Inter-limb Asymmetry Research Articles

Musculoskeletal Tissue Asymmetries Following Anterior Cruciate Ligament Reconstruction

OBJECTIVE: To compare musculoskeletal tissue asymmetries between those who had undergone ACLR and non-surgical controls, and to evaluate the influence of sex on asymmetries and perceptions of knee function in ACLR patients. DESIGN: Cross-sectional cohort analysis. METHODS: Individuals (female n=11, male n=11) with a history of ACLR and matched controls (female n=10, male n=9) completed Dual-energy X-ray Absorptiometry (DXA) scans to measure lower-body bone mineral content (BMC), Fat%, and lean mass (LM). Perceptions of knee function were captured via the International Knee Documentation Committee (IKDC) instrument and inter-limb asymmetry indices (AI%) were calculated for each DXA outcome. Surgical groups and sexes were compared using independent t-tests ( p<0.05) and Cohen’s effect sizes ( d). Additionally, Pearson’s Correlation Coefficients evaluated the association between AI% and IKDC scores. RESULTS: The ACLR group showed greater lower-body asymmetries, specifically less BMC and LM and greater Fat% in the ACLR limb ( p≤0.044; d=0.63–0.87). ACLR group sex comparisons found that females had lower IKDC scores, greater asymmetries for BMC and LM ( p≤0.027, d=0.40–0.74), and these asymmetries were negatively correlated with IKDC scores (all r≥0.755; p≤0.007) while males demonstrated no such correlations. CONCLUSIONS: Individuals with a history of ACLR had persistent musculoskeletal tissue asymmetries that favored the non-surgical leg. The asymmetries were greater in female versus male patients and were associated with lower perceptions of knee function. Thus, musculoskeletal imaging may provide complementary information to the current standard of care during ACLR rehabilitation.

Sex Differences Exist in the Relationship Between Vertical Jump Performance Biomechanical Parameters and Hamstring/Quadriceps Ratio in Adolescent U18 Track and Field Athletes

Isokinetic metrics are suggested to be related to vertical jump performance, but little is known about the possible sex differences in this relationship in adolescent track and field athletes. The aim of the study was to examine the possible sex differences in the strength of the relationship between the kinetic parameters of the vertical squat jump with arms akimbo, the countermovement jump with arms akimbo, and the countermovement jump with free arm swing with the isokinetic parameters of the knee extensor and flexor muscles (angular velocities: 60°/s and 300°/s). In total, 35 (males: 21, females: 14) U18 track and field athletes were examined. The results revealed that the Men U18 group had higher vertical jump performance, higher values in the kinetic parameters of the vertical jump tests, higher knee extensor torque, and higher knee flexor torque in the non-dominant leg compared to the Women U18 group. Significant (p < 0.05) sex differences were observed in the relationship between the isokinetic parameters and the vertical jump performance metrics, as the Women U18 athletes relied more on the knee flexor torque than Men U18 athletes, and demonstrated a stronger negative relationship between selected isokinetic metrics and the pre-stretch gain in the vertical jump tests. In conclusion, it is recommended that young female track and field athletes minimize interlimb asymmetry and improve the convention ratio in their non-dominant leg to optimize vertical jump performance.

Associations Between Inter-Limb Asymmetry in Lower Limb Strength and Jump Performance in 14–15-Year-Old Basketball Players

This study aims to (1) assess the inter-limb asymmetry in hip, knee, and ankle strength and countermovement jump (CMJ) performance among adolescent basketball players and (2) examine the relationship between inter-limb asymmetry and CMJ performance. Moreover, 30 adolescent basketball players (15 boys and 15 girls) aged 14 to 15 years participated in this study. The strength of the lower limb joints was measured using an isokinetic dynamometer at a speed of 60 degrees per second. Three maximal CMJs were performed, and the highest jump was used for the final analysis. The subjects were median-split into high-asymmetry (n = 15) and low-asymmetry (n = 15) groups based on the calculated strength asymmetry scores. The asymmetry scores were calculated using the formula: (dominant–non-dominant)/dominant* 100%. The inter-limb asymmetry data ranged from 12.2% to 21.6%. A Spearman correlation analysis showed that only the inter-limb asymmetry of the ankle plantar flexor was significantly correlated with the CMJ heights (ρ = −0.56, p = 0.001). An independent t-test revealed no significant differences in strength asymmetry between boys and girls (all p > 0.05). The low-asymmetry group demonstrated significantly greater CMJ performance compared to the high-asymmetry group (ES = 1.11, 95% CI = 0.34–1.87, p = 0.007), indicating that inter-limb asymmetry of the ankle plantar flexor has a significant negative impact on CMJ performance. Coaches should focus on enhancing both the strength and symmetry of the ankle joints to improve athletic performance and prevent injuries in sports, where jumping is a common movement.

