How is walking speed related to muscle strength? A study of healthy persons and persons with late effects of polio.

Abstract

To evaluate the relationship between walking speed and muscle strength in the lower extremities in healthy persons and in persons with late effects of polio and to compare the models for these relationships. Retrospective analysis. University hospital department. An urban sample of 144 healthy men and women (age range, 40-79 y) and 234 (146 women, 88 men) subjects with late polio. Not applicable. Muscle strength in the lower extremities was measured and combined into an index. Walking speed for spontaneous and maximal walking was measured. A nonlinear regression model was developed. Evidence was provided for the nonlinear relationship between walking speed and strength. A specific strength threshold could not be identified. The asymptote of this curve for maximal walking was 2.57 m/s in the healthy group and 2.02 m/s in the subjects with late effects of polio. A high body mass index (>25 kg/m2) lowered the asymptote. It is important to prevent strength decrease that approaches the critical level where a further reduction affects walking speed more evidently. The difference in the relationship between muscle strength and walking speed for the 2 groups studied may partly depend on biomechanic imbalance between muscle groups.