Effect Of Puberty And Gender On Landing Force And Jump Height

Abstract

PURPOSE Neuromuscular performance increases rapidly in males throughout pubertal development. A similar neuromuscular spurt is not typically found in females during the same stages of puberty. The hypothesis was that there would be no differences throughout pubertal tanner stages in neuromuscular performance in females while males would show a greater vertical at each stage of development. METHODS 275 middle school and high school athletes volunteered to participate in this study (87 females, 188 males). Subjects were recruited from preseason physical screening. Pubertal development (Tanner Stage) was assessed by trained physicians. Only those athletes who were classified as pubertal through post pubertal (Tanner Stages 2–5) were included. Each subject performed 2 drop vertical jumps (DVJ) from a box height of 31cm (Ford 2003). They were instructed to drop off the box, land and immediately perform a maximal vertical jump. A portable force platform was used to collect the landing from the box and the landing after the vertical jump (AccuPower, AMTI). Maximum vertical ground reaction force (MVGRF) was calculated at three different phases, drop landing (DL), drop take-off (DT), and vertical landing (VL). Maximum vertical jump height (V) was also calculated from each trial. The ratio of the MVGRF (DL/DT) at the eccentric and concentric phases was calculated. A 2 ± 4 ANOVA (Gender*TannerStage) was utilized. RESULTS There was no difference in vertical jump height (V) throughout the developmental stages in females, males increased their vertical jump height by 16.3%, 13.4% and 7.9% at each stage of pubertal development (p = 0.002). The ratio DL/DT was decreased in males throughout pubertal stages while females showed no change (p = 0.047). The ratio of maximum force during the landing after the vertical to the maximum vertical jump (VL/V) decreased in males throughout pubertal stages while females had no change (p = 0.024). CONCLUSIONS These findings confirm the absence of a neuromuscular spurt in females and its presence in males. Lack of the neuromuscular spurt and force attenuation may play a role in the increased risk of ACL injury in female athletes. Injury prevention programs improve neuromuscular control and reduce ACL injuries in young females. The divergence in ACL injury rates between male and female athletes begin around age 12, when the majority of females are pubertal and their impact forces fail to be attenuated.