The strength of the ankle dorsiflexors has a significant contribution to walking speed in people who can walk independently after stroke: An observational study

Objective: To investigate the relationship between the strength of muscles of the affected lower limb and walking speed after stroke. Design: A cross-sectional observational study. Setting: University laboratory. Participants: Stroke survivors (N=60; mean age ± SD, 69±11y) 1 to 6 years poststroke, able to walk 10m independently without aids. Interventions: Not applicable. Main Outcome Measures: Maximum isometric strength of 12 muscle groups (hip flexors/extensors, adductors/abductors, internal/external rotators, knee flexors/extensors, ankle dorsiflexors/plantarflexors, invertors/evertors) of the affected lower limb was measured using hand-held dynamometry. Comfortable walking speed was measured using the ten-meter walk test. Results: Univariate analysis revealed that strength of the hip flexors (r=.35, P=.01), hip extensors (r=.29, P=.03), hip internal rotators (r=.30, P=.02), hip adductors (r=.29, P=.03), knee extensors (r=.27, P=.03), knee flexors (r=.30, P=.02), ankle dorsiflexors (r=.50, P=.00), ankle plantarflexors (r=.29, P=.03), and ankle evertors (r=.33, P=.01) were all positively associated with walking speed. Multivariate analysis (n=58) revealed that the combined strength of the ankle dorsiflexors and the hip flexors accounted for 34% of the variance in walking speed (P<.001). The ankle dorsiflexors accounted for 31% of the variance (P<.001). Conclusions: The strength of muscle groups other than the lower limb extensors, particularly the ankle dorsiflexors, has an important role in determining walking speed after stroke.