The effect of treadmill gait training on low-frequency depression of the soleus H-reflex: comparison of a spinal cord injured man to normal subjects.

H-Reflex recruitment curves were obtained at 0.1 and 1 Hz in the right soleus of an incomplete SCI man before and after training and on 12 neurologically normal individuals. Low frequency depression (LFD) was calculated by the formula: 1 - (H-wave amplitude at 1 Hz/0.1 Hz) x 100. Training consisted of treadmill walking at the speed matching his overground fast walking. The subject trained for 30 min every other day for 10 days under supervision and then continued three times a week for 4 months at a health club. Maximum H/M ratio of the right soleus (78%) was greater than that of the normals (67%) and did not change following training (79%). The mean LFD of the SCI subject was 24% prior to training compared to 42% for the normal subjects. Following training, LFD increased to 35%. In addition, the reflex threshold appears to have increased following training. This was accompanied by 47 and 45% increases in the subject's self selected and fast gait velocities, respectively. We conclude that training adaptations enabled the SCI subject to increase his gait velocity due to an improved ability to gate peripheral afferent feedback during gait.