Effect of prolonged spinal cord electrical stimulation on skeletal muscle strength

The accumulated data from the previous studies show that transcutaneous electrical spinal cord stimulation (TESCS) can activate the locomotor-related activity in the spinal cord (spinal stepping generator) in healthy side-lying subjects with their legs suspended and control the coordination structure of arbitrary cyclic movements in humans. These facts suggest that long-term TESCS is able to increase skeletal muscle strength. The objective of this study was to explore the possibility to increase muscle strength by means of long-term rhythmic electrical spinal cord stimulation. Materials and Methods. The study involved 13 healthy males aged between 19 and 23. The side-lying patients were subject to TESCS at the T11/T12 level for twenty minutes. The maximum plantar flexion force of the foot with simultaneous recording of the electromyoelectrical activity (EMG), M-responses, and lower leg muscle responses evoked by a single spinal cord electrical stimulation (MEP) were recorded before and after long-term TESCS. Results. It was found out that 20 minute TESCS increased m. gastrocnemius strength. This was confirmed by 13.67 % increase of maximum torque and increases of m. gastrocnemius electrical activity during plantar flexion of the foot and its MEP amplitude. Conclusion. Long-term transcutaneous spinal cord stimulation can be used as an additional athletic training technique which effects the motor system of sportsmen participating in such kinds of sports, where the results depend on their strength.