Single-leg Landing Research Articles

The Relationship between Beighton Score and Biomechanical Risk Factors among Adolescent, Female Volleyball Players

ObjectiveTo investigate the relationship between Beighton score and biomechanical risk factors, such as knee valgus, in female, adolescent volleyball players. DesignCross-sectional study. SettingBiomechanics laboratory. Participants25 adolescent, club-level female volleyball athletes (14.5 ± 1.8 years) were tested between 9/2021 – 11/2021. Main outcome measuresParticipants were asked to perform a double-leg vertical jump (DLVJ), a single-leg squat (SLS), and a single-leg drop landing (SLDL). Peak coronal plane angles during the DLVJ, SLS, and SLDL were computed. Spearman correlations were performed to identify significant relationships between Beighton score and biomechanical variables. ResultsPeak knee valgus was found to be moderately correlated to Beighton score during the DLVJ-Land (r = 0.487, p = 0.014), SLDL (r = 0.478, p = 0.016), and SLS (r = 0.439, p = 0.028) tasks. ConclusionsOverall, adolescent volleyball players with higher Beighton scores tended to exhibit a greater peak knee valgus, suggesting that such athletes could benefit from a targeted neuromuscular training or injury prevention program.

Relationship between Cognitive Demands and Biomechanical Indicators Associated with Anterior Cruciate Ligament Injury: A Systematic Review.

Anterior cruciate ligament (ACL) injury during contact sports has a high incidence that has not been reduced despite the immense resources devoted to understanding its aetiology. A neurocognitive approach could increase knowledge of the mechanisms contributing to ACL injury enabling practitioners to address and minimise future risk. To systematically review the influence of manipulating cognitive demands during motor tasks (i.e. degree of uncertainty) on biomechanical variables associated with ACL injury risk. A systematic review was performed according to the Cochrane Handbook for Systematic Reviews of Interventions by searching the major sporting electronic databases. The search strategy included four groups of terms and was conducted by two authors independently. All studies were screened using unique inclusion criteria, with the included studies assessed for risk of bias. Twenty-five studies were identified from 2031 records and included into the review process. During the experimental conditions where cognitive demands were higher, most biomechanical indicators associated with a greater risk of ACL injury during landing and cutting tasks were significantly enhanced compared with conditions with low or no cognitive demands. An increase in task complexity through cognitive load significantly leads to changes in mechanisms associated with ACL injury during single-leg landings and cutting movements. Consequently, coaches and exercise professionals should consider inclusion of dual-task paradigms or uncertainty during injury risk assessment scenarios and injury prevention programs to help identify athletes at risk of ACL injury and reduce ACL injury frequency. This protocol was registered in the PROSPERO database ( https://www.crd.york.ac.uk/PROSPERO ) in May 2022, with the registration number CRD42022315795.

Effects of Mild Fatigue on Biomechanics of Single Leg Landing in Young Male Volleyball Players

Objective: To investigate the effects of mild fatigue on the biomechanics of the lower limbs of young male volleyball players while performing single leg landing tasks. Methods: A total of ten young male volleyball players were recruited as participants in this study. After the single leg landing was performed, we compared the performance between those with and without fatigue (post- and non-fatigue, respectively). Kinematics and kinetics were collected using instruments, and related captured data were imported into OpenSim to analyze the hip, knee, and ankle joints. Results: We found that the ankle dorsiflexion angle at initial contact was significantly decreased in the post-fatigue group compared to the non-fatigue one. Meanwhile, the peak gluteus maximus force, peak gluteus medius force, peak tibialis posterior force, and peak gastrocnemius force significantly increased. There were no significant differences in the hip and knee joint flexion angles as well as the quadriceps and biceps femoris long head forces between the two groups. Conclusions: Mild fatigue can affect the performance of single leg landing, and players need to control the lower limbs by generating a higher muscle force to cope with the instability induced by fatigue. In a fatigued state, following initial contact with the ground, a decreased ankle dorsiflexion angle necessitates an increase in gastrocnemius and tibialis posterior muscle force to maintain stance during landing.

