ECSS Paris 2023: CP-MH13
INTRODUCTION: Rupture of the anterior cruciate ligament (ACL) can make it difficult to return to high-performance sports such as artistic gymnastics, even after completing rehabilitation. Functional performance tests are essential for monitoring the load tolerance of injured structures, and can indicate when it is appropriate to return to sport (Dingenen und Gokeler, 2017). A Limb Symmetry Index (LSI) of at least 90% is often cited in the literature as a criterion for evaluating knee function. This study investigates the time at which the functional performance (FP) and LSI of a gymnast following an ACL injury return to pre-injury levels, thereby indicating their readiness to return to sport. A 6-year follow-up was conducted to assess long-term sustainability. METHODS: One elite female artistic gymnast (aged 24, with 18 years of training experience at a natio-nal competitive level) completed four functional tests — the Y-Balance Test (YBT), the Single-Leg Countermovement Jump Test (SLCMJ), the Single-Leg Hop for Distance Test (SLH) and the Speedy Jump Test (SJ) — at nine time points: t1 = 10 months pre-injury, t2 = 2 months post-injury, t3 = 2 months post-surgery, t4–t8 = 4 to 12 months post-surgery (bimonthly), and t9 = 6 years post-surgery Data were analysed descriptively using the LSI. At t9 an additional isokinetic strength measurement was performed at 60°/s, 180°/s, and 300°/s. RESULTS: At eight months (SLCMJ and SJ) and ten months (SLH) post-trauma, the LSI reached ≥90% across all tests. For the YBT, the LSI remained ≥90% from t1 to t9. Pre-injury FP levels were reached after 12 months for the SLCMJ and SJ. At t9, the LSI for the SJ was 92%, which was lower than the pre-injury value; however, all other tests showed values comparable to those at t1. Functional performance values declined at t9. The isokinetic results were 58.8/70.5/96.0% on the left leg and 55.5/74.1/85.3% on the right leg (60°/s, 180°/s, 300°/s). CONCLUSION: Readiness to return to sport was identified at 10 months post-surgery, with no subsequent injury during follow-up. As declines in the uninjured limb may limit the interpretability of the LSI, absolute functional performance should also be considered. In particular, outcomes from the dynamic Speedy Jump test and long-term monitoring using the Reliable Change Index are recommended. Right-sided hamstring weaknesses and slight asymmetries in the strength profile 6 years post- surgery pose risks. This case study highlights the importance of regular performance testing in order to obtain pre-injury reference data and optimise preventive and therapeutic training strategies. Further longitudinal studies incorporating absolute performance measures are needed to confirm these findings. Dingenen, B., Gokeler, A. (2017). Optimization of the Return-to-Sport Paradigm After Anterior Cruciate Li-gament Reconstruction: A Critical Step Back to Move Forward. Sports Med 47, 1487–1500. https://doi.org/10.1007/s40279-017-0674-6
Read CV Christiane WilkeECSS Paris 2023: CP-MH13
INTRODUCTION: The importance of kinetic chain transmission in the lower extremities has gained widespread attention in recent years. Previous studies have demonstrated that limited ankle dorsiflexion range of motion (DFROM) disrupts kinetic chain efficiency, leading to increased ground reaction force (GRF) characteristics and lower extremity stiffness during the landing phase of a drop jump. Such limitations may result in compensatory movements, such as reduced knee flexion displacement and increased knee valgus during landing, thereby elevating the risk of lower limb injuries, including anterior cruciate ligament (ACL) tears. While extensive evidence supports static stretching as a common and effective intervention for improving ankle DFROM, few studies have quantified the subsequent changes in kinetics, kinematics, and movement sequencing during jump landings. Consequently, it remains unclear whether improving ankle DFROM directly impacts athletic performance. This study aimed to investigate the effects of limited ankle DFROM on 2D kinematics and kinetics during jump landings and to explore the differences in these parameters before and after a stretching intervention. METHODS: Nine recreationally active individuals (mean age: 20.22 ± 1.79 years; height:1.69 ± 0.10 m; weight: 65.67 ± 9.95 kg) were recruited. Baseline measurements included ankle DFROM during a weight-bearing lunge test (WBLT) with a flexed knee, as well as kinetic and 2D kinematic data from countermovement jumps (CMJ), drop jumps (DJ), and the Landing Error Scoring System (LESS). Using a threshold of 36.5°, all participants were identified as having limited DFROM (mean: 27.96 ± 4.30°). The intervention consisted of a 5-week static standing straight-knee stretching protocol using a slant board at a 20°-30° incline, performed 3 days per week (5 sets of 30 seconds per session). Post-intervention data were collected following the 5 weeks. Non-parametric Wilcoxon Paired Sample signed-rank tests were used to analyze the differences in DFROM, CMJ, DJ, and LESS parameters before and after the intervention. RESULTS: A significant increase in ankle DFROM was observed following the static stretching intervention, with mean values rising from 27.96 ± 4.30° at pre-test to 36.46 ± 1.75° at post-test (p =.008). However, no significant differences were found in the kinetic parameters for CMJ and DJ, nor in the 2D kinematic parameters for the LESS (p >.05). CONCLUSION: A 5-week stretching intervention performed three times per week effectively enhances ankle range of motion, confirming that long-term, regular static stretching can mitigate limited ankle mobility. Nevertheless, despite the significant improvement in DFROM within the restricted group, no corresponding changes were observed in CMJ/DJ kinetics or LESS kinematics. This outcome indicates that only increasing ankle dorsiflexion angle may not exert an immediate or significant impact on overall athletic performance or landing mechanics.
