Rats running with an incrementalintensity to exhaustion were used as an experimental model to investigate the effect of acute exhaustive exercise on inner-mitochondrial membrane of skeletal muscler. It was found that, in exhausted rats, fluorescence polarization and membrane microviscosity of inner mitochondrial membrane increased significantly and the activities of NADH-CoQ reductase and ATPase in respiratory chain declined by 34.2% and 46.2 %,respectively. The result suggested that the functional alterations in mitochondrial membranes such as the changes on membrane dynamic and activities of respiratory chain enzyme may be one of membrane molecular characteristics for exercise induced fatigue.