TMG Symmetry and Kinematic Analysis of the Impact of Different Plyometric Programs on Female Athletes’ Lower-Body Muscles

Asymmetries in sports are common and can lead to various issues; however, different training programs can facilitate change. This study aimed to assess the effects of opposing plyometric programs on tensiomyography lateral symmetry (TMG LS)/inter-limb asymmetry in female athletes’ lower-body muscles, alongside kinematic and body composition parameters. Twenty female subjects from basketball, volleyball, and track and field (sprinting disciplines) were divided into two experimental groups (n = 10 each). Two six-week plyometric programs (two sessions/week) were implemented: the first program (E1) focused on eccentric exercises, depth landings, while the second (E2) emphasized concentric exercises, squat jumps. TMG assessed LS in six muscles: vastus lateralis, vastus medialis, biceps femoris, semitendinosus, gastrocnemius lateralis, and gastrocnemius medialis. A kinematic analysis of the countermovement jump (CMJ) and body composition was conducted using “Kinovea; Version 0.9.4” software and InBody 770, respectively. The results showed significant increases in LS percentages (E1—VL 9.9%, BF 18.0%, GM 10.6% and E2—BF 22.5%, p < 0.05), and a significant large effect in E1 for VL, and in E2 for BF, p < 0.01). They also showed that E1 had a significant effect on VL, and that E2 had a significant large effect on BF (p < 0.01). E1 also led to increased lean muscle mass in both legs (left: 1.88%, right: 2.74%) and decreased BMIs (−0.4, p < 0.05). Both programs improved LS, with E1 enhancing muscle mass and lower-body positioning in CMJ. We recommend future studies use varied jump tests, incorporate 3D kinematic analysis, include male subjects, and examine more muscles to enhance TMG LS analysis.

Triple Jump Performance Parameters and Inter-Limb Asymmetry in the Kinematic Parameters of the Approach Run in International and Paralympic-Level Class T46/T47 Male Athletes

Background/Objectives: The triple jump is included in the Paralympic Athletics competition. The aim of the research was to examine the relationship of the phase ratios and the inter-limb asymmetry in the spatiotemporal parameters of the approach run in Paralympic and international-level Class T46/T47 triple jumpers. Methods: Eleven Class T46/T47 male athletes were recorded during the examined competitions. Step length (SL), frequency (SF), and average velocity (ASV) for the late approach run as well as the length and the percentage distribution of each jumping phase (hop, step, jump) were measured using a panning video analysis method. The inter-limb asymmetry was estimated using the symmetry angle. Results: No significant inter-limb asymmetry was found (p > 0.05). In addition, SL, SF, and ASV were not different (p > 0.05) between the steps initiated from the ipsilateral and the contralateral leg regarding the impaired arm. However, the direction of asymmetry for SF was towards the ipsilateral leg to the impaired arm in the majority of the examined athletes. The maximum speed of the approach was correlated with the triple jump distance and the magnitude of asymmetry for AVS was correlated with the vertical take-off velocity and angle for the step. Conclusions: Since the distance of the triple jump related with the peak approach speed added the negative correlation of peak approach speed with the magnitude of the symmetry angle for SL, it is suggested to minimize the asymmetries in the step characteristics during the approach run to improve triple jump performance in Class T46/T47 jumpers.

A Single Bout of On-Ice Training Leads to Increased Interlimb Asymmetry in Competitive Youth Hockey Athletes.

