What is the relationship between lower body strength and gait following stroke?

Abstract

INTRODUCTION/BACKGROUND: Despite the logical link between strength and walking ability, interventions which increase strength in people with neurological impairments have typically found little improvement in gait. This suggests that rehabilitation programs may not be targeting the ideal muscle groups. The aim of this study was to determine which lower limb muscle group had the strongest relationship with gait velocity and joint power generation during gait. METHOD: Sixty-three adults following stroke (age: 60 years, 34 male) were recruited in a multi-site, multi-national study. Isometric strength of seven lower limb muscle groups was assessed with hand-held dynamometry. Gait velocity was assessed with the fast paced 10m walk test. Three-dimensional gait analysis was performed in a sub-group of participants to examine joint power generation during gait. Associations between measures were assessed with Spearman's correlations and linear regression models were used to examine relationships. To statistically compare lower limb muscle groups, a partial F-test was used. RESULTS: The isometric strength of all seven lower limb muscle groups had a significant association with gait velocity (rho = 0.43-0.72, p<0.05). When comparing each muscle group, the ankle plantarflexors and hip flexors had the strongest relationship with gait velocity. Ankle plantarflexor isometric strength also had a significant association with ankle power generation during gait (rho = 0.75, p<0.05). The most commonly assessed and treated muscle group in prior studies, the knee extensors, had very weak to moderate associations with gait velocity and power generation ( rho = 0.07-0.54). CONCLUSION: The strength of the ankle plantarflexors and hip flexors had the strongest relationship with gait, and plantarflexor strength also had a significant relationship with ankle power generation during gait. Future research should examine how treatment of ankle plantarflexor and hip flexor strength impacts upon gait function after stroke.