Biomechanical analysis of unilateral landings in female volleyball players after a dynamic and combined dynamic-static warm-up

Abstract

A warm-up is an important period before training or competition to prepare an athlete for the physical demands of subsequent activity. An ongoing debate exists in the current literature as to whether static stretching should be included in a warm-up practice to reduce injury risk during sport. Prior research has extensively focused on the effects of static and dynamic warmups in relation to jumping performance, however, limited research has examined the biomechanical nature of landings following these warm-up practices. Compared to males, female athletes display landing mechanics that may increase the risk of lower extremity injury. The sport of women’s volleyball require athletes to perform many unilateral landing tasks that, compared to bilateral maneuvers, further enhance injury risk. In the present study, twelve female, collegiate-level volleyball players performed unilateral landings on the dominant and non-dominant limb both pre- and post-dynamic (DWU) and combined dynamic-static (CDS) warm-ups. Kinetic and kinematic variables of interest were measured at the hip and knee during the landing phase of a volleyball-simulated jump-landing maneuver. A significant three-way interaction (warm-up x limb x time) was observed for peak internal knee adduction moment and peak hip adduction angle. Non-dominant knee adduction moment increased (p = 0.013; d = 0.79) 1 minute post CDS warm-up, while hip adduction angle in the non-dominant limb decreased (p = 0.016; d = 0.38) 15 minutes post CDS warm-up. No other warm-up differences were detected, however, significant main effects of limb were determined, as the non-dominant limb demonstrated an increase in peak knee external rotation moment, internal rotation angle, and knee abduction angle. The landing patterns in the non-dominant limb may be due to altered hip and trunk mechanics during the jump-landings, potentially placing the non-dominant limb at a higher injury risk. Main effects of time were also revealed for peak knee internal rotation moment, knee abduction angle, and knee external rotation / internal rotation, potentially attributed to the frequency of jump-landings performed in this analysis. Static stretching following a DWU may acutely place a female volleyball player at a higher risk for a non-contact knee injury in the non-dominant limb, therefore it is recommended that athletes be allowed a rest period prior to training or competition if static exercises are included in pre-activity practices. Additional consideration must be given to limb dominance in this population, as training should incorporate single-leg landing technique and muscular strengthening exercises to reduce injury risk from repeated unilateral landings. The results of this analysis may provide practitioners with biomechanical information to determine warm-up protocols and training methods that adequately prepare a female volleyball athlete for sport demands.