Interlimb asymmetry (ILA) refers to an anatomical or physiological imbalance between contralateral limbs, which can influence neuromuscular function. Investigating the influence of neuromuscular fatigue on ILA may be critical for optimizing training programs, injury rehabilitation, and sport-specific performance. The purpose of this study was to determine if a single bout of ice hockey-specific exercise creates or exacerbates lower-limb ILA. Before and after an on-ice training session, 33 youth ice-hockey athletes (14.9 [1.7]y; 11 females) performed 3 repetitions of a maximal vertical countermovement jump (CMJ), an eccentric hamstring contraction, and maximal isometric hip adduction and abduction contractions. Force- and power-related variables were analyzed to determine limb-specific neuromuscular function. The on-ice session reduced maximal isometric hip adduction (left: 7.3% [10.3%]; right: 9.5% [9.6%]) and abduction (left: 4.9% [6.9%]; right: 5.0% [8.1%]) force, but did not impair (P ≥ .10) CMJ performance (jump height, relative peak power, braking duration, and total duration). After the on-ice session, ILA was greater for CMJ propulsive impulse (6.3% [2.9%] vs 5.1% [2.6%]), CMJ braking rate of force development (19.3% [7.6%] vs 15.2% [6.4%]), and peak isometric hip adduction force (6.7% [5.5%] vs 6.1% [4.1%]). In conclusion, hockey-specific exercise leads to increased ILA for multiple force-related metrics, which may be a compensatory mechanism to maintain bilateral task performance when fatigued.

Investigation of Dynamic Balance, Limb Asymmetry and Flexibility in Jiu-Jitsu Athletes: A Preliminary Exploratory Study

This preliminary exploratory study is the first to thoroughly examine dynamic balance, inter-limb asymmetry, and flexibility in jiu-jitsu athletes, focusing on differences by fighting style, competition level, gender, and limb dominance. A total of 25 jiu-jitsu fighters participated in this cross-sectional study, which used repeated measures to ensure the reliability of the findings. Participants underwent measurements for limb lengths and were assessed for dynamic balance using the Lower and Upper Quarter Y Balance Test (LQYBT and UQYBT) and for flexibility with the Sit and Reach Test (SR). The analysis included evaluating the reliability of these tests, as well as comparing outcomes based on gender, fighting styles, competition levels, and limb dominance. The results showed that the LQYBT and UQYBT tests were reliable (ICC=0.74–0.93). There were no significant differences in dynamic balance and flexibility between different fighting styles. No significant differences were found in balance tests between the dominant and non-dominant limbs, but there were notable inter-limb asymmetries in certain measures. This study provides preliminary insights for coaches and researchers by offering reference values for balance, flexibility, and inter-limb asymmetry in jiu-jitsu athletes. However, future research with larger sample sizes is needed to better understand the differences among subgroups in this sport.

Knee muscle strength, body composition, and balance performance of youth soccer players

BackgroundMuscle strength and balance abilities have been related to game performance injury prevention. This study aimed to (1) assess knee muscle strength performance based on intra- and inter-limb asymmetries, (2) investigate the relationships between knee muscle strength, body composition, and balance, and (3) analyze the variance in the overall stability index (OSI) explained by knee muscle strength indicators after controlling for age and body composition.MethodsThe sample included 104 young male soccer players (16.0 ± 1.6 years). Body composition, knee muscle strength, and balance ability were assessed. A paired samples t-test was used to examine differences between the preferred leg (PL) and the non-preferred leg (NPL). Pearson correlations and hierarchical multiple regression were conducted to explore the relationships between strength, body composition, and balance.ResultsNo significant inter-limb asymmetries were detected for the knee flexors (KF) and knee extensors (KE) performance. The hamstrings-to-quadriceps ratio does not suggest the existence of intra-limb asymmetries (p = 0.06). Significant and negative correlations were found between KF (r = -0.38, p ≤ 0.01) and KE (r = -0.58, p ≤ 0.01) for the PL. Concerning the NPL, KE also revealed a significant and negative relationship with balance (r = -0.30, p ≤ 0.01). Significant and positive relationships were found between bodyweight, fat-free mass, and balance. After controlling for age and body composition, knee muscle strength could explain between 13% and 30% of the variance observed in the OSI (NPL and PL, respectively).ConclusionsThe results underline knee muscle strength as an important predictor of balance. Thus, training programs targeting knee muscle strength development should be considered during the season periodization by coaches and their staff throughout the players’ developmental stages.