Impact of Quadriceps Muscle Fatigue on Ankle Joint Compensation Strategies During Single-Leg Vertical Jump Landing.

This study investigates the impact of quadriceps fatigue on lower limb biomechanics during the landing phase of a single-leg vertical jump (SLJ) in 25 amateur male basketball players from Ningbo University. Fatigue was induced through single-leg knee flexion and extension exercises until task failure. Kinematic and dynamic data were collected pre-fatigue (PRF) and post-fatigue (POF) using the Vicon motion capture system and the AMTI force platform and analyzed using an OpenSim musculoskeletal model. Paired sample t-tests revealed significant changes in knee and hip biomechanics under different fatigue conditions, with knee joint angle (p < 0.001), velocity (p = 0.006), moment (p = 0.006), and power (p = 0.036) showing significant alterations. Hip joint angle (p = 0.002), moment (p = 0.033), and power (p < 0.001) also exhibited significant changes. Muscle activation and joint power were significantly higher in the POF condition, while joint stiffness was lower. These findings suggest that quadriceps fatigue leads to biomechanical adjustments in the knee and hip joints, which may increase the risk of injury despite aiding in landing stability.

Can athletic footwear design features reduce anterior cruciate ligament forces during single-leg landing in young females?

Can athletic footwear design features reduce anterior cruciate ligament forces during single-leg landing in young females?

ACL injury characteristics in badminton : A registry study with prospectively collected data on sports related epidemiology and injury mechanism of 539 badminton players

BackgroundOver recent years, more anterior cruciate ligament (ACL) ruptures in badminton players have occurred. Little is known about the injury mechanism in badminton. The hypothesis is that most ACL injuries occur with single leg landings on the non-dominant leg in the backhand side or with lunge movements in the forehand side on the dominant leg. To inform prevention strategies the aim of this study was to investigate the mechanism of ACL injuries in badminton, specifically if ACL injuries occur in certain positions on the badminton court and/or with certain movements. Secondary aims were to investigate differences among gender, age groups and between recreational and tournament players. MethodsThe study, ACL Denmark, investigate ACL ruptures in a cohort of 90.610 participants diagnosed between 2000 and 2018. Of those, 539 participants reported ACL rupture during badminton and filled in an online questionnaire in December 2021–January 2022 on the injury mechanism and other injury characteristics. Data is presented as numbers, percentage, means (SD) and median (IQR) with chi square test or Fischers exact test for dichotomous outcomes. ResultsMost participants played badminton (n = 435, 81 %) as primary sport and 155 (29 %) reported to play on a competitive level (Tegner score 8). The rear court (n = 285, 40 %) was the most frequent location of injury but with a high percentage on the front and midcourt (n = 154, 22 %). The rear court was more prevalent among players aged 18–29 (p < 0.001). The most prevalent movement preceding the ACL injury was the scissor kick jump on the rear court (100, 19 %) followed by lunge at the net (70, 13 %) and lunge at the rear court (69, 13 %). One hundred and six players (15 %) were injured preceded by a deceptive shot from the opponent. The dominant leg was mainly injured in the forehand side and the non-dominant leg mainly in the backhand side. ConclusionThe most prevalent movement preceding the ACL injury was the lunge followed by the scissor kick jump. The rear court was the primary location of ACL injury in badminton and the dominant knee has a higher risk of injury in the forehand side and the non-dominant knee in the backhand side. More focus on the technical performance of lunge and scissor kick jumps and development of a badminton specific ACL injury prevention program is needed in badminton.

Unilateral Plyometric Jump Training Shows Significantly More Effective than Bilateral Training in Improving Both Time to Stabilization and Peak Landing Force in Single-Leg Lend and Hold Test: A Randomized Multi-Arm Study Conducted Among Young Male Basketball Players.

