| Abstrakt: |
The paper describes the possibility of selective activation of flexor and extensor muscle motor pools of lower extremities, thus controlling the running step coordination structure. The first part of our experiments revealed that the lowest activation threshold of extensor muscles was observed mainly when the spinal cord was stimulated at the L1–L2 vertebra level with a 5 mm offset from the spine midline, and in flexor muscles at the T11–T12 vertebra level with a 5 mm offset from the spine midline. In the second series of experiments, we studied the influence of coccygeal plexus rhythmic electrical stimulation on the parameters of motor evoked potentials (MEPs) in the thigh and lower leg muscles caused by a single electrical stimulation of the spinal cord at the T11–T12 vertebra level. A 10-s coccygeal plexus stimulation changed the studied muscles' motor pools excitability, which was manifested in MEP amplitude dynamics. The excitability of the motor pools of m. rectus femoris (RF) and m. tibialis anterior (TA) increased whereas for m. biceps femoris (BF) and m. gastrocnemius (GM), in contrast, decreased. The data on the spinal cord stimulation localization, characterized by the lowest threshold activation in lower extremity muscles, were used in studies on changing the coordination structure of the running step under selective and multi-segmental stimulation. Coccygeal plexus electrical stimulation increased the swing realization speed, decreased the foot support duration, as well as increased electromyographic (EMG) activity during the support phase in BF by 15.9% (p < 0.05) and in GM by 16.5% (p < 0.05). The running step duration remained unchanged, except for the foot support period. Multi-segmental spinal cord stimulation (T11–T12, during foot transfer, L1–L2, during foot support) increased EMG activity in the extensor muscles of m. vastus lateralis (VL) and GM during support by 59.59% and by 77.23%, respectively (p < 0.05). Flexor motor pools activation during the transfer period increased the activity of flexor muscles BF and TA. The multi-segmental stimulation effect (T11–T12, during the transfer period, L1–L2, during the support period and rhythmic electrical stimulation of the coccygeal plexus) increased the distance traveled by the anthropometric points in the swing phase, and also increased the upper tibia, lower tibia, and toe anthropometric points movement speed during the extremity transfer period. In the foot lowering and support phase, the EMG activity of TA and BF increased. [ABSTRACT FROM AUTHOR] |
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