Force production and reactive strength capabilities after anterior cruciate ligament reconstruction

The validity and reliability of the My Jump 2 app for measuring vertical stiffness in male college players

Background

Vertical stiffness (Kvert) can be used to evaluate sports performance and injury risk in players. The My Jump 2 smartphone application (App), is increasingly being used by researchers, coaches, and players in the competitive sports field. We aimed to analyze the reliability and concurrent validity of the My Jump 2 app for measuring Kvert in male college players.

Methods

Twenty male college players (10 soccer players, 10 basketball players; age, 20.2 ± 1.3 years old; weight, 76.4 ± 6.0 kg; height, 178.3 ± 4.7 cm) volunteered to take part in this study. Three drop jumps were performed by participants from 30 cm to 40 cm on a force platform and retested after three days. All the jumps were recorded by both the Force platform and the My Jump 2 app. Data obtained from the above two devices were compared using the paired t tests, intraclass correlation coefficient (ICC), coefficient of variation (CV), Pearson product moment correlation coefficient (r), Bland-Altman plots, and one-way regression.

Results

There was almost perfect agreement between measurement instruments for the Kvert value (ICC > 0.972, 95% CI = 0.954-0.992, P < 0.01). Almost perfect agreement was observed between evaluators (ICC > 0.989, 95% CI = 0.981-0.997, P < 0.05). Also, the My Jump 2 app showed excellent intra-rater reliability in all participants (ICC = 1.000, 95% CI = 1.000-1.000, P < 0.001). The My Jump 2 showed good variability when measuring Kvert at T1 30 cm (CV = 5.4%), T1 40 cm (CV = 6.7%), T2 30 cm (CV = 5.0%), and T2 40 cm (CV = 10.3%). The test-retest reliability of My Jump 2 was moderate to good at 30 cm (ICC = 0.708, 95% CI = 0.509-0.827); however, it was lower to moderate at 40 cm (ICC = 0.445, 95% CI = 0.222-0.625). Very large correlations were observed between the force platform and the My Jump 2 for Kvert (r > 0.9655, P < 0.001).

Conclusion

The My Jump 2 smartphone application showed excellent reliability and intra-rater consistency in measuring Kvert in male college players. While demonstrating excellent intra-rater consistency and strong agreement with force platform measurements, it showed slightly lower reliability at higher jump heights. Overall, the My Jump 2 app is a valid tool for evaluating Kvert in college players with careful consideration of its limitations, particularly at higher jump heights.

Evaluating the Reliability of MyotonPro in Assessing Muscle Properties: A Systematic Review of Diagnostic Test Accuracy

Background and Objectives: Muscle properties are critical for performance and injury risk, with changes occurring due to physical exertion, aging, and neurological conditions. The MyotonPro device offers a non-invasive method to comprehensively assess muscle biomechanical properties. This systematic review evaluates the reliability of MyotonPro across various muscles for diagnostic purposes. Materials and Methods: Following PRISMA guidelines, a comprehensive literature search was conducted in Medline (PubMed), Ovid (Med), Epistemonikos, Embase, Cochrane Library, Clinical trials.gov, and the WHO International Clinical Trials platform. Studies assessing the reliability of MyotonPro across different muscles were included. A methodological quality assessment was performed using established tools, and reviewers independently conducted data extraction. Statistical analysis involved summarizing intra-rater and inter-rater reliability measures across muscles. Results: A total of 48 studies assessing 31 muscles were included in the systematic review. The intra-rater and inter-rater reliability were consistently high for parameters such as frequency and stiffness in muscles of the lower and upper extremities, as well as other muscle groups. Despite methodological heterogeneity and limited data on specific parameters, MyotonPro demonstrated promising reliability for diagnostic purposes across diverse patient populations. Conclusions: The findings suggest the potential of MyotonPro in clinical assessments for accurate diagnosis, treatment planning, and monitoring of muscle properties. Further research is needed to address limitations and enhance the applicability of MyotonPro in clinical practice. Reliable muscle assessments are crucial for optimizing treatment outcomes and improving patient care in various healthcare settings.

