Comparison of Jump-Landing Biomechanics during and after Fatigue: Investigation on the Optimal Timing of Screenings under Fatigue
(Stefan Vermeulen, Camilla De Bleecker, Valentien Spanhove, Veerle Segers, Tine Willems, Philip Roosen, Roel De Ridder, Jos Vanrenterghem)

Fatigue has been considered a risk factor for sports injuries, modulating full-body jump-landing biomechanics. Biomechanical assessments of jump-landing manoeuvres are typically performed before and after short-term fatigue protocols, but changes during the protocol are often neglected. Therefore, this study investigated spike jump-landing strategy alterations during and following a short-term fatigue protocol in volleyball. Forty-three healthy, adult, male volleyball players participated in this study. Three-dimensional full-body kinematics were collected when performing spike jump-landings before, during and after a short-term fatigue protocol specific for volleyball. Full-body sagittal plane joint angles were calculated and analysed with curve analysis using one-way repeated measures ANOVA and post-hoc paired sample t-tests to investigate fatigue effects (p < 0.05). A significant main effect of fatigue was found for all kinematic variables (p = 0.015−0.041). More specifically, more pelvis-trunk flexion and less hip, knee, and ankle (dorsi-) flexion were observed during and after the protocol compared to baseline (p = 0.001−0.003). Moreover, less hip and knee flexion was observed during the protocol compared to after fatigue (p = 0.001−0.005). In conclusion, significant kinematic changes were found with fatigue, and these were somehow more pronounced during fatigue, possibly due to decreased attention towards the jump-landing task execution. A decision tree was provided to help researchers, coaches and/or clinicians in determining whether screenings should be better performed during or after fatigue, based on practical considerations.