Effects Of Excessive Centrifugal Training On PJPs Domain Of Skeletal Muscle And The Effect Of Acupuncture On Intervention

1. Objective: Overuse injuries are common muscle-skeletal disorders in both workplace and athletic environments and seriously interfered with the daily work and life in both athletes and ordinary workers. The research showed that the intervention of acupuncture could treat excessive eccentric exercise-induced overuse injury symptoms of skeletal muscle, but the mechanism is still not very clear. According to the new research, the effects of acupuncture may be related to the changes of PJPs domain(PJPs: perimysial junctional plates), which is formed by perimysial collagen network and endomysium and sarcolemma and subsarcolemma. In this study, overuse injuries’ animal models were adopted to study the effects of acupuncture intervention on excessive eccentric exercise-induced PJPs domain’s changes, and to explore the therapeutic mechanism of acupuncture.2. Methods: Thirty healthy male Wistar rats were randomly assigned to five groups, namely four weeks control group(4C), five weeks control group(5C), four weeks training group(4E), one week recovery group(1RG), one week recovery group with acupuncture intervention(1RAG).Control groups were allowed food and water ad libitum, other groups attended continuous excessive eccentric exercise for 4 weeks(incline-16°, speed 16-20 m·min-1, 60-90 min·d-1, 5 days per week). The extensor digitorum longus of 4C and 4E groups were removed 36 h after the end of the training, and no intervention in 5C and 1RG groups. Extensor digitorum longus of 1RAG were stuck with acupuncture needles in the recovery period for 4 min every time, meterials were drawn instantly after one week. The right sight side of extensor digitorum longus was observed by transmission electron microscopy and figuring out the perimysial collagen network’s structural changes of the left with scanning electron microscopy using or not using a digestion technique(Na OH).3. Results: 3.1 Excessive eccentric exercise leaded to skeletal muscle PJPs domain changes, specific changes were: 1) Subsacrolemmal changes were overcontracted sarcomere(P<0.001), and sarcomere structure damaged seriously, such as degradated myofibril, streaming Z-band and disappeared I-band. Intermyofibrial and subsarcolemmal mitochondria were swelling. 2) Sarcolemma degradated seriously, accounting for 54% of the total, and jagged form distribution, while the number of caveolae significant increasing(P<0.01). 3) The number of collagen plexi were increasing, but aparting from endomysium and sarolemma, reduced the number of PJPs(P<0.001). 3.2 Compared with 4E group, skeletal muscle PJPs domain changes in 1RG group were relieved, specific changes were: 1) Subsacrolemmal changes were the length of sarcomere increasing, and achieved 85.23% of C group. There ensued a partial restoration of sarcomere damage, such as Z-band tended to be normal, I-band with partial recovery. Intermyofibrial and subsarcolemmal mitochondria returned to normal. 2) The degree of sarcolemmal degradation significant decreased(P<0.001), while the number of caveolae significant increasing(P<0.05). 3) The number of collagen plexi attaching adjacent myofibers significant increased(P<0.001). 3.3 Compared with 1RG group, skeletal muscle PJPs domain changes in 1RAG group were reliefed significantly, specific changes were: 1) Subsacrolemmal changes were the length of sarcomere tending to be normal, and achieved 94.51% of C group. Sarcomere tended to be normal. The intermyofibrial mitochondrial fusion had risen considerably(P=0.09), and the subsarcolemmal mitochondrial fusion had risen significantly(P<0.001), and the number also showed a significant increase. 2) The number of caveolae significant decreased(P<0.001). 3) The number of collagen plexi attaching adjacent myofibers significant decreased(P<0.001).4. Conclusion: 4.1 Excessive eccentric training caused the collagen plexi aparting from endomysium and sarolemma, and reduced the number of PJPs. Therefore, PJPs domain’s homeostasis changed, followed by skeletal muscle overuse injuries. 4.2 The number of PJPs was increasing after 1 week of natural recovery, and prevented muscle damage repair process. 4.2 Acupuncture intervention caused a significant increase in the number of subsacrolemmal mitochondria, and protected sarcolemmal integrity, and promoted defective sarcolemma resealing. Ultimate effects were skeletal muscle’s ultrastructural changes recovering and overuse injuries relieving by adjusting PJPs domain functions.