Comparison of soleus H-reflex modulation after incomplete spinal cord injury in 2 walking environments: treadmill with body weight support and overground.

Abstract

To investigate a walking environment effect on soleus H-reflex modulation during walking in persons with motor incomplete spinal cord injury (SCI) and noninjured controls. Pretest and posttest repeated-measures quasi-experimental controlled design. Locomotor training laboratory. Eight adults with incomplete SCI and 8 noninjured age- and speed-matched controls. Walking overground with a customary assistive device and brace at a self-selected, comfortable walking speed was compared with walking on treadmill with 40% body weight support (BWS) and manual trainers for leg and trunk movement guidance. Mean soleus H-reflex amplitude (H/M ratio) was recorded during midstance and midswing phases of walking. The H/M ratio was 33% smaller in stance phase (P=.078) and 56% smaller in the swing phase (P=.008) of walking on the treadmill with BWS and manual assistance compared with overground in the incomplete SCI group. The H/M ratio in the incomplete SCI group was significantly greater compared with noninjured controls in the stance and swing phases of overground walking (P=.001, P=.007, respectively). Soleus H-reflex modulation in the 2 walking environments did not differ significantly in the noninjured population. Training walking on a treadmill with BWS and manual assistance to approximate the kinematics and spatiotemporal pattern of walking may be a more optimal environment to aid in normalizing reflex modulation after incomplete SCI when compared with conventional gait training overground.