The Effect of Perturbation Time on Selected Spatio-Temporal Parameters of Gait

Abstract

The mechanisms that underlie suitable response in fall threatening situation are not well understood yet. Most of the knowledge has been obtained from slip and trip mimicking experiments and from subjecting individuals to external pushes. While most studies focused on balance responses where perturbations were delivered at foot strike in this study we examined how delaying perturbation onset to later stages of stance phase affect step length, step width and step time. The experiments were conducted on five healthy male subjects that were subjected to series of perturbation impulses of different amplitude, direction with respect to stance leg and onset delay. Results show that when perturbed in lateral direction with respect to stance leg healthy subjects increased step length and step time and decreased step width. However, the changes were less pronounced if the perturbation onset was delayed farther in stance phase. When perturbed in medial direction with respect to stance leg they decreased step length and step time and increased step width. However, the changes were less pronounced if the perturbation onset was delayed farther in stance phase. Results suggest that in healthy population perturbation onset plays important role in spatio-temporal responses.