Objective: The present thesis was to study the influence of living high-training low exercise on 3-methylhistidine of skeletal muscles and corticosterone of blood serum in rats through a rodent exercise protocol of hypoxic endurance, and to explore the correlation of living high-training low and skeletal muscular protein degradation.Methods: Male Sprague-Dawley rats (7 weeks old) were divided into 4 groups randomly: control group (NC), normal exercise group (NE), hypoxic group (HC) and living high-training low group (HE).The hypoxia circumstance was normal pressure hypoxia, oxygen concentration was 13.6%, it equivalently 3500 m above sea level.All the four groups were divided into five groups as 1 day, 3 day, 7 day, 14 day and 28 day group.The hypoxia time course were 20:00~06:00 everyday;the exercise groups performed treadmill exercise of 20 m/ min, 1 h/d.3-methylhistidine in skeletal muscles and corticosterone of blood serum were tested by HPLC and ELISA respectively.Results: (1)After 28 days, compared with NC group, NE, HC, HE gronps body weight decreased significantly (P<0.05, P<0.01, P<0.01).(2) After 14 days, endurance exercise,hypoxia and HiLo treatment inhibited the increase of the gastrocnemius muscle mass (P<0.05, P<0.01, P<0.05 respectively).And 28 days later, HC groups muscle mass is much less than those of NC and NE group (P<0.05).(3) After 3 days,exercise, hypoxia and HiLo promoted 3-MH level of the skeletal muscles significantly (P<0.05);after 28 days, NE,HE were higher than NC (P<0.05, P<0.01).(4) After 1 days treatment, the corticosterone levels in serum increased significantly under the condition of exercise, hypoxia and HiLo (P<0.05).And HE group were much higher than NC in the following 3 d, 7 d, 14 d and 28 d (P<0.01).(5) Both hypoxia and HiLo promoted the blood urea nitrogen after 1 days treatment (P<0.01);and the influence of HiLo were lasting in the following 3 d, 7 d, 14 d and 28 d (P<0.01).Conclusion: On the basis of these data, living high-training low could increase the amount of 3-MH in the skeletal muscles, and promote the secretion of corticosterone significantly.The study demonstrated that a relationship exists between the decrease of skeletal muscle mass and the increase of protein degradation in the condition of living high-training low.