Knee extension power, velocity and torque: relative deficits and relation to walking performance in stroke patients

Abstract

This study of hemiparetic stroke patients aimed to determine the nature and usefulness of dynamometer measurements of knee extension power compared to knee extension velocity and torque. Twenty subjects (mean age 63.7 years, time since stroke 70 days) performed maximum knee extension efforts on a Lido dynamometer. Specifically measured on each side were power and velocity during maximum velocity efforts and peak torque during isometric efforts. Subjects were timed while walking 7m at their 'most comfortable' and 'maximum safe' speeds. The mean knee extension performance deficits on the paretic side, compared to the nonparetic side, were 58.4% for power, 30.0% for velocity, and 44.5% for torque. The deficits were significantly different from one another. All muscle performance measures were correlated significantly with the gait speed measurements (paretic side r = 0.633-0.752; nonparetic side r = 0.448-0.650). Power measures were not clearly superior to velocity or torque measures for explaining gait speed. Measures of the paretic side, however, were superior to measures of the nonparetic side for predicting gait speed.