Influence of Body Weight Support on Normal Human Gait: Development of a Gait Retraining Strategy

Abstract

The recovery of locomotion, following interactive training with graded weight support, in the adult spinal cat has led to the proposal that removal of body weight may be a therapeutic tool in human gait retraining. There would be benefits, however, in knowing normal responses of humans to partial weight bearing before applying this strategy to patients. In this study, 10 nondisabled male subjects walked on a treadmill while 0%, 30%, 50%, and 70% of their body weight was supported by a modified climbing harness. To dissociate the changes attributable to walking speed from those attributable to body weight, each subject walked at the specified body-weight-support (BWS) levels and at full weight bearing (FWB) at the same speed. Simultaneously, electromyographic data from the right leg muscles, footswitch signals, and video recording of joint motion were collected. The FWB and BWS gaits appeared similar, except at the highest level of BWS studied (ie, 70% of BWS). Significant differences among other BWS and FWB trials at comparable speeds included decreases in percentage of stance, percentage of total double-limb support time, and maximum hip and knee flexor swing angle. Other adaptations to BWS were a reduction in the mean burst amplitude of the muscles that are active during stance and an increase in the mean burst amplitude of the tibialis anterior muscle. The possible implications of this new gait retraining strategy for patients with neurological impairment are discussed. [Finch L, Barbeau H, Arsenault B. Influence of body weight support on normal human gait: development of a gait retraining strategy.

Muscle activation during unilateral stepping occurs in the nonstepping limb of humans with clinically complete spinal cord injury

“…This suggests that the increases in EMG amplitude during limb loading were not caused by stretch reflex activation. Previous studies have found that the EMG amplitude increases in proportion to lower limb loading in nondisabled and spinal cord-injured humans, 4,[16][17][18] but those studies have examined normal bilateral stepping where the limb undergoes considerable flexion and extension with each step.…”

Plasticity After Spinal Cord Injury: Relevance to Recovery and Approaches to Facilitate It

“…Although no connection to the brain existed, this locomotor "recovery" could be amplified with treadmill training, ultimately resulting in weight-supported stepping on a treadmill [38,39]. The promising results of treadmill training in cats were soon translated to clinical applications [40], where it is now viewed as a potent therapy (reviewed in van Hedel and Dietz [41]). Although it has been argued as to whether weight-supported treadmill training is superior to weightsupported over ground locomotor training [42], it is accepted that it significantly aids rehabilitation training.…”

ZeroG: Overground gait and balance training system

“…While the conceptual framework for utilizing BWS is beyond the scope of the present discussion, at its core, unloading the paretic lower limbs allows patients with gait impairments to practice a high number of steps in a safe, controlled manner (Hidler et al [5]). Varying BWS can also be used to alter the intensity of gait therapy since unloading the patient decreases both muscle demands and, subsequently, muscle forces throughout the lower limbs [6][7][8]. This can be particularly important during the early stages of neurological injury when patients are often sick and have poor cardiovascular endurance [9].…”