ObjectiveTo study the effects of Epimedii Folium polysaccharides on mice with exercise-induced fatigue and explore its possible mechanism of action. MethodICR male mice screened by swimming training were randomly divided into a control group， model group， vitamin C group， and low， medium， and high dose groups of Epimedii Folium polysaccharides， with eight mice in each group. The exercise-induced fatigue model was established by weight-bearing swimming training in each group except for the control group. After two weeks of weight-bearing swimming， the Epimedii Folium polysaccharide groups were given 100， 200， 400 mg∙kg^-1 of Epimedii Folium polysaccharides by gavage， and the vitamin C group was given 200 mg∙kg^-1 of vitamin C by gavage. The control group and the model group were given equal amounts of saline for 14 d. At the end of the experimental period， the body mass of the mice in each group and the time of last swimming due to exhaustion were recorded. Serum urea nitrogen （BUN）， lactic acid （LA）， lactate dehydrogenase （LDH）， malondialdehyde （MDA）， superoxide dismutase （SOD）， glutathione peroxidation （GSH-Px）， myoglycogen （MG） in skeletal muscle， hepatic glycogen （HG） in the liver were detected by kits. Hematoxylin-eosin （HE） staining was used to observe the pathological changes in muscle tissue. Western blot was used to detect the protein expression of p38 mitogen-activated protein kinase （p38 MAPK）， phosphorylation （p）-p38 MAPK， extracellular signal-regulated kinase1/2 （ERK1/2）， nuclear factor-κB （NF-κB）， p-NF-κB， interleukin-1β （IL-1β）， and interleukin-6 （IL-6） in muscle tissue. The immunofluorescence （IF） method was used to detect the expression of tumor necrosis factor-α （TNF-α） in skeletal muscle tissue of mice in each group. ResultCompared with the control group， the body mass of mice in the model group decreased， and the time of last swimming due to exhaustion decreased （P<0.01）. In addition， there were significantly higher serum levels of the fatigue metabolites LA， LDH， BUN， and lipid peroxidation product MDA （P<0.01） and decreased levels of MG， HG， SOD， and GSH-Px （P<0.01）. The protein expressions of p-p38 MAPK， ERK1/2， p-NF-κB， IL-1β， IL-6， and TNF-α in skeletal muscle tissue were significantly higher than those of the control group （P<0.01）. Compared with the model group， the body mass and time of last swimming due to exhaustion of the mice in the low， medium， and high dose groups of Epimedii Folium polysaccharides and the vitamin C group were increased （P<0.05， P<0.01）， and the contents of LA， LDH， BUN， and MDA were significantly decreased （P<0.05， P<0.01）. The levels of MG， HG， SOD， and GSH-Px increased （P<0.05， P<0.01）， and the protein expression levels of p-p38 MAPK， ERK， p-NF-κB， IL-1β， IL-6， and TNF-α in skeletal muscle tissue decreased （P<0.05， P<0.01）. ConclusionEpimedii Folium polysaccharides can play a role in alleviating exercise-induced fatigue by inhibiting the p38 MARK/NF-κB signaling pathway， thereby reducing the accumulation of metabolites， improving the activity of antioxidant enzymes， increasing the glycogen content of the body， and reducing inflammation in skeletal muscle.