Lower extremity joint stiffness of autistic adolescents during running at dual speeds

Running is one of the most common forms of physical activity for autistic adolescents. However, research examining their lower extremity dynamics is sparse. In particular, no information exists regarding lower extremity joint stiffness in autistic adolescents. This study compared knee and ankle joint stiffness during the absorption phase of running between autistic adolescents and non-autistic controls. Motion capture and ground reaction forces were recorded for 22 autistic adolescents and 17 non-autistic age, sex, and BMI matched peers who ran at self-selected and standardized (3.0 m/s) speeds. Group × speed knee and ankle joint stiffness, change in moment, and range of motion were compared using mixed-model ANOVAs. There were no group × speed interactions for any variable. Autistic adolescents presented with significant (12 % and 19 %) reduced knee and ankle joint stiffness, respectively. In addition, autistic adolescents had significant reduced changes in knee and ankle joint moments by 11 % and 21 %, respectively, compared to their non-autistic peers. Only knee joint stiffness and knee joint moments were sensitive to running speed, each significantly increasing with speed by 6 %. Current literature suggests joint stiffness is an important mechanism for stability and usage of the stretch shortening cycle (or elastic recoil); as such, it is possible that the reduced ankle plantar flexor and knee extensor stiffness found in autistic adolescents in this study could be indicative of reduced efficiency during running. As group differences existed across both speeds, autistic adolescents may benefit from therapeutic and/or educational interventions targeting efficient running mechanics.

Kinetic measurement system use in individuals following anterior cruciate ligament reconstruction: a scoping review of methodological approaches

Purpose

Our primary objectives were to (1) describe current approaches for kinetic measurements in individuals following anterior cruciate ligament reconstruction (ACLR) and (2) suggest considerations for methodological reporting. Secondarily, we explored the relationship between kinetic measurement system findings and patient-reported outcome measures (PROMs).

Methods

We followed the PRISMA extension for scoping reviews and Arksey and O’Malley’s 6-stage framework. Seven electronic databases were systematically searched from inception to June 2020. Original research papers reporting parameters measured by kinetic measurement systems in individuals at least 6-months post primary ACLR were included.

Results

In 158 included studies, 7 kinetic measurement systems (force plates, balance platforms, pressure mats, force-measuring treadmills, Wii balance boards, contact mats connected to jump systems, and single-sensor insoles) were identified 4 main movement categories (landing/jumping, standing balance, gait, and other functional tasks). Substantial heterogeneity was noted in the methods used and outcomes assessed; this review highlighted common methodological reporting gaps for essential items related to movement tasks, kinetic system features, justification and operationalization of selected outcome parameters, participant preparation, and testing protocol details. Accordingly, we suggest considerations for methodological reporting in future research. Only 6 studies included PROMs with inconsistency in the reported parameters and/or PROMs.

Conclusion

Clear and accurate reporting is vital to facilitate cross-study comparisons and improve the clinical application of kinetic measurement systems after ACLR. Based on the current evidence, we suggest methodological considerations to guide reporting in future research. Future studies are needed to examine potential correlations between kinetic parameters and PROMs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40634-021-00397-0.

Arthroscopic correction of femoroacetabular impingement improves athletic performance in male athletes

PURPOSE

To measure the changes in athletic performance in athletes treated arthroscopically for femoroacetabular impingement and compare results to a matched controlled athletic cohort, over a 1-year period.

METHODS

Male athletes scheduled for arthroscopic correction of symptomatic FAI were recruited and tested (pre-operatively and 1-year postsurgery) for measures of athletic performance which included acceleration (10-m sprint), change of direction speed (CODS), squatting depth, and reactive strength index (RSI). The FAI group was compared to a matched, healthy, control group who were tested at baseline and 1 year later with no disruption to their regular training or competition status; the prevalence of anterior groin pain during testing in either group was recorded. Hip range of motion (ROM) was also measured for both groups at baseline and at 1 year in the FAI group to look for change following intervention.

