Changes in knee joint function over a wide range of walking speeds

Objective. Changes in patterns of knee joint flexion-extension rotations, moments and powers were investigated during the stance phase across a wide range of walking speeds that includes the very slow speeds used by many patients referred for gait analysis. Design. Each subject walked at 25, 50, 75, 100, and 125% of a scaled natural speed of 0.785 statures.s(-1). Background. The results of earlier studies suggest that control subjects, as they walk at progressively slower speeds, increasingly use a large internal knee flexor moment in the early stance phase. Methods. Eighteen healthy adult subjects (nine male and nine female) were tested. Results. The shapes of the mean patterns were similar for the three fastest, most natural walking speeds. At the two slowest speeds, however, subjects used little knee flexion and small knee moments through mid-stance, resulting in negligible joint power through the first 80% of the stance phase. At these speeds, most subjects had moment patterns that could not be classified with confidence as 'normal' or as predominantly flexor or extensor. Only four subjects had knee flexor moment patterns at the slowest speeds, and these included much smaller flexor moments in the early stance phase than in some previous reports.