(17) COUNTERMOVEMENT JUMP METRICS AND INJURY RISK: INDIVIDUALIZED SCREENING FOR PERFORMANCE OPTIMIZATION AND INJURY REDUCTION

Introduction: Team sports (TS), require high levels of physiological adaptations to anaerobic and aerobic pathways for peak performance. The high physiological workloads associated with TS can lead to increased injury risks (IR). Thus screening and monitoring athletes is common practice. The countermovement jump (CMJ) is widely used to assess performance and neuromuscular fatigue (NMF) as changes in the eccentric (EP), concentric (CP), and landing (LP) phases of the CMJ are sensitive to NMF. However, the influence of aerobic fitness (AF) and body composition (BC) in mitigating the impact of maximal aerobic exercise (MAE) on CMJ phases remains poorly understood.

Purpose: To determine the effect of MAE on CMJ phase metrics and control for AF and BC factors.

Methods: After a BodPod BC test participants (n=13, males=7, age=30.61±6.8yr, Ht=170.9±7.3cm, Mass=73.0±15.4kg) performed a warm-up, 2 CMJ, a MAE test to induce NMF, and 2 CMJ. Rest periods between CMJ attempts were 15-seconds. Multiple ANCOVAs with Tukey post hoc tests compared non-fatigued (NFC) and fatigued (FC) conditions on EP, CP, and LP CMJ metrics, controlling for age, MAE, FM, FFM, heart rate at ventilatory threshold (HRVT), and percent VO2 at ventilatory threshold (PVT). Peak force (PF), rate of force development (RFD), peak power (PP), and impulse (IMP) were computed relative to body mass. Alpha was set to < 0.05.  

Results: A significant main effect was observed for LP IMP (FC >NFC), no covariates were significant (Table 1). No main effects were identified for PF, RFD, and PP across all CMJ phases. EP had significant covariate effects of MAE, FM, FFM, HRVT, and PVT on PF. MAE was a significant covariate for RFD, while FFM and PVT were significant covariates for PP. For IMP, FFM and PVT were significant covariates. CP had significant covariates including age and MAE on PF, PVT on RFD, and MAE on PP. CP IMP had no significant covariates. LP, FFM was a significant covariate for PP, and both MAE and FFM were significant covariates for RFD. Age, MAE, and FFM were significant covariates for PP.

Conclusion: Responsiveness to group changes post-MAE was evident only in LP IMP, with significant covariate effects observed on all phases of the CMJ for both AF and BC. The findings exhibit the challenges of detecting group level NMF changes, as few significant changes were observed. However, the significant individual-level factors indicate the importance of screening individual responses to maximal exercise to identify those at greater IR during TS involving MAE. PRACTICAL APPLICATION: The protocol of the present study may provide a framework for sport scientists and strength and conditioning practitioners to work in tandem. Similar procedures could be used to screen athletes displaying post-MAE fatigue CMJ metrics associated with IR, enabling interventions to address athlete specific injury prevention needs, thereby optimizing performance and reducing IR at the individual level.

Acknowledgements: None