Abstract: Purpose: The purpose of the research is to discuss the effect of gavaging astaxanthin combined with quantitative load swimming training on antioxidant capacity in rats' skeletal muscle. Methods;32 healthy male SD rats of 7 weeks old are selected and fed adaptively for three days and divided into 4 groups randomly: control group(C), exercise group(T), medication group(M)and exercise medicine-taking group(TM). The exercise group and exercise medicine-taking group undergo progressive load swimming exercise for 6 weeks, The treated group and the control group were gavaged natural astaxanthin daily, a dose of 400mg/kg. Detection of rat blood Creatine kinase , lactate dehydrogenase content, skeletal muscle tissue superoxide dismutase, malondialdehyde, glutathione peroxidase, catalase content is conducted after 6 weeks swimming exercise. Results: long-term increasing load training significantly increases rats' serum LDH (P < 0.01) and CK (P < 0.01) levels, while skeletal muscle SOD activity, SOD/MDA ratio, GSH-PX , T- AOC and CAT decrease significantly. Gavaging natural astaxanthin reduces serum LDH, CK concentration and skeletal muscle MDA content induced by long-term increasing load training, but at the same time significantly increases the skeletal muscle SOD activity, SOD/MDA ratio, GSH-PX, T- AOC and CAT. Conclusions: (1) long-term increasing load training damages the structure, function and integrity of the skeletal muscle cell membrane, which is mainly reflected in the increase of concentration of serum LDH and CK.(2) Gavaging natural astaxanthin reduces serum LDH , CK concentration and skeletal muscle MDA content induced by long-term increasing load training. The SOD activity in skeletal muscles, SOD/MDA ratio, GSH-PX, T- AOC and CAT increase significantly, which might be the mechanism of natural astaxanthin to protect the function and structural integrity of the cell membrane in movement skeletal muscles

Key words: natural astaxanthin, skeletal muscle, free radical metabolism, antioxidant