Evaluating Performance During Maximum Effort Vertical Jump Landings.

The ability to rapidly complete a jump landing has received little attention in the literature despite the need for rapid performance in a number of sports. As such, our purpose was to investigate differences between groups of individuals who land quickly (FAST) and slowly (SLOW) relative to peak vertical ground reaction forces (vGRFs), loading rates, rates of vGRF attenuation, contributions to lower extremity mechanical energy absorption at the involved joints, and the onsets of preparatory joint flexion/dorsiflexion. Twenty-four healthy adults (26.1 [3.3] y, 75.7 [18.9] kg, 1.7 [0.1] m) were stratified into FAST and SLOW groups based on landing time across 8 jump-landing trials. Independent t tests (α = .05) and effect sizes (ESs; large ≥ 0.8) compared differences between groups. A greater rate of vGRF attenuation (P = .02; ES = 0.95) was detected in the FAST group. The FAST group also exhibited greater contributions to lower extremity energy absorption at the ankle (P = .03; ES = 0.98) and knee (P = .03; ES = 0.99) during loading and attenuation, respectively. The SLOW group exhibited greater contributions to energy absorption at the hip during loading (P = .02; ES = 1.10). Results suggest that individuals who land quickly utilize different energy absorption strategies than individuals who land slowly. Ultimately, the FAST group's strategy resulted in superior landing performance (more rapid landing time).