Reliability of single-leg maximal dynamic strength performance and inter-limb asymmetries in pre-pubertal soccer players. The influence of maturity in asymmetries

The aims of this repeated measures study were (I) to determine the reliability of single-leg squat 1RM and inter-limb asymmetries in pre-pubertal athletes, and (II) to assess associations between bilateral and/or unilateral squat 1RM performance, inter-limb asymmetries, and participants’ chronological and biological age. Thirty-one soccer players (age [mean ± standard deviation] = 8.48 ± 0.47 years; body mass = 28.32 ± 3.47 kg; body height = 121.70 ± 4.11 cm) practiced two familiarization and two experimental sessions. Bilateral and unilateral squat 1RM and asymmetries between both legs were assessed. Biological age was obtained through the age at peak height velocity (12.87 ± 0.38 years) and maturity offset (3.92 ± 0.44 years). Absolute and relative reliability and Pearson's correlations were calculated. Right and left leg 1RM and asymmetries presented good relative reliability (ICCrange = 0.84–0.85) levels, but non-acceptable absolute reliability (CV ~ 12 %). Asymmetries presented trivial to small correlations with strength (Range = 0.01–0.11). Similarly, chronological, and biological age presented small correlations with strength and asymmetries (Range = 0.01–0.22). Considering the good reliability, the bilateral and unilateral 1RM back half squat test can be considered in youth soccer players. Finally, lower-body mechanical performance and asymmetry between legs show trivial to small correlations, with maturation not affecting asymmetry in male youth soccer players. In conclusion, strength and power activities and training should be placed on younger soccer players with high asymmetry scores regardless of their stage of maturation.

Magnitude and Direction of Interlimb Asymmetry and the Association of Interlimb Asymmetry with Physical Performance in Judo Athletes with Visual Impairment.

For judo athletes with visual impairments and their coaches, understanding possible muscle adaptations can be challenging. As it is commonplace for these adaptations to include interlimb asymmetry, we analyzed the magnitude and direction of interlimb asymmetry in judo athletes with visual impairments and verified the association of this asymmetry with their unilateral physical performances. Participants were 18 elite judo athletes (10 male, 8 female) with visual impairments. These athletes performed three physical tests: countermovement jump (CMJ), medicine ball throw (MBT), and handgrip strength (HGS), while we conducted unilateral right and left side assessments using the interlimb asymmetry equation for each physical test. Our main results showed that the CMJ and MBT tests presented asymmetry values above 10%; with CMJ significantly higher than HGS (p = 0.050), and with inconsistencies across the three tests in the direction of interlimb asymmetry (k = -0.22-0.26). Unilateral CMJ (left limb) was negatively correlated with asymmetry (r = -0.51; p = 0.031), and unilateral MBT (right limb) was positively correlated with asymmetry (r = 0.52; p = 0.024). Based on these results, coaches should prioritize regular assessments of interlimb asymmetry using these specific tests. This data can guide the construction of training programs aimed at minimizing asymmetry and enhancing overall physical performance. Continuous monitoring and adjustment of training strategies based on asymmetry findings are crucial for optimizing muscle balance in judo athletes with visual impairments.

Hip and shoulder flexibility in novice rhythmic gymnasts and age-matched controls: Inter-limb asymmetry

Rhythmic gymnastics is a sport of asymmetry and lateral preferences, so the main objective of this study was to examine and compare hip and shoulder range of motion (ROM) and inter-limb asymmetry in 44 rhythmic gymnasts (RGs) and 51 age-matched non-athletes (NAs), i.e. controls. The baseline characteristics of 95 female participants, divided into two age-group categories (U8: 6–8 years, N=36; U11: 8–11 years, N=59) were established, as well as their hip (right/left hip flexion, right/left hip extension, right/left hip abduction, in °) and shoulder ROM (right/left shoulder flexion, right/left shoulder extension, in °), and asymmetry index (ASI, in %) was calculated. Significant differences between RGs and NAs were established (the exception is hip and shoulder extension in U8s, p>0.05), with greater ROM values recorded in RGs. Significant age differences were recorded among RGs in hip flexion and left hip abduction (p<0.05), in favor of U11s, and within NAs only in the case of right hip flexion (p=0.017), but in favor of U8s. The presence of asymmetries (ASI>15%), as well as its absence, is established in both RGs and NAs, but statistically significant side-to-side differences were recorded in U8 NAs (shoulder flexion, p=0.044) and U11 NAs (shoulder extension, p=0.057).

