THE EFFECTS OF FATIGUE ON LOWER LIMB BIOMECHANICS AND KINETIC STABILISATION OF THE TUCK JUMP ASSESSMENT

Abstract

Context: General and local muscular fatigue is postulated to negatively alter lower limb biomechanics; however, few prospective studies have examined the effect of fatigue on tuck jump performance. The tuck jump assessment (TJA) is a criteria-based visual screening tool designed to identify neuromuscular deficits associated with ACL injury. Utilization of kinetics during the TJA following an intense sport-specific fatigue protocol may identify fatigue induced neuromuscular deficits associated with ACL injury risk. Objective: To examine the effects of a sport-specific fatigue protocol on visually evidenced (2D) technical performance of repeated tuck jumps and lower limb kinetic stabilisation. Design: Cross-sectional Study. Setting: Laboratory. Patients of Other Participants: Twelve recreational female athletes (age 20.8 ± 2.6 yrs; height 170.0 ± 0.04 m; body mass 67.5 ± 7.4 kg). Intervention(s): Sport-specific fatigue protocol. Main Outcome Measure(s): Paired t-tests and effect sizes were used to evaluate differences and magnitude of differences in TJA scoring criterion, kinetics, and kinetic stabilisation pre-to post-fatigue. Results: A moderate increase (p < 0.01; g = 0.45) was observed for relative leg stiffness (kleg) post-fatigue. Ground contact time, flight time, jump height, net impulse, and centre of mass displacement (p ≤ 0.02) decreased with small to moderate effect sizes (g = 0.41-0.74). No differences were observed for TJA composite scores, peak VGRF, and stabilisation indices of kinetic variables (p > 0.05) following the fatigue protocol. Conclusions: Kinetic analysis of repeated 26 tuck jumps following a fatigue protocol identified an altered jumping strategy, that was not identifiable via visual 2D assessment. However, based on kinetic measures, fatigue induces a stiffer jumping strategy and practitioners should consider assessing load attenuation strategies that may not be visually evident when evaluating ACL injury risk factors in athletes who are fatigued.