Gender and Limb Differences in Dynamic Postural Stability During Landing

Abstract

To determine if gender and limb dominance affect dynamic postural stability and vertical ground reaction force data during jump landings. Secondary objective was to assess the reliability of the dynamic postural stability index (DPSI). A mixed model (2 genderx2 limb) repeated measures design was used to determine the effects of gender and limb dominance on dynamic postural stability. Subjects were required to perform a two-legged jump to a height equivalent of 50% of their maximum vertical leap, land on a single-leg and balance for three seconds. Sports Medicine Research Laboratory. Forty healthy subjects (20 men, 20 women) participated in this investigation. The DPSI and its directional components quantified dynamic postural stability during a single-leg jump landing. Normalized vertical ground reaction force data quantified energy absorption. DPSI values revealed that females had significantly different dynamic postural stability as compared to males in the vertical plane [T (78)=-4.2, P<0.01], and in the composite score (dynamic postural stability index) [T (78)=-6.3, P<0.01]. In addition, females had significantly higher peak vertical ground reaction forces [T (78)=-13, P=0.01] than males. The DPSI also showed excellent reliability (ICC=0.96), with a 95% confidence interval ranging from 0.94 to 0.97. The results indicate that females have higher dynamic postural stability scores in the vertical direction as well as the composite score. This suggests that females used different dynamic postural stability strategies than males. There were no side-to-side dynamic postural stability differences between healthy contralateral limbs.