFPS group exhibited a significant increase (p < 0.05) in the EMG activity of the biceps femoris and vastus lateralis muscles, when compared with the healthy group in pre-activity and during the stance phase. This same result was also found for the vastus lateralis muscle (p < 0.05) when analyzing the EMG activity during the eccentric phase of the stance phase. In kinematic analysis, no significant differences were found between the groups. These results indicate that biceps femoris and vastus lateralis muscles mainly during the pre-activation phase and stance phases of the SLTHT are more active in PFPS group among healthy group.     

Wearing a sports compression garment on the performance of visuomotor tracking following eccentric exercise: A pilot study

Clinical compression garments have been shown to improve functional control in patients with motor impairments, however, investigation in functional control has not been observed whilst wearing sports compression garments. This pilot study assessed motor control changes in the bicep brachii muscle following a bout of eccentric exercise designed to induce delayed onset muscle soreness for intervals up to 14 days after exercise. Eight male participants performed 35 maximal isokinetic eccentric extensions at 90° s^?1. Participants where then randomly divided into one of two groups to perform a one-dimensional elbow flexion/extension visuomotor tracking task; one group wore a sports compression garment during the task, the other acted as control (no garment). The group who wore the compression garment performed the tracking task significantly better immediately post-exercise, and at days 1, 2 and 3 post-exercise (p ≤ 0.05). Non-significant but large and moderate effects sizes (ES), in tracking, were found between the two groups on day 5 (ES = 1.3) and day 7 (ES = 0.7), respectively. Further research is necessary to elucidate these preliminary findings, however, the results suggest that the wearing of sports compression garments post-eccentric exercise has a positive effect on functional motor control.     

Do dominant and non-dominant arms respond similarly to maximal eccentric exercise of the elbow flexors?

ObjectivesTwo common models to investigate the effect of interventions on muscle damage include using two groups in which one group receives an intervention while the other acts as control, and using contralateral limbs of one group. The latter model is based on the assumption that changes in markers of muscle damage are similar between limbs, but this has not been examined systematically.DesignThis study compared changes in muscle damage markers between dominant and non-dominant arms following maximal eccentric exercise of the elbow flexors.MethodsEighteen men performed 60 maximal eccentric elbow flexions of each arm separated by 4 weeks with the order of testing between arms randomised. Maximal voluntary isometric torque, range of motion, upper arm circumference, plasma creatine kinase (CK) activity and muscle soreness before and for 7 days following exercise were compared between arms using two-way repeated measures ANOVA.ResultsNo significant differences between arms were evident for any of the markers, but significant (P < 0.05) differences between first and second bouts were evident for changes in strength, circumference and CK with smaller changes following the second bout. A poor correlation was found for the magnitude of changes in the markers between dominant and non-dominant arms, suggesting that responses to eccentric exercise were not necessarily the same between arms.ConclusionsThese results show that the order affected the responses of dominant and non-dominant arms to the eccentric exercise; however, the contralateral limb design appears to be usable if bout order is counterbalanced and randomised among participants.