RESULTS

Prior to surgery, the FAI group were slower than the control group (p < 0.001) for acceleration (3% slower) and CODS (10% slower). At 1 year, 91% of the FAI group returned to full competition at an average time of 17 weeks, while substantial reductions in pain were also noted during acceleration (51-6%, p = 0.004), CODS (62-8%, p = 0.001), and squat test (38-8%, p = 0.003). Significant improvements were seen in the FAI group for CODS (7%, p < 0.001) and squat depth measures (6%, p = 0.004) from baseline to 1 year (significant time × group interaction effects were noted for these also). The changes in performance in the control group over time were non-significant across all of the measures (n.s.). At 1-year postsurgery, there were no statistically significant differences between the groups for any of the athletic measures. There was a significant and clinically important improvement in range of hip motion in the FAI group at 1-year postsurgery (p < 0.05).

CONCLUSION

Symptomatic FAI causes substantial reductions in athletic performance compared to healthy competitors placing these athletes at a distinct performance disadvantage. The results from the current study demonstrate that arthroscopic correction (including labral repair) in athletes with symptomatic FAI, reduces pain and restores athletic performance to a level which is comparable to healthy athletes, at 1 year.

LEVEL OF EVIDENCE

II.

Leg stiffness control during drop landing movement in individuals with mechanical and functional ankle disabilities

Purpose: Individuals with mechanical ankle instability (MAI) and functional ankle instability (FAI) present with residual movement dysfunctions after an initial lateral ankle sprain. This study investigated leg stiffness control to determine how behavioural characteristics between MAI and FAI differ during single-leg drop landing movement. Methods: Thirty individuals (10 with MAI, 10 with FAI, and 10 healthy controls) participated in this study. During single-leg drop landing movement, we estimated dimensionless leg stiffness, peak vertical force (PVF), change in the displacement of leg movement, loading rate, angular joint movement, and internal joint moment for impaired and unimpaired legs, respectively. Univariate one-way analysis of variance was used for each dependent variable across leg conditions. Results: The MAI group had lower dimensionless leg stiffness with greater change in the displacement of leg movement for the impaired leg than the FAI and control groups. Moreover, reduced leg stiffness was associated with greater hip joint flexion movement in the MAI group, whereas ankle dorsiflexion movement increased to decrease the leg stiffness in the FAI and control groups. Conclusion: These findings indicate that lower leg stiffness in the MAI group than in the FAI group may be attributed to compensatory actions to minimise reliance on their ankle movement after landing.

The relationship between leg stiffness, forces and neural control of the leg musculature during the stretch-shortening cycle is dependent on the anticipation of drop height

PURPOSE

This study aimed at investigating how prior knowledge of drop heights affects proactive and reactive motor control in drop jumps (DJ).

METHODS

In 22 subjects, the effect of knowledge of three different drop heights (20, 30, 40 cm) during DJs was evaluated in seven conditions: three different drop heights were either known, unknown or cheated (announced 40 cm, but actual drop height was 20 cm). Peak ground reaction force (F_max) to body weight (BW) ratio (F_max/BW) and electromyographic (EMG) activities of three shank and five thigh muscles were assessed 150 ms before and during ground contact (GC). Ankle, knee and hip joint kinematics were recorded in the sagittal plane.

RESULTS

Leg stiffness, proactive and reactive EMG activity of the leg muscles diminished in unknown and cheat conditions for all drop heights (7-33% and 2-26%, respectively). Antagonistic co-activation increased in unknown (3-37%). At touchdown, increased flexion in knee (~ 5.3° ± 1.9°) and hip extension (~ 2° ± 0.6°) were observed in unknown, followed by an increased angular excursion in hip (~ 2.3° ± 0.2°) and knee joints (~ 5.6° ± 0.2°) during GC (p < 0.05). Correlations between changes in activation intensities, joint kinematics, leg stiffness and F_max/BW (p < 0.05) indicate that anticipation changes the neuromechanical coupling of DJs. No dropouts were recorded.

