Influence of exercise induced muscle injury on functional regeneration.

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In this studie was designed to correlate muscle injury following eccentric contraction with denervation and reinnervatin, and to examine the impact of nerve freezing on the neuromuscular system after temporary denervation. The great plasticity of muscle can well be demonstrated in the hypertrophy and the transformation by changed the neuronal control. On the other hand, muscle damage occurs after any form of eccentric contractions or high-intensity exercise. The muscle damage may lead to denervate by disruption of neuromuscular junction portion. The axonal sprouting and formation of new synapses were observed as a result of muscle damage. Therefore, regeneration of the injured muscle may significantly affect the changing of fibre type, and the marked degree of fibre type grouping and markedly smaller myofibers were observed in reinnervated muscle. The smaller myofibers may have normal functional properties, except for capability of hypertrophy regulation. On the otherhand, ischiadic nerve freezing resulted in total lack of neuromuscular transmission followed by a slow recovery. Muscle injury by muscle contusion with nerve freezing encouraged the early recovery. Immunochemical observations show that rapid and prominent upregulation of cytokines in motoneurons at initialstage of reinnervation is important for the regeneration of neuromuscular junction.