A kinematic comparison of overground and treadmill walking.

OBJECTIVE: To compare overground and treadmill ambulation for possible differences in gait temporal variables and leg joint kinematics. DESIGN: A human subject trial of walking in two conditions. BACKGROUND: The treadmill is frequently used to simulate overground ambulation; however, the literature shows a wide difference of opinion as to whether the treadmill replicates the overground environment. METHODS: A total of 17 uninjured subjects walked overground at their preferred velocity. The treadmill was then set at the average velocity obtained in overground walking. Gait temporal variables and leg joint kinematics were analysed using the three dimensional (3D) Kinemetrix Motion Analysis System. The data were analysed separately for the two gender groups and for the groups combined. RESULTS: In the females, only the maximum hip flexion angle was significantly different in the two conditions with greater flexion occurring on the treadmill. For males, significant differences were noted between the two conditions for cadence and maximum knee flexion angle with greater values in the treadmill walking. When all subjects were compared, significant increases were seen during treadmill walking in hip range of motion, maximum hip flexion joint angle and cadence, while a significant decrease was observed in stance time. CONCLUSIONS: Statistically significant differences exist between overground and treadmill walking in healthy subjects for some joint kinematic and temporal variables. RELEVANCE: The results of this and other studies demonstrate that the kinematics of human walking differ in treadmill and overground ambulation. The next step in this line of research is to assess whether the kinematic differences in the two walking conditions are exhibited in different patient groups. If differences do exist in patient groups, then the interpretation of treadmill-based gait analysis findings should not be extended to that of ground walking, particularly where the patient has an impaired hip function, such as that exemplified after total hip replacement.