Enhancing peak landing forces and ensuring faster stabilization in the lower limbs during jumping activities can significantly improve performance and decrease the risk of injury among basketball players. This study aimed to compare the effects of unilateral (uPJT) and bilateral plyometric jump training (bPJT) programs on various performance measures, including countermovement jump (CMJ), squat jump (SJ), and single-leg land and hold (SLLH) test outcomes, assessed using force plates. A randomized multi-arm study design was employed, comprising two experimental groups (n = 25; uPJT and n = 25; bPJT) and one control group (n = 25), conducted with youth male regional-level basketball players (16.3 ± 0.6 years old). Participants underwent assessment twice, both before and after an 8-week intervention training period. The uPJT program exclusively involved plyometric drills (e.g., vertical jump exercises; horizontal jump exercises) focusing on single-leg exercises, whereas the bPJT program utilized drills involving both legs simultaneously. The outcomes analyzed included CMJ peak landing force, CMJ peak power, SJ peak force, SJ maximum negative displacement, SLLH time to stabilization, and SLLH peak landing force. The control group exhibited significantly greater SLLH time to stabilization compared to both the uPJT (p < 0.001) and bPJT (p < 0.030) groups. Additionally, time to stabilization was also significantly higher in bPJT than in uPJT (p = 0.042). Comparisons between groups in regards SLLH peak landing force after intervention revealed that the value was significantly smaller in uPJT than in bPJT (p = 0.043) and control (p < 0.001). In the remaining outcomes of CMJ and SJ, both uPJT and bPJT showed significant improvement compared to the control group (p > 0.05), although there was no significant difference between them. In conclusion, our study suggests that utilizing uPJT is equally effective as bPJT in enhancing performance in bilateral jump tests. However, it significantly outperforms bPJT in improving time to stabilization and peak landing forces during single-leg land and hold test. uPJT could be advantageous not for maximizing performance but also for potentially decreasing injury risk by enhancing control and balance during single-leg actions, which are common in basketball.

Anodal tDCS improves the effect of neuromuscular training on the feedforward activity of lower extremity muscles in female taekwondo athletes with dynamic knee valgus

Transcranial direct current stimulation (tDCS) can increase cortical excitability of a targeted brain area. This study aimed to investigate the effect of adding anodal-tDCS (a-tDCS) to neuromuscular training (NMT) on the dynamic knee valgus (DKV) and feedforward activity (FFA) of knee muscles. Thirty-four Taekwondo athletes with DKV, were randomly assigned to either NMT + a-tDCS (N = 17) or NMT + sham tDCS (N = 17). DKV and the knee muscles' FFA at the moment of single and double-leg landing and lateral hopping tasks were evaluated before and after the interventions. DKV and FFA of the knee muscles was improved in all tasks (P < 0.05), however, between-group differences were not significant (P > 0.05). The FFA of the semitendinosus, vastus medialis, gluteus medius, and gastrocnemius muscles in the single-leg landing (P < 0.05), the gluteus medius, gluteus maximus, semitendinosus, biceps femoris, and gastrocnemius muscles in the double-leg landing (P < 0.05), and the gluteus medius, gluteus maximus, and gastrocnemius muscles in the lateral hopping (P < 0.05) tasks were significantly different between the groups. A-tDCS achieved significantly larger improvements in the feedforward activity of lower extremity muscles compared with sham-tDCS. However, between-group comparisons did not show a significant difference in DKV.

Reliability and validity of knee valgus angle calculation at single-leg drop landing by posture estimation using machine learning

