Influence of Treadmill Design on Rearfoot Pronation During Gait at Different Speeds

Abstract

1807 Understanding the structure and dynamic function of the foot is the necessary for recognizing and treating mechanical foot dysfunction. Often the dynamic function of the rearfoot, considered a key element of overall foot function, is measured during treadmill locomotion. PURPOSE: To determine the influence of different treadmills on the motion of the foot during gait. METHODS: The kinematics of the right subtalar joint in 24 volunteers walking at three speeds on two motorized treadmills were examined. The two treadmills (a wide width and soft surface; a narrow width and hard surface) were selected to maximize motion differences. Maximal change in angular position (positive: supination; negative: pronation) about each volunteers subtalar axis were estimated during three gait phases: weight acceptance, mid-stance and push-off. A multiple-level, repeated measures analysis of variance was used to reject the hypothesis that phase, speed, and treadmill, and their interactions, did not influence subtalar motion. RESULTS: Statistical analyzes determined that the phase, treadmill, phase × treadmill and phase × speed effects were significant. Each of the three phases were different from each other (means: −4.2, – 2.9, 11.3 degrees). The treadmill design had a significant effect on subtalar position (F = 5.423, p = 0.29) albeit with moderate power (0.61). Specifically, collapsed over all speeds, the subject's feet on the narrow/hard compared to the wide/soft treadmill showed more pronation (0.44°), less pronation (0.46°) and more supination (1.44°) during the weight acceptance, mid stance and push off gait phases. CONCLUSIONS: It is important to note that an individual's rearfoot kinematics can be alter due to the design of the treadmill they are tested upon.Figure 2: Effect of walking speed and treadmil design on increased nearfoot pronation (negative) or supination (positive) during weight acceptance (top graph), mid stance (middle graph), and push-off (bottom graph) gait cycle phases.