Speed-dependent deviations from a straight-ahead path during forward locomotion in healthy individuals

Objective: In subjects with unilateral vestibular malfunction, running is associated with less departure from the straight-ahead path than walking. The purpose of this study was to broaden the scope of these observations by investigating whether they can be generalized to healthy subjects. Design: Healthy blindfolded subjects were asked to traverse a 10-m straight path while walking at a self-selected slow speed, walking at a fast speed, or running. Gait speed and mediolateral feet placement were monitored, and departure from the straight-ahead path (path integration) was determined. Results: In healthy subjects, similar to subjects receiving unbalanced vestibular information, departures from the straight-ahead trajectory (namely, path integration) were larger in slow walking than in running. Conclusions: In healthy subjects, variation in foot placement between the acts of walking and running seem to account for the enhanced path integration found during running. Perhaps consideration of these findings is also relevant for the interpretation of speed-dependent path integration in subjects receiving abnormal unilateral vestibular inputs.