Read CV YUN-TING TSENGECSS Paris 2023: CP-MH13
INTRODUCTION: Plantar cutaneous stimulation experienced during barefoot locomotion on uneven ground can acutely up-regulate sensorimotor gain and improve postural control. We tested whether a flexible, arch-stimulating inlay providing a longitudinal torsion cue elicits comparable effects during hybrid-running (HYROX-type) workout stations. METHODS: Randomized within-subject crossover. Hybrid athletes (age 37±8 y; height 176±9 cm; mass 75.4±13.6 kg; training 3.4±3.4 h weekly; n=70) completed one of two protocol halves (Group 1: Rowing, Farmer's Carry, Sandbag Lunges, Wall-Balls; Group 2: SkiErg, Sled Push, Sled Pull, Burpee Broad Jumps) interspersed with 50-step running bouts; all stations and runs were captured with pressure-sensitive insoles. Inlay/control order was randomized by period/sequence with 30 min rest. Primary endpoints: balance (i.e. absolute L-R asymmetry in %) and stability (i.e. medio-lateral load shift/instability index derived from plantar pressure trajectories) and pressure distribution (i.e. relative arch load share or dispersion index); secondary: variability (i.e. inter-step SD). Paired Delta (Insert−Control) per station/phase were tested with paired t-tests, 95% CI, Cohen’s dz, and FDR across metrics. Responders: SESOI (+2% for mean-metrics; −3% for SD-metrics); outliers excluded (|balance|>20). Ethics approved with anonymized, GDPR-conform processing. RESULTS: Balance asymmetry decreased consistently (mean −9.7%, range −4.8% to −13.0%; dz −0.06 to −0.15; all qFDR>0.05) along with instability across stations (mean −7.2%, range −5.6% to −8.3%; dz −0.12 to −0.28; all qFDR>0.05). Variability showed small reductions (mean −4.8%, range −2.9% to −5.7%; dz −0.04 to −0.32; all qFDR>0.05). In contrast, pressure distribution increased robustly (mean +7.7%, range +6.4% to +8.7%), surviving FDR in Farmers Carry (+7.5%, dz=1.05, qFDR<0.001), Wall Balls (+8.7%, dz=0.60, qFDR=0.031), Sled Push (+7.5%, dz=0.96, qFDR<0.001), Sled Pull (+7.5%, dz=0.91, qFDR<0.001), and Burpee broad jumps (+6.4%, dz=0.70, qFDR=0.005); Responder rates were high (balance 76–89%, stability 79–89%, variability 75–92%, pressure distribution 78–86%). CONCLUSION: The inlay elicited significant, reproducible changes in plantar loading across multiple stations, indicating an altered foot-loading strategy compatible with enhanced neuromuscular “pre-activation” and a more stable stance from which to generate force. This pattern aligns with a performance-relevant mechanism in hybrid events, where fatigue and rapid station transitions challenge postural control. Consistent reductions in asymmetry and instability, together with high responder rates, support the interpretation that sensorimotor plantar cues can improve movement economy and execution quality, with improved symmetry potentially lowering cumulative tissue stress and injury susceptibility. Beyond hybrid performance, future studies should test generalizability across disciplines and evaluate cautious applications in supervised return-to-activity contexts.
Read CV Nils FluethmannECSS Paris 2023: CP-MH13