BackgroundThe consensus on anterior cruciate ligament (ACL) injury prevention involves the suppression of dynamic knee valgus (DKV). The gold standard for evaluating the DKV includes three-dimensional motion analysis systems; however, these are expensive and cannot be used to evaluate all athletes. Markerless motion-capture systems and joint angle calculations using posture estimation have been reported. However, there have been no reports on the reliability and validity of DKV calculations using posture estimation. Research questionThis study aimed to clarify the reliability and validity of DKV calculation using posture estimation. MethodsFifteen participants performed 10 single-leg jump landings from a height of 20 cm, and the knee joint angle was calculated using joint points measured using machine learning (MediaPipe Pose) and motion-capture systems (VICON MX). Two types of angle calculation methods were used: absolute value and change from the initial ground contact (IC). Intra- and inter-rater reliabilities were examined using intraclass correlation coefficients, and concurrent validity was examined using Pearson's correlation coefficients. To examine intra-examiner reliability, we performed single-leg jump landings at intervals of ≥3 days. ResultsThe calculation by MediaPipe Pose was significantly higher than that by the 3-D motion analysis systems (p < 0.05, error range 18.83–19.68°), and there was no main effect of knee valgus angle or time on the excursion angle from IC (p > 0.05). No significant concurrent validity was found in the absolute value, which was significantly correlated with the change in IC. Although the inter-rater reliability of the absolute value was low, the change in IC showed good reliability and concurrent validity. SignificanceThe results of this research suggest that the DKV calculation by pose estimation using machine learning is practical, with normalization by the angle at IC.

Effects of attentional focus strategies in drop landing biomechanics of individuals with unilateral functional ankle instability.

Functional Ankle Instability (FAI) is a pervasive condition that can emerge following inadequate management of lateral ankle sprains. It is hallmarked by chronic joint instability and a subsequent deterioration in physical performance. The modulation of motor patterns through attentional focus is a well-established concept in the realm of motor learning and performance optimization. However, the precise manner in which attentional focus can rehabilitate or refine movement patterns in individuals with FAI remains to be fully elucidated. The primary aim of this study was to evaluate the impact of attentional focus strategies on the biomechanics of single-leg drop landing movements among individuals with FAI. Eighteen males with unilateral FAI were recruited. Kinematic and kinetic data were collected using an infrared three-dimensional motion capture system and force plates. Participants performed single-leg drop landing tasks under no focus (baseline), internal focus (IF), and external focus (EF) conditions. Biomechanical characteristics, including joint angles, ground reaction forces, and leg stiffness, were assessed. A 2 × 3 [side (unstable and stable) × focus (baseline, IF, and EF)] Repeated Measures Analysis of Variance (RM-ANOVA) analyzed the effects of attentional focus on biomechanical variables in individuals with FAI. No significant interaction effects were observed in this study. At peak vertical ground reaction force (vGRF), the knee flexion angle was significantly influenced by attentional focus, with a markedly greater angle under EF compared to IF (p < 0.001). Additionally, at peak vGRF, the ankle joint plantarflexion angle was significantly smaller with EF than with IF (p < 0.001). Significant main effects of focus were found for peak vGRF and the time to reach peak vGRF, with higher peak vGRF values observed under baseline and IF conditions compared to EF (p < 0.001). Participants reached peak vGRF more quickly under IF (p < 0.001). Leg Stiffness (kleg) was significantly higher under IF compared to EF (p = 0.001). IF enhances joint stability in FAI, whereas EF promotes a conservative landing strategy with increased knee flexion, dispersing impact and minimizing joint stress. Integrating these strategies into FAI rehabilitation programs can optimize lower limb biomechanics and reduce the risk of reinjury.

Robust fatigue markers obtained from muscle synergy analysis.

This study aimed to utilize the nonnegative matrix factorization (NNMF) algorithm for muscle synergy analysis, extracting synergy structures and muscle weightings and mining biomarkers reflecting changes in muscle fatigue from these synergy structures. A leg press exercise to induce fatigue was performed by 11 participants. Surface electromyography (sEMG) data from seven muscles, electrocardiography (ECG) data, Borg CR-10 scale scores, and the z-axis acceleration of the weight block were simultaneously collected. Three indices were derived from the synergy structures: activation phase difference, coactivation area, and coactivation time. The indicators were further validated for single-leg landing. Differences in heart rate (HR) and heart rate variability (HRV) were observed across different fatigue levels, with varying degrees of disparity. The median frequency (MDF) exhibited a consistent decline in the primary working muscle groups. Significant differences were noted in activation phase difference, coactivation area, and coactivation time before and after fatigue onset. Moreover, a significant correlation was found between the activation phase difference and the coactivation area with fatigue intensity. The further application of single-leg landing demonstrated the effectiveness of the coactivation area. These indices can serve as biomarkers reflecting simultaneous alterations in the central nervous system and muscle activity post-exertion.

