Effects of lower limb muscle fatigue on countermovement jump, dynamic balance performance and perceived stability among elite youth netball players with chronic ankle instability

Study aim: This study aimed to investigate the effects of lower limb muscle fatigue on jumping performance, balance, and perceived stability in elite youth netball players with chronic ankle instability (CAI).Material and methods: A total of 36 elite youth netball players were recruited from National Sports Schools using purposive sampling. The severity of functional ankle instability was assessed using the Cumberland Ankle Instability Tool. Jumping performance and dynamic balance were measured using a force plate and the Y Balance Test, respectively. The experimental protocol involved a submaximal countermovement jump (CMJ) attempt followed by a fatigue protocol consisting of consecutive maximal bilateral CMJs. Statistical analysis was performed using IBM SPSS statistical software.Results: The study found no significant effect on peak velocity but a significant reduction in peak force, peak power, flight time, and jump height after completing the fatigue protocol. Post-hoc comparisons showed significant reductions in peak force, power, flight time, and jump height before the stretch-shortening cycle (SSC) protocol compared to values after 5 and 10 minutes of the SSC protocol (post-5 and post-10 SSC).Conclusion: The study results suggest that fatigue is a risk factor for sports injuries, particularly in the ankle during jumping performance, and that fatigue does not contribute to dynamic stability.