A single bout of resistance exercise does not affect nonlinear dynamics of lower extremity kinematics during treadmill walking.

Peripheral fatigue has been known to result in altered force output and muscle recruitment patterns by the CNS. These changes may affect lower extremity movement during gait, and such behavior may present implications for the interpretation of nonlinear analysis of gait in situations where a subject might become fatigued. The purpose of this study was to examine the effects of a single bout of resistance training on lower extremity movement during treadmill walking in healthy subjects. Fifteen recreationally active subjects performed two 10min trials of treadmill walking at their preferred speed while knee and ankle kinematics of their right limb were recorded via optical motion capture. Between walking trials, subjects performed a series of lower extremity resistance exercises designed to induce moderate muscular fatigue. Detrended fluctuation analysis of stride length and stride time revealed that statistical persistence was unaffected by moderate muscle fatigue. Estimates of finite-time maximal Lyapunov exponents for ankle angle, knee angle, and vertical ankle movement over the short (0-1 stride) and long (4-10 strides) term were also unaffected by a single bout of resistance training. These results suggest that control of locomotion in healthy individuals, as measured by the nonlinear dynamics of lower extremity movement used here, is relatively robust to moderate muscle fatigue. Additional work with greater levels of fatigue will be necessary to fully characterize the effects of muscular fatigue on gait.