Adaptive Adjustments in Lower Limb Muscle Coordination during Single-Leg Landing Tasks in Latin Dancers.

Previous research has primarily focused on evaluating the activity of individual muscles in dancers, often neglecting their synergistic interactions. Investigating the differences in lower limb muscle synergy during landing between dancers and healthy controls will contribute to a comprehensive understanding of their neuromuscular control patterns. This study enrolled 22 Latin dancers and 22 healthy participants, who performed a task involving landing from a 30 cm high platform. The data were collected using Vicon systems, force plates, and electromyography (EMG). The processed EMG data were subjected to non-negative matrix factorization (NNMF) for decomposition, followed by classification using K-means clustering algorithm and Pearson correlation coefficients. Three synergies were extracted for both Latin dancers and healthy participants. Synergy 1 showed increased contributions from the tibialis anterior (p < 0.001) and medial gastrocnemius (p = 0.024) in Latin dancers compared to healthy participants. Synergy 3 highlighted significantly greater contributions from the vastus lateralis in healthy participants compared to Latin dancers (p = 0.039). This study demonstrates that Latin dancers exhibit muscle synergies similar to those observed in healthy controls, revealing specific adjustments in the tibialis anterior and medial gastrocnemius muscles among dancers. This research illustrates how dancers optimize control strategies during landing tasks, offering a novel perspective for comprehensively understanding dancers' neuromuscular control patterns.

The effects of core muscle fatigue on lower limbs and trunk during single-leg drop landing: A comparison between recreational runners with and without dynamic knee valgus

BackgroundA deficit in neuromuscular trunk control can impact the lower limb motion, predisposing runners to injuries. This deficit may show a greater impact on runners with dynamic knee valgus. This study aimed to compare the effect of core fatigue on kinetic, kinematic, and electromyographic parameters of the trunk and lower limbs during single-leg drop landing between runners with and without dynamic knee valgus. MethodsTwenty-seven recreational runners were allocated to the valgus (n = 14) and non-valgus groups (n = 13). They performed the test before and after a fatigue protocol, taking a step forward and landing on the force platform while maintaining balance. The fatigue protocol included isometric and dynamic exercises performed consecutively until voluntary exhaustion. The vertical ground reaction force, the sagittal and frontal plane angles, and the electromyographic activity were evaluated. The integral of electromyographic activity was calculated into three movement phases. ANOVA with repeated measures was used to verify the group, time, and interaction effects. ResultsAfter fatigue, both groups showed a significant reduction in the minimum (p = 0.01) and maximum (p = 0.02) knee angles in the frontal plane (more dynamic knee valgus) and greater gluteus medius activity (p = 0.05) from the peak of knee flexion to the end of the movement. The valgus group had a greater hip excursion (p = 0.01) and vertical linear shoulder displacement (p = 0.02) than the non-valgus. ConclusionOur results suggest that core fatigue can impact the local muscle and the distal joint and that the groups presented different strategies to deal with the demand during landing.

Neuromuscular fatigue and cognitive constraints independently modify lower extremity landing biomechanics in healthy and chronic ankle instability individuals

ABSTRACT The purpose was to determine the impact of both cognitive constraint and neuromuscular fatigue on landing biomechanics in healthy and chronic ankle instability (CAI) participants. Twenty-three male volunteers (13 Control and 10 CAI) performed a single-leg landing task before and immediately after a fatiguing exercise with and without cognitive constraints. Ground Reaction Force (GRF) and Time to Stabilization (TTS) were determined at landing in vertical, anteroposterior (ap) and mediolateral (ml) axes using a force plate. Three-dimensional movements of the hip, knee and ankle were recorded during landing using a motion capture system. Exercise-induced fatigue decreased ankle plantar flexion and inversion and increased knee flexion. Neuromuscular fatigue decreased vertical GRF and increased ml GRF and ap TTS. Cognitive constraint decreased ankle internal rotation and increased knee and hip flexion during the flight phase of landing. Cognitive constraint increased ml GRF and TTS in all three axes. No interaction between factors (group, fatigue, cognitive) were observed. Fatigue and cognitive constraint induced greater knee and hip flexion, revealing higher proximal control during landing. Ankle kinematic suggests a protective strategy in response to fatigue and cognitive constraints. Finally, these two constraints impair dynamic stability that could increase the risk of ankle sprain.

