Is base of support greater in unsteady gait?

We investigated dynamic interfoot distance (IFD) throughout the gait cycle in people with unsteady gait caused by vestibulopathy and in people without known neuromuscular pathology. We expected that the subjects with unsteady gait would use a greater IFD than subjects without neuromuscular pathology and that this IFD would be correlated with other measures of locomotor stability.

Simultaneous whole-body (11-segment) dynamic kinematic data were collected from 22 subjects with vestibulopathy and 22 subjects without known neuromuscular pathology who were matched for age, height, weight, and body mass index. Two trials each of the participants' gait at preferred speed and paced gait at 120 steps/min were analyzed with a repeated-measures design with multiple dependent variables. Quantitative data were analyzed descriptively and with inferential statistics.

Interfoot distance at preferred gait speed did not differentiate unsteady subjects with vestibulopathy from the comparison subjects. Paced gait IFD total range and IFD in single-limb support differed between groups, but IFD at heel-strike did not. However, IFD at heel-strike, the traditional measure of "base-of-support width," was correlated with measurements of whole-body center-of-gravity stability (r=.32-.55).

Gait at preferred speed permitted the unsteady subjects and the comparison subjects to select similar IFD values, but at the cost of slower gait in the unsteady subjects. When required to walk at a "normal" pace of 120 steps/min, subjects with vestibulopathy increased their IFD. These data suggest that wide-based gait alone cannot differentiate between subjects with and without balance impairments. Base of support and other whole-body kinematic variables are mechanical compensations of vestibulopathic instability. Further studies are needed to determine whether development of active control of these whole-body control variables can occur after vestibular rehabilitation.