Objective To observe the protective effect of Qihuo Yin on muscle tissue of rats after acute exhaustive exercise and its influence on behavioral changes,and to explore its anti-fatigue mechanism.Methods Eighteen male Sprague-Dawley rats were randomly divided into blank control group,model group and the Qihuo Yin group,with 6 rats in each group.Treadmill exercise was used to establish exhaustive exercise fatigue model of rats.The blank control group was given the same volume of normal saline by gavage once a day as the rats in the model group,and the rats in the Qihuo Yin group were given Qihuo Yin by gavage once a day; the course of treatment was 7 consecutive days for all groups.The blank control group were not given any training.The rats in the model group and the Qihuo Yin group were given treadmill training for 30 minutes（ 15-30 m/min） 30 minutes after gavage for 6 consecutive days,and on day7,they were given treadmill training with a speed of 30 m/min.Exhaustive exercise time was recorded for the rats in the model group and the Qihuo Yin,and the serum levels of creatine kinase（ CK）,lactate dehydrogenase（ LDH）,lactic acid（ LA）,urea nitrogen（ BUN） were measure.At the same time,the behavioral changes of rats were observed.Results Compared with the blank control group,the levels of serum LDH,LA,CK,BUN in the model group were significantly higher than those in the blank control group（ P< 0.01）.Compared with the model group,the exhaustive exercise time of rats in Qihuo Yin group was significantly longer than that in the model group（ P < 0.01）,and the levels of serum LDH,LA,CK,BUN were significantly lower than those in the model group（ P <0.05）; there was no significant change in the incubation period of the rats rotating rod test animals in the Qihuo Yin group,but the activity latency of the total area of the autonomic activity reaction box was significantly prolonged（ P < 0.05）.Conclusion Qihuo Yin can significantly prolong the exhaustive exercise time of rats and have an effect on the autonomic activity of rats.It plays an anti-fatigue effect by reducing the production of various metabolites during exercise-induced fatigue in rats.