Effects of limb loading on the lower-limb electromyographic activity during orthotic locomotion in a paraplegic patient.

The relationship between limb loading and lower-leg electromyographic (EMG) activity was examined during orthotic locomotion in a complete paraplegic patient. The level of limb loading was modified by a hanging system. Surface EMG in the lower-leg extensor and flexor muscles was unilaterally recorded together with the load signal on the ipsilateral sole. The motion of the knee and the ankle joints was minimized, which means that the change in length of the examined muscles was minimum. The muscles were activated synchronously with the locomotor movement and the magnitude of the extensor activity was changed relative to the peak load on the sole. It is conceivable that the spinal cord interpreted the load information and modified the EMG output in the anti-gravity muscles even in the absence of stretch reflexes.