Sex-specific landing biomechanics and energy absorption during unanticipated single-leg drop-jumps in adolescents: implications for knee injury mechanics

Females aged between 13 and 17 years old possess the highest non-contact ACL injury incidence of any sex-age strata. Considering that energy absorption strategies have been associated with a reduced risk for sustaining an ACL injury, evaluating landing performance in youth athletes requires investigations beyond the kinematic level. The purpose of this study was to identify sex-specific energy absorption strategies in adolescent males and females, including the relationship between strength and the observed strategies. Thirty-one healthy adolescent athletes completed unanticipated single-leg drop-jump landings on their dominant limb. Sex-specific kinematics and lower-limb contributions to energy absorption were then compared over the landing phase for each jump. Pearson and Spearman correlation coefficients determined the relationship between isometric joint strength and the observed kinematics and energy absorption. Female participants absorbed a larger proportion of the landing energy at the ankle (p = 0.046, d = 0.75) and smaller proportion at the hip (p = 0.028, d = 0.85) compared to males. Females also reached larger peak negative joint power in their knee (p = 0.001, d = 1.1) and ankle (p = 0.04, d = 0.79). Hip extension strength was positively correlated with trunk flexion (r = 0.559, p = 0.001) and negatively correlated with forward pelvic tilt (r = -0.513, p = 0.003). Females adopted an energy absorption strategy which utilized the distal joints to absorb a larger portion of the landing forces and tended to absorb the forces later in the landing phase relative to males. The greater reliance on distal joints is correlated to reduced hip strength and may increase the risk for sustaining an ACL injury.