Longitudinal assessment of knee joint proprioception using weight-bearing and non-weight-bearing tests throughout rehabilitation after anterior cruciate ligament reconstruction

ObjectiveEvaluate active knee joint position sense (JPS) throughout rehabilitation after anterior cruciate ligament reconstruction (ACLR). DesignLongitudinal. SettingMotion laboratory. ParticipantsTwenty-two individuals post-ACLR and 22 activity-matched non-injured controls performed weight-bearing and non-weight-bearing knee JPS tests. The ACLR participants performed at three functional timepoints: T1, able to perform single-leg sit-to-stand; T2, able to hop maximally; T3, cleared for return to sports. Controls performed on one occasion. Main outcome measuresConstant, absolute, variable errors (CE, AE, VE) and interlimb symmetry estimates (100% signifying perfect symmetry), for 40° and 65° knee flexion target angles. ResultsFor the weight-bearing 40° condition, CE and AE of the ACLR knee significantly increased from T1 to T2 (P = 0.010) and T1 to T3 (P = 0.002). Consequently, interlimb asymmetry for AE significantly increased from T1 (AEsym% = 101.2% ± 55.4%) to T3 (AEsym% = 139.7% ± 54.8%). Compared to controls, AE for the ACLR knee was significantly smaller at T1 (P = 0.016). No other significant differences were observed. ConclusionsSmaller JPS errors at early rehabilitation while weight-bearing may have been due to heightened quadriceps activation and increased γ motor neuron sensitivity, compensating for deficient ACL mechanoreceptors. In contrast, non-weight-bearing testing did not reveal changes over time. Clinicians are advised to consider these distinctions when assessing proprioception at different rehabilitation stages.

Assessment of hip abductor and adductor muscle strength with fixed-frame dynamometry: Considerations on the use of bilateral and unilateral tasks

ObjectiveTo examine the specificities and limitations of bilateral and unilateral tasks for the assessment of hip abductor and adductor strength with a commercially-available fixed-frame dynamometer. DesignCorrelational/validity study. MethodsMaximal voluntary isometric strength of hip abductors and adductors was evaluated in 130 healthy participants using unilateral and bilateral tasks. Surface EMG activity of agonist and stabilizer muscles was concomitantly recorded in a subgroup of 15 participants. ResultsFor both muscle groups, bilateral tasks resulted in higher strength values than unilateral tasks (∼25%; p < 0.001). The correlation between left- and right-side data was higher for bilateral than unilateral tasks (p < 0.05), thereby resulting in lower interlimb asymmetries (p < 0.001). Agonist EMG activity was lower for unilateral than bilateral tasks (p < 0.01). Stabilizer EMG activity (external abdominal oblique) was higher for unilateral than bilateral tasks (p < 0.05) on the ipsilateral and contralateral side for hip abductors and adductors, respectively. ConclusionsA large (25%) and quasi-systematic bilateral facilitation of strength was observed for both hip abductors and adductors. Bilateral testing led to an underestimation of interlimb asymmetries, due to higher side equivalence than unilateral tasks. Unilateral testing resulted in lower agonist EMG activity and higher stabilizer activity than bilateral tasks, especially in weaker subjects.

Effects of External Pacing Type on the Cross-Education of Motor Skill

Cross-education (CE) is a phenomenon whereby motor training of one limb leads to improved performance in the opposite untrained limb. External pacing of a motor task can enhance CE; however, the influence of different pacing methods is poorly understood. This study explored how motor training with auditory (AP) and visual pacing (VP) impacts CE with a visuomotor force target task. Sixty-one participants performed a unimanual motor task. Participants were randomized into a visual (n = 31) or auditory (n = 30) pacing stimuli condition. The primary outcome was cumulative error scores for each hand, before and after visuomotor training. Pacing type did not yield different magnitudes of CE. However, after adjusting for baseline differences, a significant hand (trained vs. untrained) × practice side (dominant or non-dominant) interaction (p = .013, η p 2 = .106) and a group main effect (p = .036, η p 2 = .165) were observed. Visual pacing resulted in greater improvements in task performance compared to auditory pacing regardless of hand or practice side, while training the dominant limb resulting in a greater interlimb asymmetry regardless of pacing stimulus. These findings have implications for applying pacing strategies during rehabilitation from unilateral injury or neurological impairment.

Relationship between Interlimb Asymmetries and Performance Variables in Adolescent Tennis Players.

