ECSS Paris 2023: OP-BM03
INTRODUCTION: A substantial proportion of anterior cruciate ligament (ACL) injuries occur in football during defensive actions involving change-of-direction (COD). Recent research has highlighted the role of cognitive demands in this movement type [1]. While previous studies have mainly focused on simple decision-making tasks using artificial stimuli (e.g., light signals), the influence of more complex and ecologically valid conditions remain largely unexplored. Thus, this study aimed (i) to determine the effects of increasing cognitive demands on biomechanical parameters during COD tasks in females and (ii) to examine the moderating role of football expertise. METHODS: Biomechanical data were obtained from 15 female participants with high football expertise (age = 22.9 ± 3.8 yrs, 14.7 ± 3.8 yrs expertise) and 14 female participants with < 1 year football expertise (age = 22.5 ± 1.8 yrs). Participants performed an approach run at 4.0 ± 0.3 m/s, followed by 90° CODs to the left or the right in response to a real opponent, who determined the direction by kicking a ball. Participants performed CODs under four conditions with increasing cognitive demand: (i) anticipated, only one option, (ii) unanticipated, two options, i.e. left or right, (iii) unanticipated, three options including a stop, and (iv) unanticipated, four options including a stop or a feint of the opponent. Knee joint mechanics, trunk and pelvis kinematics were recorded using 3D-motion analysis. A mixed 2x4 ANOVA was performed to analyze the effects of the factors expertise (between-subjects) and cognitive condition (within-subjects) on biomechanical outcomes. RESULTS: No significant main effects were observed for maximum knee abduction moment and knee abduction angle as well as knee flexion angle at initial contact (IC). However, significant condition effects were observed at IC for trunk rotation (p<0.001, d=0.54) and pelvis kinematics in frontal (p=0.004, d=0.42) and transverse planes (p=0.006, d=0.40). Post-hoc analyses revealed significantly less trunk rotation towards the cutting leg in all cognitive conditions compared to the anticipated condition. The pelvis was significantly more tilted and rotated to the contralateral leg in the anticipated condition compared to condition (iv). No effects of the factor expertise were observed. No significant effects were found for the control variables approach speed and available time to react. CONCLUSION: This study revealed that increasing cognitive demands significantly influenced trunk and pelvis kinematics but not knee joint mechanics during CODs in both high- and low expertise female football players. Given the established link between altered trunk and pelvis mechanics and ACL injury risk [2], our findings imply that whole-body kinematics, especially in CODs with increased cognitive demands, should be considered in ACL injury risk evaluations. REFERENCES: [1] Gokeler et al., J Athl Train, 2024 [2] Alentorn-Geli et al., KSSTA, 2009
Read CV Clara EbnerECSS Paris 2023: OP-BM03
INTRODUCTION: A lateral ankle sprain (LAS) typically involves trauma to the anterior talofibular ligament (ATFL). Ex vivo, ATFL has a relatively low yield and ultimate force response (1) so understanding its capacity to tolerate mechanical loading in vivo may be beneficial for injury prevention and rehabilitation. The aim of this study was to assess ATFL strain and changes in its elastic material property to passive ankle inversion rotations in participants with a history of LAS and healthy-matched controls. METHODS: Bilateral ATFLs were imaged in 34 young adults: 17 with a previous unilateral LAS (12f/5m, 25±6 years) and 17 healthy-matched controls (12f/5m, 25±6 years) using a custom-made arthrometer (2) designed to passively invert the ankle joint from 0° to 5°,10° and 20° and thereby elongating ATFL. ATFL length and strain were assessed via B-mode ultrasonography (15 MHz, 2cm depth) taking the curved path of the ligament into account, and strain referenced to 0° inversion. Shear-wave velocity (SWV; 15MHz, 4cm depth) - as an index of the ligament’s elastic material property, was measured via a 25mm region-of-interest within the mid-part of the ligament with the probe stabilised with a mechanical arm over a 2cm gel-pad. RESULTS: ATFL length, strain and SWV increased with increasing inversion angle (P<0.001) independent of the analysed group and limb. ATFL length and strain increased more in the involved limb vs. non-involved limb of injured participants (P<0.001), but did not differ between limbs in the control group. As such, the involved and non-involved measurements were compared separately to the average ATFL data from the control group and the involved limb showed a greater length at 0° (21.8±2.5mm vs 19.5±2.5mm, respectively; P<0.01) and remained longer through to 20° inversion (25.2±2.7mm vs 20.7±2.6mm, P<0.001), reaching a factor of 2.2 compared to the control group strain (15.9±7.0% vs 7.3±2.9%; P<0.001). SWV was only different at 5° (2.43±0.26m/s vs 2.33±0.30m/s P<0.05) and 10° (2.64±0.24m/s vs 2.56±0.25m/s P<0.05) inversion. There were no differences in ATFL properties between the non-involved and control limbs (P>0.05). CONCLUSION: The maximum ATFL strain reported in the involved limb of participants with a history of LAS are above yield threshold (~13%, 1) and close to ultimate strain (~20%, 3) values reported during ex vivo mechanical testing. This suggests maladaptive changes in ligament biomechanical properties following LAS injury. Our non-congruent findings between strain and SWV measurements further suggest that tensile are more affected than transient properties in response to the injury. Thus, interventions that increase tensile stiffness of the ATFL following injury are required. REFERENCES: 1) Siegler et al., Foot and Ankle International, 1988 2) Best et al., Knee Surgery, Sports Traumatology, Arthroscopy, 2016 3) Colville et al., American Journal of Sports Medicine, 1990
Read CV Fenja DeisterECSS Paris 2023: OP-BM03
INTRODUCTION: The semitendinosus (ST) is important for actions such as sprint performance [1]. Distal ST tendon harvesting for anterior cruciate ligament reconstruction (ACLR) substantially alters ST morphology and induces knee flexion (KF) weakness. As individual muscles within a synergist group specialize in different tasks [2], ST function cannot be compensated for by the other hamstrings [3]. Between-leg differences in isometric strength at 90° of KF strongly relate to ST muscle changes after ACLR [3,4]. Angle-specific strength decrements are also evident during concentric strength testing [5]. Nonetheless, isokinetic peak torque is still used as a clinical measure following ACLR. Here, we compared KF torque metrics from isometric and isokinetic tests in individuals post-ACLR with an ST autograft, hypothesizing that isokinetic peak torque would not relate to angle-specific strength losses. METHODS: Ten individuals (6 female, 27.2±4.9 y, 1.72±0.10 m, 72.6±13.4 kg, 13.9±3.4 months post-ST autograft ACLR) performed unilateral strength tests (System 4 Pro, Biodex) in the prone position. Maximal voluntary isometric contractions (MVIC) were performed at 15°, 45°, 60°, and 90° of KF [3]. Maximal concentric and eccentric contractions were preloaded at 10-20 Nm (depending on participant MVIC) and performed at 60°/s between 5°-95° of KF. For each contraction type, peak instantaneous torque was obtained from a minimum of three separate efforts. To obtain angle-specific metrics (15°, 45°, 60°, 90°) from isokinetic actions, torque-angle curves were averaged across the two best maximal efforts. Repeated measures ANOVAs and Pearson’s correlation coefficients were used to compare torques between legs, angles, and contraction types. RESULTS: For all contractions, ACLR legs were weaker than contralateral legs at 45°, 60°, and 90° (p<0.001), but not at 15° (p=0.097). Between-leg differences in torque were larger at 90° than at 15°, 45°, and 60° (p≤0.004). Although peak torques (~20°) were lower (~9%) for both isokinetic modes on the ACLR compared to contralateral leg (main effect: p=0.018), magnitudes were substantially less than at 90°, and between-leg differences in isokinetic peak torque did not significantly correlate with differences at 90°, regardless of contraction mode (r≤0.539; p≥0.108). Some individuals who had “recovered” (e.g., <5% difference in isokinetic peak torque) had large between-leg differences in KF torque at 90° (>30%). CONCLUSION: Between-leg differences in isokinetic KF peak torque are not related to important angle-specific torque metrics. As ST substantially contributes to 90° KF torque [3], we conclude isokinetic peak torque does not provide information on the recovery of ST. Thus, isokinetic peak torque should not be used to inform clinical decisions and treatments, particularly for athletes requiring high-velocity actions such as sprints, where ST is important [1]. REFERENCES: 1. Kawama 2024 EJSS 2. Lieber 1997 JEB 3. Kositsky 2024 ABME 4. Sasahara 2014 Knee 5. Hart 2022 SJMSS
Read CV Adam KositskyECSS Paris 2023: OP-BM03