Effect of Long-Term Electrical Spinal Cord Stimulation on Expression of Non-Reciprocal Inhibition α-Motoneurons of Human Skeletal Muscles

It is known, transcutaneous electrical spinal cord stimulation (tESCS) in the T11-T12 level of the thoracic vertebrae increases the power capabilities of the leg agonist muscles. One of the inhibition spinal mechanisms that protects skeletal muscles from excessive force is non-reciprocal inhibition. Taking into account the biological role of non-reciprocal inhibition, the aim of the study was to research the effect of long-term tESCS on expression of non-reciprocal inhibition of soleus muscle α-motorneurons in humans at rest and when holding a weak static force. Materials and methods: the study involved 22 healthy male subjects aged 27 to 35 years. Non-reciprocal inhibition of α-motorneurons was recorded during the 20-minute tESCS in the T11-T12 level of the thoracic vertebrae at rest, in combination with arbitrary muscular effort (5% of MVC) and after its impact. Results: TESCS at rest resulted in the weakening of non-reciprocal inhibition within 20 minutes of exposure and 10 minutes after the end of stimulation. TESCS in combination with arbitrary muscular effort in 5% of the MVC increases the activity of non-reciprocal inhibition for 20 minutes of stimulation and 10 minutes after its end. The proposed physiological mechanisms underlying the effect of long-term tESCS on expression of non-reciprocal inhibition are discussed.