Analysis of Lower Limb Asymmetry in Drop Jumps from Different Heights

This study aimed to investigate the effects of lower limb muscular asymmetry on the bilateral variations observed in high platform drop jumps, with a particular emphasis on the side-to-side differences in both the initial and secondary ground contacts during these jumps. Seventy-one students from the Physical Education department were selected to perform countermovement jumps. Participants were further classified into two groups, strength symmetry and strength asymmetry groups, based on the asymmetry strength index calculated from data collected via the force plates. Drop jumps were performed from three designated heights, i.e., 30 cm, 40 cm and 50 cm (DJ30, DJ40 and DJ50, respectively). The mixed design two-way ANOVA revealed notable differences between the stronger and weaker legs. Significant differences were observed in the timing of the peak vertical ground reaction force at the first ground contact of the DJ30 (p < 0.05) and in the shape factor of the push-off phase of the DJ40 (p < 0.05). The unilateral preference might lead to an increased risk of lower limb injuries. Prolonged training may exacerbate the degree of lower limb asymmetry. Potentially these findings can provide valuable suggestions for athletes and coaches in their training.