THE EFFECTS OF FATIGUE ON LANDING IMPACT FORCES AND POSTURAL STEADINESS IN COLLEGIATE VOLLEYBALL PLAYERS

Background: The onset of exhaustion can reduce the performance of an athlete and may add to the risk of injury. This establishes the necessity to understand when and how the athlete’s performance is altered as they become fatigued in competition or practice. The aim of this study was to determine the effects of fatigue on dynamic and static tasks in collegiate volleyball athletes by implementing a fatiguing jump protocol. Methods: To replicate an in-game or in-practice situation, five sets of 30 countermovement jumps (CMJ) at 85% maximal height was implemented. Prior to the fatigue protocol, a baseline measure of CMJ height, ground reaction force metrics, and postural steadiness center of pressure (COP) were collected on a force plate. After each simulated set, dynamic and static tasks were re-assessed to identify changes stemming from the onset of exhaustion via CMJ and balance assessment, respectively. The CMJ was quantified by the net positive impulse, the rate of force development at takeoff, jump height, and peak landing force. Balance was quantified by mean distance, mean velocity, mean frequency, and the 95% confidence ellipse of the COP signal during eyes open and eyes closed. Lastly, the overall fatigue was quantified at the conclusion of the protocol with a self-reported RPE score. Results: The outcome of the study indicated that the participants had reached severe to very severe levels of perceived fatigue (RPE = 6.3 ± 1.0). There were no significant changes in the dynamic task; however, the static task metrics results showed significant reductions (p ≤ 0.05) in mean distance, mean velocity and 95% confidence ellipse of the COP signal. Specifically, balance metrics increased compared to baseline measures early in the fatiguing protocol before plateauing for the remainder. Discussion: These findings indicate that our sample cohort was highly fatigue resistant to degradations in a dynamic task, while losing some postural control during static tasks. These results suggest that dynamic tasks, that are ...