CONCLUSION

These findings underline that anticipation influences timing and adjustment of motor responses. It is argued that proactive and reactive modulations associated with diminished activation intensities in leg extensors are functionally relevant in explaining changes in leg stiffness and subsequent decline in performance.

Reactive Strength Index and Knee Extension Strength Characteristics Are Predictive of Single-Leg Hop Performance After Anterior Cruciate Ligament Reconstruction

Birchmeier, T, Lisee, C, Geers, B, and Kuenze, C. Reactive strength index and knee extension strength characteristics are predictive of single-leg hop performance after anterior cruciate ligament reconstruction. J Strength Cond Res 33(5): 1201-1207, 2019-Single-leg hop distance is incorporated into return to sport criteria after anterior cruciate ligament reconstruction (ACLR) because of its relationship with knee extension strength; however, it may be related to other strength and plyometric characteristics. The purpose of this study was to assess the association between isometric knee extension strength and plyometric characteristics, including amortization and reactive strength index (RSI), measured during a single-leg drop vertical jump and single-leg hop performance in individuals with unilateral ACLR. Participants attended 2 testing sessions. During the first session, a biomechanical analysis using a 3D motion capture system was performed to measure RSI and amortization during a single-leg drop vertical jump for maximal height. Participants completed a single hop and a triple hop for maximal distance. During the second session, isometric knee extension strength was measured during a maximal voluntary isometric contraction. Strength characteristics included peak torque, rate of torque development (RTD), RTD 0-100 ms (RTD 100), and RTD 100-200 ms (RTD 200). Fifty-two individuals (17 men/35 women) participated. Multivariable regression models revealed jump height, peak torque, and RTD 200 explained 60.9% of the variance in normalized single-leg hop distance (p < 0.001). Reactive strength index, peak torque, RTD 200, and RTD 100 significantly explained 61.8% of the variance in normalized triple hop distance (p < 0.001). Single hop distance may indicate improved knee extension strength, whereas triple hop distance may indicate improvement in reactive strength. Training to improve RSI may improve triple hop performance and clinical outcomes in this population.

A Biomechanical Comparison Among Three Kinds of Rebound-Type Jumps in Female Collegiate Athletes

BACKGROUND

Single-legged drop jumps (SDJ), single-legged repetitive jumps (SRJ), and single-legged side hops (SSH) are often used as plyometric training and functional performance tests. Differences in the kinetics and kinematic characteristics of lower extremity joints during these jumps are unclear.

HYPOTHESIS/PURPOSE

The purpose of this study was to investigate the joint motion and mechanical work of the takeoff leg from foot contact to foot-off during SDJ, SRJ, and SSH in the sagittal and frontal planes in female athletes. It was hypothesized that the joint motion and mechanical work of the lower extremity joints during the SDJ and SRJ would be larger than the SSH in the sagittal plane, those during the SSH would be larger than the SDJ and SRJ in the frontal plane, and during SRJ would be larger than SDJ.

STUDY DESIGN

Cross-sectional study.

METHODS

Seventeen female collegiate athletes participated and performed the SDJ (0.15-m box height), and SRJ and SSH (by crossing two lines 0.3 m apart). Three-dimensional coordinate data and ground reaction forces were collected. Contact time, jump height, jump index (i.e., the jump height divided by the contact time) of the SDJ and SRJ, and the total times of the SSH were calculated. Range of motion (ROM) from touchdown to the lowest center of mass, and the positive and negative (mechanical) work from touchdown to foot-off were analyzed.

RESULTS

There were no significant differences in jump performance variables. Compared to the SSH, the SDJ and SRJ had significantly larger ankle and knee ROM and positive and negative work at the lower extremity joints, except for positive work at the hip joint, in the sagittal plane (p < 0.05). Compared to the SDJ and SRJ, the SSH had a significantly larger ankle ROM and positive work at the knee joint in the frontal plane (p < 0.05). Compared to the SDJ, the SRJ had a significantly larger ROM and negative work at each lower extremity joint in the frontal plane (p < 0.05).

