Effects Of Different Intensity Exercise On The Rat's Skeletal Muscle Fiber Type

Object:The objective of this study was to investigate the percent of all kinds of muscle fibers change situation on SOL and TA in SD rats to different intensity exercise. Expecting to finding whether exercise leads muscle fiber transforming.Method:40 male adult Sprague-Dawley rats were randomly divided into four groups:Control(C,n=10),light exercise (LE,n=10), Moderate exercise(ME,n=10) and high exercise (HE,m=10).training by treadmill running(LE:19m/min x60min,ME:26m/min×44min,HE:34m/min x34min which by Sun xiao-juan created)for eight weeks, The exercise groups total distance equal to each. Control group and movement group rats were killed by separately after peaceful condition and movement latter 24 hours. Takes right side of rats hind legs soleus muscle and tibial muscle. The typeⅠmuscle fibers and typeⅡmuscle fibers were distinguished through ATPase coloration and isoforms of MHC were separated into MHCI,MHCⅡa, MHCⅡb and MHCⅡx through SDS-PAGE electrophoresis.Results:1) After different intensity exercise,compares with C group, The rats weight reduced in exercise group (P<0.05).2) TheⅠmuscle type's superficial density increased (P<0.01),theⅡ muscle type's superficial density reduced by light exercise (P< 0.05)3) After medium intensity exercise, TheⅡmuscle type's superficial density reduced, theⅡmuscle type's superficial density increased (P<0.05)4) After medium intensity exercise,TheⅠmuscle type's number density reduced (P<0.05),theⅡmuscle type's number density increased in anterior tibial (P<0.01).5) Compares with C group,The muscle type's MHCI% increased, the muscle type's MHCIIb% reduced afer low intensity exercise(P< 0.01),After medium intensity exercise, the muscle type's MHCIIb% and MHCI% reduced, the muscle type's MHCIIa% increased (P<0.01),Through high intensity exercise, The muscle type's MHCⅡx% increased in Soleus (P<0.01),the muscle type's MHCⅡa% increased in anterior tibial (P<0.05).Conclusion:1) Low, medium and high intensity exercise which can effectively SD rat's weight, exercise quantity is the key factor.2) After Low, medium and high intensity exercise, SD rat's muscle fibers number density and the superficial density had changes, Especially the superficial density is more significant change.3) Different exercise intensity can cause MHC subtype change, low intensity exercise MHCⅡb caused to MHCⅡx, MHCⅡa, MHCⅠ, Medium strength, high intensity exercise caused muscle type transformation from MHCⅠand MHCⅡb to MHCⅡx and MHCⅡa.