Women’s Collegiate Volleyball Players Exhibit Kinetic Asymmetries during Sport-Specific Tasks

Abstract

Women’s volleyball demands frequent lateral movements and vertical jumps. Repetitive lateral movements in the same direction could lead to biomechanical asymmetries and a potential increased risk of lower extremity injury. PURPOSE:To identify and analyze biomechanical asymmetries in collegiate women’s volleyball players during sport-specific lateral and vertical jumping tasks. METHODS: Nineteen female collegiate volleyball players were analyzed using standard 3D motion capture techniques during a drop vertical jump (DVJ) from a 30-cm box and a reactive jump (REACT) task. For the REACT, participants began in an athletic stance awaiting a directional cue on a screen placed in front of them. Once directed, participants were instructed to jump laterally and then vertically as high and fast as possible to mimic a volleyball block. Repeated measures MANOVA models were used to identify asymmetries in kinematic and kinetic measures in the DVJ and REACT task (α=0.05). Paired t-tests identified asymmetries in reaction time during the REACT task. Limb symmetry indices (LSI) were calculated for significant findings. RESULTS:Significant kinetic asymmetries were identified for both the DVJ (p=0.01) and REACT (p=0.003) tasks, but no kinematic asymmetries were found in either task (p>0.05). During the DVJ, participants exhibited asymmetrical knee abduction (LSI=81%, p=0.03), ankle dorsiflexion (LSI=94%, p=0.03), and ankle inversion (LSI=30%, p=0.001) external joint moments and vertical ground reaction forces (LSI=93%, p=0.04). During the REACT task, participants exhibited asymmetrical ankle dorsiflexion (LSI=85%, p=0.03), and ankle inversion (LSI=73%, p=0.001) external joint moments. There were no differences in reaction times between the two limbs (p>0.05). CONCLUSIONS:Collegiate women’s volleyball players exhibit significant asymmetry in the knee and ankle during jumping and landing tasks. Interestingly, asymmetries were identified in kinetic variables but not kinematic variables. These findings indicate that screening, injury prevention and rehabilitation practices cannot solely rely on visual observation to identify lower extremity asymmetry in this athletic population.