Effect of treadmill walking on the stride interval dynamics of human gait.

Metronomic walking has been found to diminish the statistical persistence intrinsic to the stride interval time series of human gait. Since treadmill walking (TW) possesses a similar form of external pacing, we proposed to study the disruptions in the natural neuromuscular rhythms of gait during TW. Treadmill walking is a widespread rehabilitative tool, however, its effect on an individual's stride dynamics is not well understood. To better elucidate potential effects, we tested the hypothesis that TW without handrails would diminish the statistical persistence in an individual's stride interval time series. The scaling exponent (alpha) was employed in this study as a measure of the statistical persistence of the stride interval time series. Sixteen able-bodied young adults (mean age: 23.3+/-3.3 years) were instructed to walk at a self-selected comfortable pace for 15 min in three different conditions in a randomized order: (1) overground walking, (2) TW without holding a handrail (NoRail) and (3) TW while holding a front handrail (Rail). The alpha did not differ significantly between the overground and NoRail conditions (P>0.5). However, the alpha of the Rail condition (alpha=0.92+/-0.10) differed significantly from both the overground (alpha=0.83+/-0.06; P<0.015) and NoRail conditions (alpha=0.82+/-0.08; P<0.01). In contrast, stride interval variability did not change between walking conditions (P>0.5). These findings indicate that comfortable-paced TW does not diminish the intrinsic stride dynamics of human gait.