Comparison of hip abductors’ strength and 2D frontal plane projection angle during two functional tests, in females with and without patellofemoral pain

IntroductionHip abductors eccentrically maintain leg alignment during weight-bearing exercises. Hip abductors' weakness may be a significant aspect to take into account in the conservative management of Patellofemoral Pain (PFP). The aim of the study was to compare hip abductors’ eccentric strength and hip kinematics during two functional tests, in female subjects with PFP. MethodIn a cross-sectional study using convenience sampling, isokinetic Isokinetic unilateral eccentric hip abductors’ mean peak moment (MPM) at 60°/sec and Frontal Plane Projection Angle (FPPA) during Single-Leg Squat (SLS) and Single-Leg Landing (SLL) tests, were assessed in 17 asymptomatic individuals and 19 PFP patients. ResultsThe FPPA during SLL (p = 0.771) and SLS (p = 0.587), as well as the isokinetic values of the eccentric adductors' MPM at 60°/sec (p = 0.769), did not differ between the groups. The isokinetic values and the SLL (r = −0.009 to p = 0.970) and SLS (r = −0.002 to p = 0.993) in the PFP group and the control group (SLS r = 0.160 to p = 0.540) did not show any statistically significant relationships. ConclusionPFP and asymmetry in hip abduction strength are not substantially correlated. It is necessary to conduct more research to comprehend how these impairments interact and to find out if there are patient subgroups with PFP.

The effect of surface on knee landing mechanics and muscle activity during a single-leg landing task in recreationally active females

ObjectiveInvestigate the effect of surface on frontal plane knee angle, knee moment and muscle activity. DesignRandomised cross over. SettingUniversity Laboratory. MethodsTwenty females performed single-leg hop-landings onto sand, grass and firm surfaces. Kinematic, kinetic and muscle activity data were obtained. Compatibility curves were used to visualise parameter estimates alongside P- values, and S-value transforms. ResultsKnee angle for firm-sand (mean difference (d)‾ = −2.2°; 95% compatibility interval (CI): −4.6 to 0.28, p = 0.083, s = 3.6) and firm-grass (d‾ = −1.9; 95% CI: −4.3 to 0.5, p = 0.125, S = 3) yielded <4 bits of reputational information against the null hypothesis (H). 5 bits (p = 0.025) of information against H were observed for knee moment between firm-sand (d‾ = 0.17 N m/kg-1. m-1; 95% CI: 0.02 to 0.31) with similar effects for firm-grass (d‾ = 0.14 N m/kg-1. m-1; 95% CI: −0.02 to 0.29, p = 0.055, S = 4). Muscle activity across surfaces ranged from almost no (S = 1) reputational evidence against H (Quadriceps and Hamstrings) to 10–13 ‘bits’ against H for lateral gastrocnemius (lower on sand). ConclusionsOur study provides valuable information for practitioners of the observed effect sizes for lower-limb landing mechanics across surfaces in asymptomatic females.

Strength and clinical test combinations enhance predictions of sagittal and frontal plane biomechanics in single-leg landing