Tennis is an individual sport characterised by high-intensity action, including sprints and changes of direction (COD). However, there is a gap in the knowledge of limb asymmetries in adolescent tennis players and their association with performance. The aim of this study was to investigate the relationship between asymmetry in vertical and horizontal jump tests (CMJ and HJ) and COD with lower limb performance variables in adolescent tennis players. Forty-five adolescent tennis players (age: 13.81 ± 1.08 years; height: 167.64 ± 9.9 cm; body mass: 57.48 ± 10.94 kg; body mass index: 20.27 ± 2.18 kg/m2) performed the CMJ test (unilateral and bilateral), horizontal jumps (unilateral and bilateral), 25 m sprint, and 180° COD test. The single-leg countermovement jump showed the greatest asymmetries among the different tests (6.62 ± 9.35%). Notable negative relationships were found between CMJ asymmetry and COD asymmetry with unilateral horizontal jump variables (r = -0.30 to -0.53). In addition, CMJ asymmetry showed notable relationships with CMJR (r = 0.49) and COD180R (r = 0.29), whereas COD asymmetry showed a notable relationship with COD180L (r = 0.40). On the other hand, HJ asymmetry showed no notable relationships with any variable. The main findings of this study indicate that greater imbalances in the CMJ and COD tests are associated with a reduced capacity to perform unilateral horizontal jumps. These results suggest the incorporation of training protocols to reduce interlimb asymmetries in growing athletes to improve their performance. This practical application is important for coaches and physical trainers who aim to improve the physical performance of adolescent tennis players. Greater asymmetry results in a reduced ability to produce unilateral horizontal force.

Inter-Limb Asymmetry in Female Sepak Takraw Players: An Observational Study

This study investigated the magnitude and direction of inter-limb asymmetry in 21 professional female sepak takraw players across several task-specific tests. Five inter-limb asymmetry assessments were employed: unilateral countermovement jump (Uni-CMJ), bilateral countermovement jump (Bi-CMJ), single-leg hop (SLH), triple hop test (THOP), and isokinetic concentric peak torque of the knee flexors and extensors at 60 deg/s−1, 120 deg/s−1, and 180 deg/s−1 angular velocities. A “true” inter-limb asymmetry was only observed for Uni-CMJ jump height (16.62%) and THOP distance (6.09%). Kappa coefficients demonstrated fair agreement in the direction of asymmetry between the Uni-CMJ and Bi-CMJ tests for jump height (Kappa = 26.67), but only slight agreement for peak force (Kappa = 0.11), propulsive impulse (Kappa = −0.12), and eccentric impulse (Kappa = −0.14). Fair agreement was observed between the SLH and THOP (Kappa = 0.32). Slight to moderate agreement was found for concentric peak torque across angular velocities for the knee extensors (Kappa = 0.08 to 0.48), while fair to nearly perfect agreement was noted for the knee flexors (Kappa = 0.31 to 1). The Uni-CMJ and THOP are most sensitive to detect between-limb asymmetries in female sepak takraw players. Given the inconsistencies in asymmetry direction across tests, monitoring asymmetry direction is important for strength and conditioning.

Validity and Test–Retest Reliability of a Smartphone App for Measuring Rising Time, Velocity, Power, and Inter-Limb Asymmetry During Single-Leg Sit-to-Stand Test in Female-Trained Athletes

ABSTRACT The aim was to determine the validity and test – retest reliability of the Sit to Stand App variables (rising time, vertical velocity, and power) for measuring single-leg sit-to-stand (STS) test compared to those derived from ground reaction force data. Twenty-seven female athletes performed the single-leg STS test over three consecutive sessions simultaneously recorded with a force plate and the smartphone app. Validity was assessed with Pearson’s correlation coefficient, intra-class correlation coefficient (ICC), and percentage error. Reliability was assessed with the ICC. Almost perfect correlations (r ≥ 0.95) and excellent agreement (ICC = 0.96–0.97) between the app and force plate measures with low percentage errors (≤7.3%) were found. The app showed good-to-excellent reliability (ICC = 0.88–0.92) with no differences in inter-limb asymmetry over three sessions. The app was highly valid and reliable for measuring single-leg STS performance. Practitioners can use this app to assess lower-limb performance in female athletes.

The effect of post-match fatigue on physical performance in adolescent soccer players.

