Abstract
In the present study, we developed a method to quantify adaptive change in walking pattern during split-belt treadmill walking using a tri-axial accelerometer attached to the pelvis. Specifically, the acceleration signals were decomposed by Fourier analysis using stride frequency as the fundamental harmonics, and the amplitudes of the even harmonics were compared with those of the odd harmonics. If human walking is perfectly symmetrical, the acceleration patterns should be bi-phasic, resulting in comparatively larger even harmonics.
To evaluate the usefulness of the present accelerometer-based method, we investigated locomotor adaptation during split-belt treadmill walking on 5 human participants. At the beginning of the adaptation process, stance period and step length were longer on the slow leg than on the fast leg. As locomotion was adapted to the different speed condition, the stance period and step length decreased on the slow leg and vice versa on the fast leg, indicating that locomotion became more symmetrical. We observed that the even harmonics of the anteroposterior acceleration signals increase over the course of adaptation, indicating that change in asymmetry in human walking was successfully quantified using the proposed method. Therefore, the present methodology may serve as a simple yet effective mean to quantitatively evaluate change in locomotor symmetry in gait rehabilitation using a sprit-belt treadmill.
