Role of the cervical and lumbar proprioceptors during stepping. An electromyographic study of the muscular activities of the lower limbs.
To obtain evidence of the role of the cervical and lumbar proprioceptors during stepping, the following investigations were carried out. 1) 10 normal, healthy subjects and vertiginous patients, particularly those with lumbar pain, were examined. 2) Fukuda's stepping test was first carried out, followed by two modified stepping tests, i.e., stepping after fixing the waist with a corset and after fixing the neck with a collar. 3) Electromyograms (EMGs) of the gastrocnemius muscles of the extensor of the lower limbs were analysed as regards the foot contact with the ground. The following results were obtained. In the original way of Fukuda's stepping test, normal subjects tended to show EMG discharges from the gastrocnemius muscles before foot contact with the ground, whereas in the modified stepping tests, the generation of EMG discharges was delayed, especially in the test requiring fixing of the waist with a corset. The results of these stepping tests were reversed in the vertiginous patients, particularly in those with lumbar pain. We conclude that the lumbar proprioceptors participate especially in the smooth performance of stepping by promoting the anticipatory activity of the extensor of the lower limbs.