Soccer involves many physically challenging actions and engaging in such activities can induce a decline in performance due to physical fatigue which predisposes players to develop injuries. The present study aimed to examine the impact of post-match fatigue on functional performance and Inter-Limb Asymmetry Index (LSI) in adolescent soccer players. Thirty-eight adolescent male soccer players (15-18 years) completed a battery of functional performance measures (Rate of Perceived Exertion (RPE) scale, 10 m sprint, agility T-test, and Single leg hop for distance (SLHD) test). The data collection started prior to a soccer match and consisted of two testing sessions; two hours before the match, while the subsequent testing session was performed within two hours immediately following the match. The study results revealed a significant effect of post-match fatigue on change of direction abilities and SLHD (moderate effect size). However, no significant differences were observed in the 10 m sprint test and LSI (P>0.05). Functional performance measures such as agility test and SLHD test can detect physical ability changes due to post-match fatigue in adolescent soccer players. The study findings offer insightful and practical information on the importance of employing field-based functional performance measures in monitoring players' recovery following a game.

Towards a more individualised assessment of post-training fatigue in young footballers

Despite improvements in training load and fatigue monitoring, fatigue status may adversely affect intrinsic risk factors, particularly in young footballers. This study aimed to better individualise the fatigue effects of a 75-min football training session in young elite male players.Eighteen players (15.6 ± 1.7 years) completed a test battery before and after a football training session. Assessments included capillary blood samples (HCO3−, lactate, pH), subjective ratings of muscle soreness and fatigue. Functional tests included 30 m field sprint, laboratory drop jump (DJ) and horizontal force-velocity (H-FvP). The k-means method was applied to the first two dimensions of principal component analysis of changes in the H-FvP and DJ tests.Football training resulted in significant physiological changes and functional impairments, in particular an increase in interlimb asymmetry in the DJ test. No significant fatigue effect was found on the H-FvP test data. However, confirming the interest of combining the two tests, cluster analysis revealed two subgroups: In the H-FvP test, Cluster 1 decreased in V‾0 (p < 0.001) and P‾max (p < 0.01), while Cluster 2 decreased in F‾0 (p < 0.001). In the DJ test, Cluster 1 decreased in mean velocity (p < 0.01), relative mean and maximum power (p < 0.01) during push-off, while Cluster 2 decreased in relative mean push-off force (p < 0.01) and increased in interlimb asymmetry during braking (p < 0.01).This study highlights the contribution and complementarity of the H-FvP and DJ tests to improve individual screening for fatigue-related functional changes in footballers. Extrapolated values from the H-FvP test led to the identification of two subgroups with opposite fatigue profiles. One subgroup showed increased interlimb asymmetry in DJ, indicating an increased risk of injury with fatigue. These findings highlight the need for individualised fatigue assessment in young footballers.

Effect of Sex and Lateral Ankle Sprain History on Dorsiflexion Range Of Motion Asymmetry During the Weight Bearing Lunge Test.

Reduced dorsiflexion range of motion (DFROM) which is commonly seen following lateral ankle sprain (LAS) has the potential to influence lower extremity biomechanics which have been linked to increased injury risk in the female athlete. Current research on the effect of sex and LAS history on DFROM is limited. This study had three aims 1) to determine the effect of sex, leg dominance and LAS history on DFROM, 2) to determine the effect of sex and LAS history on magnitude of DFROM symmetry and 3) to examine the association of sex on direction (whether dominant or non-dominant limb had the higher DFROM) of symmetry. Cross-Sectional Study. DFROM was measured bilaterally in 105 recreational athletes all participating in multidirectional sports using the tape measurement method during the weight bearing lunge test (WBLT). A mean of three measurements was used for analysis. A 3-way mixed ANOVA was carried out to determine the interaction between sex, LAS history and leg dominance on DFROM and a 2-way ANOVA for the effect of sex and LAS history on asymmetry. A chi-square test was used to determine the association of sex and direction of asymmetry. The results indicate no significant effect of sex, LAS history, and leg dominance on DFROM (p=0.65). Main effects were significant for sex and LAS on DFROM. The mean asymmetry for all participants was reported as 12.25±14.76cm. No significant effect of sex and LAS history on magnitude of asymmetry was reported. There was a significant association of sex and direction of asymmetry (χ2(1) = 11.26, p = 0.00). Sixty-five-point two percent of males were shown to have higher DFROM of their non-dominant limb compared to 75% of females who were higher in their dominant limb. Findings from this study suggest that DFROM is affected by sex and LAS history. While females have increased DFROM compared to males, those with LAS history are more likely to have a decreased DFROM on the involved side. The results also indicate that interlimb asymmetries in DFROM are present in athletes, therefore practitioners should exercise caution when using bilateral comparisons in injury and return to play assessments. 2b.