CONCLUSION

Although there were no significant differences in the jump performance variables, different characteristics of the takeoff leg ROM and mechanical work were found between three kinds of rebound-type jump tests. These findings may help clinicians choose jump methods to assess lower extremity function and to design plyometric training programs in sports and clinical fields.

LEVEL OF EVIDENCE

3b.

Assessing Reactive Strength Measures in Jumping and Hopping Using the Optojump™ System

The aim of this study was to assess the concurrent validity of the Optojump™ system (Microgate, Bolzano, Italy) versus a force platform in the estimation of temporal and reactive strength measures. In two separate investigations, twenty physically active males performed double-leg and single-leg drop jumps from a box height of 0.3 m and a 10 s vertical bilateral hopping test. Contact time, flight time and total time (the sum of contact and flight time) were concurrently assessed during single and double-leg drop jumps and during hopping. Jump height, the reactive strength index and the reactive strength ratio were also calculated from contact time and flight time. Despite intraclass correlation coefficients (ICCs) for all variables being close to 1 (ICC > 0.975), a significant overestimation was found in contact time (0.005 ± 0.002 s) and underestimations in flight time (0.005 ± 0.003 s), the reactive strength index (0.04 ± 0.02 m·s-1) and the reactive strength ratio (0.07 ± 0.04). Overestimations in contact time and underestimations in flight time were attributed to the physical design of the Optojump™ system as the transmitter and receiver units were positioned 0.003 m above the floor level. The Optojump™ demonstrated excellent overall temporal validity with no differences found between systems for total time. Coaches are advised to be consistent with the instrumentation used to assess athletes, however, in the case of comparison between reactive strength values collected with the Optojump™ and values collected with a force platform, regression equations are provided.

Acceleration and Orientation Jumping Performance Differences Among Elite Professional Male Handball Players With or Without Previous ACL Reconstruction: An Inertial Sensor Unit-Based Study

BACKGROUND

Handball is one of the most challenging sports for the knee joint. Persistent biomechanical and jumping capacity alterations can be observed in athletes with an anterior cruciate ligament (ACL) injury. Commonly identified jumping biomechanical alterations have been described by the use of laboratory technologies. However, portable and easy-to-handle technologies that enable an evaluation of jumping biomechanics at the training field are lacking.

OBJECTIVE

To analyze unilateral/bilateral acceleration and orientation jumping performance differences among elite male handball athletes with or without previous ACL reconstruction via a single inertial sensor unit device.

DESIGN

Case control descriptive study.

SETTING

At the athletes' usual training court.

PARTICIPANTS

Twenty-two elite male (6 ACL-reconstructed and 16 uninjured control players) handball players were evaluated.

METHODS

The participants performed a vertical jump test battery that included a 50-cm vertical bilateral drop jump, a 20-cm vertical unilateral drop jump, and vertical unilateral countermovement jump maneuvers.

MAIN OUTCOME MEASUREMENTS

Peak 3-dimensional (X, Y, Z) acceleration (m·s(-2)), jump phase duration and 3-dimensional orientation values (°) were obtained from the inertial sensor unit device. Two-tailed t-tests and a one-way analysis of variance were performed to compare means. The P value cut-off for significance was set at P < .05.

RESULTS

The ACL-reconstructed male athletes did not show any significant (P < .05) residual jumping biomechanical deficits regarding the measured variables compared with players who had not suffered this knee injury. A dominance effect was observed among non-ACL reconstructed controls but not among their ACL-reconstructed counterparts (P < .05).

CONCLUSIONS

Elite male handball athletes with previous ACL reconstruction demonstrated a jumping biomechanical profile similar to control players, including similar jumping performance values in both bilateral and unilateral jumping maneuvers, several years after ACL reconstruction. These findings are in agreement with previous research showing full functional restoration of abilities in top-level male athletes after ACL reconstruction, rehabilitation and subsequent return to sports at the previous level.

