| With athletics developing rapidly, in training and competitions, athletes carry more and more static load in longer and longer time so that skeletal muscle injury causing by static load increased in many projects such as shooting, archery, playing chess as and Wushu. The injury directly counteracts daily training and competition and restricts to maintain and develop exercise skills, even shortens exercise career. What is more, as social life gets more mechanized, automatic, professional and applying more computers, people keep some pose for longer and longer time at work, school and living. Then relational chronic skeletal muscles injuries causing by static load stand out and seriously impede people's daily life, study, work and adolescents growth and development. At present, exact mechanism of skeletal muscles injury causing by static load is uncertain. Hereby, this research discusses and analyzes systemically about not only mechanism of skeletal muscles injury causing by static load, but changes, actions and the relationship with injury time of endogenesis growth factor in repairing course. The research set up an animal model of skeletal muscles injury causing by static load so as to study skeletal muscle from energy metabolizing, Ca2+ homeostasis in cells, free radical, lipid peroxidation and endogenesis growth factors.At the animal experiment, we invented a rat static training flat. SD male rats of 8 weeks old stood on the flat with load on their back limbs. The load weighs half of the rat's avoirdupois. Each training lasted one hour in every morning and afternoon. Experiment courses were 3 days, 1 week, 2 weeks, 3 weeks and 4 weeks. The main results of this research are as followings:(1) Rats standing statically, carrying load for 3days to 4 weeks, will lead to skeletal muscle injury. The model is suitable to study skeletal muscles injury causing by static load. It does better that muscle-fibrin collecting mode and muscles working characters correspond to natural condition, less subjoin factors impact and the movement can be repeated.(2) Continuous static load for long time is not an adaptive load to economy. Continuous static load with the same intensity and load amount will cumulatively damage microstructure of skeletal muscle. Observing in general histology, where connecting with perimysium muscle fibre nucleuses increase and muscle fibre denaturalization is familiar. It suggests that continuousmuscle tension may be an important factor to muscle fibre injury when static load acts on skeletal muscle for a long time.( 3 ) CK and LDH in serum are indexes to estimate muscle injury causing by static load.(4) During the course of skeletal muscle injury causing by static load, content of the rats muscle-hepatin decrease, but not exhaust. There were no phenomena of lacking of material or compounding obstacle leading to decrease the content of ATP in muscle cells. It shows it does not lead to skeletal muscles injurys causing by static load that muscle cells exhaust of energy substance and lack of energy supplement.(5) During the course of skeletal muscle injury causing by static load, though there appears abnormal increase of Ca2+ in cytoplasm, SR and Mit, incepting capability of Ca2+ in SR and Mit does not depress. It suggests that the main reason for Ca2+ incremental abnormally in muscle cells is Ca2+ entad flowing evocated by membrane injury and permeability augment of muscle cells. Ca2+ overload in Mit did not lead to obstruct oxidative phosphorylation or fall Ca2+ regulating ability. So centrifugal exercise injury is different from centripetal ones that it is not Ca2+ overload in Mit that is centrum mechanism causing injurys of static load.( 6 ) LA content increases obviously in both cytoplasm and blood. LA changes in cytoplasm go together with skeletal muscle injury changes caused by static load. Mean while, increasing trend of LA content in cytoplasm is familiar with increasing trend of Ca2+ content in cytoplasm, SR and Mit as obviously positive correlation. It shows side...
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