Influence Of Knee Extensor Strength On Spatiotemporal Gait Parameters In Adults With Prader-willi Syndrome

Abstract

Adults with Prader-Willi Syndrome (PWS) are at greater risk for falls, which may be due to impaired muscle and gait performance. PURPOSE: To compare spatiotemporal gait parameters between adults with and without PWS, and to explore associations between knee extensor strength and spatiotemporal gait parameters in adults with PWS. METHODS: 10 adults with PWS, and 10 controls with and 10 without obesity completed isometric knee extensor (KE) strength assessments and gait analyses. Strength outcomes included peak KE torque, and early and late KE rate of torque development (RTD). Gait outcomes included speed, step length, step width, double support time, cadence, and gait-stability ratio (GSR). Step length and width were normalized to height, and strength outcomes were normalized to lean mass. Gait and strength outcomes were compared between groups with one-way MANOVA, and post hoc tests were made using Tukey’s HSD. Associations between strength and gait outcomes were explored using 1-tailed Pearson and Spearman correlations in the group with PWS. RESULTS: Gait (Pillai’s Trace = 0.86, p = 0.01) and strength outcomes (Pillai’s Trace = 0.52, p = 0.01) differed between groups. Adults with PWS had shorter step length (p < 0.01), longer double support (p = 0.01), and slower gait speed (p = 0.02) compared with controls without obesity, and higher GSR compared with controls without obesity (p = 0.01) and with obesity (p = 0.04). Adults with PWS had less KE torque (p < 0.01), early (p < 0.01) and late (p < 0.001) RTD compared with controls without obesity; and less KE torque (p = 0.01), less early (p = 0.03) and late (p = 0.01) RTD. In adults with PWS, greater KE torque was associated with faster speed (rho = 0.57, p < 0.01), smaller step width (r = -0.62, p = 0.03), shorter double support time (r = -0.57, p = 0.04), and lower GSR (rho = -0.79, p < 0.01). Greater late RTD was associated a faster speed (rho = 0.79, p = 0.01), lower GSR (rho = -0.71, p = 0.01), and longer step length (rho = 0.71, p = 0.01). CONCLUSIONS: Adults with PWS have different spatiotemporal gait parameters compared with controls that contribute to slower gait speed and reduced mobility. Larger GSR may reflect an adaptive strategy to increase ground contact time and avoid dynamic portions of the gait cycle. Improving knee extensor function may be useful to increase gait performance in adults with PWS.