Functional Performance Testing After Anterior Cruciate Ligament Reconstruction: A Systematic Review

Background:

When to allow an athlete to return to unrestricted sporting activity after anterior cruciate ligament (ACL) reconstruction remains controversial.

Purpose:

To report the results of functional performance testing reported in the literature for individuals at differing time points following ACL reconstruction and to examine differences between graft types.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

A systematic review of Medline, Scopus, and Cochrane Central Register of Controlled Trials was performed using PRISMA guidelines. Inclusion criteria were English-language studies that examined any functional rehabilitation test from 6 months to 2 years following ACL reconstruction. All patient-, limb-, and knee-specific demographics were extracted from included investigations. All functional rehabilitation tests were analyzed and compared when applicable.

Results:

The search term returned a total of 890 potential studies, with 88 meeting inclusion and exclusion criteria. A total of 4927 patients were included, of which 66% were male. The mean patient age was 26.5 ± 3.4 years. The predominant graft choices for reconstruction were bone–patellar tendon–bone (BPTB) autograft (59.8%) and hamstring autograft (37.9%). The most commonly reported functional tests were the hop tests. The results of these functional tests, as reported in the Limb Symmetry Index (LSI), improved with increasing time, with nearly all results greater than 90% at 1 year following primary ACL reconstruction. At 6 months postoperatively, a number of isokinetic strength measurements failed to reach 80% LSI, most commonly isokinetic knee extension testing in both BPTB and hamstring autograft groups. The knee flexion strength deficit was significantly less in the BPTB autograft group as compared with those having hamstring autograft at 1 year postoperatively, while no significant differences were found in isokinetic extension strength between the 2 groups.

Conclusion:

Hop testing was the most commonly reported functional test following ACL reconstruction. Increases in performance on functional tests were predictably seen as time increased following surgery. Those with hamstring autografts may experience increased strength deficits with knee flexion versus those having BPTB autograft. These data provide information that may assist providers in determining timing of return to unrestricted sporting activity.

No evidence hip joint angle modulates intrinsically produced stretch reflex in human hopping

Motor output in activities such as walking and hopping is suggested to be mediated neurally by purported stretch reflex augmentation of muscle output. Reflex EMG activity during these tasks has been frequently investigated in the soleus muscle; with alterations in reflex amplitude being associated with changes in hip joint angle/phase of the gait cycle. Previous work has focussed on reflex activity induced by an artificial perturbation or by induction of H-reflexes. As such, it is currently unknown if stretch reflex activity induced intrinsically (as part of the task) is modulated by changes in hip joint angle. This study investigated whether hip joint angle modulated reflex EMG 'burst' activity during a hopping task performed on a custom-built partially reclined sleigh. Ten subjects participated; EMG and kinematic data (VICON motor capture system) was collected for each hop cycle. Participants completed 5 sets of 30s of self-paced hopping in (1) hip neutral and (2) hip 60° flexion conditions. There was no difference in EMG 'burst' activity or in sagittal plane kinematics (knee/ankle) in the hopping task between the two conditions. The results indicate that during a functional task such as hopping, changes in hip angle do not alter the stretch reflex-like activity associated with landing.

The clinical utility of functional performance tests within one-year post-acl reconstruction: a systematic review

INTRODUCTION

A tear of the anterior cruciate ligament (ACL) represents a significant injury for an athlete that requires substantial time away from sport, and significant rehabilitation after reconstruction. The physical therapist is responsible to determine when a patient is capable of tolerating the physical demands of daily activities and to attempt to prevent re-injury. Physical or functional performance tests (FPTs) are one mechanism used to evaluate the athlete's physical skills and capabilities prior to returning to sports participation. The purpose of this systematic review is to critically examine the clinical utility of functional performance tests used with patients less than or equal to one year post ACL reconstruction.

METHODS

A systematic review of the relevant literature was performed using PRISMA guidelines. A total of twelve studies were included for analysis.