ObjectivesTo determine whether clinical screening tests can predict lower limb joint kinematics and kinetics outcomes eliciting anterior cruciate ligament (ACL) injury risk in single-leg landings. DesignCross-sectional study. SettingLaboratory research. ParticipantsTwenty-six professional male futsal athletes. Main outcome measuresParticipants completed the Modified Star Excursion Balance Test (mSEBT), Lateral Step Down (LSD), Lunge, Hop tests, and isometric strength tests for clinical screening of lower extremity injury risk and performed single-leg landings to assess lower extremity 3D kinematics and kinetics outcomes. ResultsmSEBT, LSD, and isometric strength were the more important tests when constructing the prediction models. The predictive power of clinical tests for screening injury risk significantly increases when combined with strength measurements (p = 0.005, f2 = 0.595). We discerned 11 biomechanical predictions, six explicitly related to the sagittal plane's biomechanics. Some predictions were leg-dependent, with muscle strength tests predominantly predicting biomechanical outcomes of the preferred leg. ConclusionCombining clinical screening tests with strength measures enhances ACL injury risk factors prediction during single-leg landings. Clustering at least two tests improves prediction accuracy, aiding injury prevention planning and decision-making.

Effects of Anterior Cruciate Ligament Reconstruction on Lower Limb Joint Angle and Shock Absorption Pattern of Adult Males during Single-Leg Drop Landing

PURPOSE This study analyzed the difference in lower extremity joint angle and shock absorption patterns at the point of maximum ground reaction force during single-leg drop landing with or without anterior cruciate ligament reconstruction (ACLR).METHODS Forty adult males were recruited for this study, with 19 in the ACLR group (age: 20.52±1.43years, height: 179.26±5.18cm, weight: 74.91±6.29kg) and 21 in the control group (age: 21.42±1.61years, height: 174.97±6.83cm, weight: 69.27±7.56kg). Participants performed single-leg landings on a 30cm tall box. An independent sample t-test was used to analyze the difference in kinetics variables at the point of maximum ground reaction force upon landing, with significance set at &lt;i&gt;p&lt;/i&gt;=0.05.RESULTS The lower limb joint angle showed significant differences in hip flexion, hip abduction, knee flexion, and knee valgus (&lt;i&gt;p&lt;/i&gt;&lt;0.05) between groups. There was no significant difference between the groups in terms of the results of kinetics variables during single-leg landing (maximum ground reaction force, lower extremity stiffness, and shock absorption time).CONCLUSIONS The ACLR group showed a clear difference in kinematics compared to the control group, but no significant difference in kinetic results was found. The two groups compensated for the same impact with different movements, though movements in the ACLR group may increase the risk of ACL re-injury. Those with ACLR should strive to reduce the risk of re-injury by training to use correct movements.

Influence of lower limb joint motion on shock attenuation during Single-Leg Landing

Influence of lower limb joint motion on shock attenuation during Single-Leg Landing

Postural Control During Single-Leg Landing in Female Athletes After Anterior Cruciate Ligament Reconstruction.

Secondary anterior cruciate ligament (ACL) injury is a complication of ACL reconstruction (ACLR), which may result from altered neuromuscular control affecting anticipatory postural adjustments (APAs) and compensatory postural adjustments (CPAs) required for maintaining balance during movement. However, it remains unclear how APAs and CPAs differ in single-leg landings post-ACLR compared to healthy subjects. The purpose of this study was to clarify the differences in muscle activities of APAs and CPAs, lower limb kinematics, and kinetics between athletes with a history of ACLR and healthy athletes during single-leg landing. Cross-sectional study. Eighteen female athletes were recruited and divided into ACLR (n = 9) and control groups (n = 9). The experimental task involved a single-leg landing from a 30 cm box. Joint angles and moments were determined using a 3-dimensional motion analysis system, while muscle activity was assessed using surface electromyography. Analysis intervals were divided into two phases: the APA phase (-150 ms to 50 ms) and the CPA phase (50 ms to 250 ms), with initial contact (0 ms) as the reference point. Muscle activity onset time was defined as the time when the baseline exceeded by the sum of mean values and 2 standard deviations. No significant differences were observed in muscle activity or onset time between the ACLR and control groups. However, an increased hip external rotation moment was observed during the CPA phase in the ACLR group. These findings suggest that APAs and CPAs of athletes who returned to sports more than 1 year post-ACLR may be similar. The increased hip external rotation moment in the ACLR group during the CPA phase could represent a specific compensatory strategy to decrease the hip internal rotation angle post-ACLR. III.