RESULTS

Two independent blinded reviewers then analyzed and rated the final included articles (n=12) utilizing the Newcastle-Ottawa Scale (NOS). Percent overall agreement between raters for the NOS was 88% with a fixed-marginal kappa (κ) of 0.80. Of the 12 included articles, the FPTs were utilized as an outcome measure within the study design (41.7%) or studied as a measure of function (58.3%). Among those studies that used FPTs as a "measure of function" 71.4% studied a battery of FPTs, while 28.6% studied a single test. None of the studies utilized FPTs as a measure to determine readiness to return to sport.

DISCUSSION

FPTs are being utilized with patients, less than or equal to one year post ACL reconstruction, either as an assessment of functional performance or as an outcome measure. No studies identified a FPT or test battery that has construct or predictive validity for "return to sport" in athletic population one-year post-ACL reconstruction. The identification of the critical elements within the return to sport construct may allow lower extremity performance tests to be developed or test batteries assembled to incorporate the appropriate tests to examine all of these elements deemed critical. Additionally the current FPTs should undergo content and predictive validation to assist the sports physical therapist in determining the readiness of the athlete for return to sport.

Grape extract improves antioxidant status and physical performance in elite male athletes

Excessive physical exercise overproduces reactive oxygen species. Even if elite sportsmen increase their antioxidant status by regular physical training, during the competition period, this improvement is not sufficient to limit free radical production which could be detrimental to the body. The aim of this randomized, double-blind, placebo controlled, and crossover study on 20 elite sportsmen (handball = 10, basketball = 5, sprint = 4, and volleyball = 1) during the competition period was to determine if the consumption of a grape extract (GE; Vitis vinifera L.) was able to improve the parameters related to (i) anti-oxidative status and oxidative stress and (ii) physical performance. Specific biomarkers of antioxidant capacity, oxidative stress, skeletal cell muscle damage, and other general biomarkers were determined in plasma and urine before (D0) and after one month (D30) of placebo or GE supplementation (400mg·d(-1)). Effort tests were conducted using the Optojump(®) system, which allows determining the total physical performance (EnRJ45), explosive power (RJ110), and fatigue (RJL5). The plasma ORAC value was not modified in the placebo group; however, GE increased the ORAC value compared to the placebo at D30 (14 966+/-335 vs 14 242+/-339 dµmol Teq·L(-1); p < 0.05). The plasma FRAP value was significantly reduced in the placebo group, but not in the GE group. Therefore, GE limited the reduction of FRAP compared to the placebo at D30 (1 053.7+/-31.5 vs 993.7+/-26.7 µmol Teq·L(-1); p < 0.05). Urinary isoprostane values were increased in the placebo group, but were not modified in the GE group. Consequently, GE limited the production of isoprostanes compared to the placebo at D30 (1.24+/-0.12 vs 1.26+/-0.13 ng·mg(-1) creatinine; p < 0.05). GE administration, compared to the placebo at D30, reduced the plasmatic creatine phosphokinase concentration (CPK, 695.7+/-177.0 vs 480.0+/-81.1 IU·L(-1), p = 0.1) and increased hemoglobin levels (Hb, 14.5+/-0.2 vs 14.8+/-0.2 vs g·dL(-1), p < 0.05), suggesting that GE administration might protect cell damage during exercise. The high variability between sport disciplines did not permit to observe the differences in the effort test. Analyzing each individual group, handball players increased their physical performance by 24% (p < 0.05) and explosive power by 6.4% (p = 0.1) after GE supplementation compared to the placebo. Further analyses showed that CPK and Hb were the only biomarkers correlated with the increase in performance. In conclusion, GE ameliorates the oxidative stress/antioxidant status balance in elite athletes in the competition period, and enhances performance in one category of sportsmen (handball). Our results suggest that the enhancement in performance might be caused by the protective action of GE during physical exercise. These findings encourage conducting further studies to confirm the efficacy and mechanisms of action of GE on elite and occasional athletes. Key pointsGrape extract consumption improves the oxidative stress/antioxidant status balance in sportsmen.Grape extract consumption enhances physical performance in one category of sportsmen (Handball).The performance enhancement might be caused by the protective action of grape extract during physical exercise.