Abstract: BACKGROUND: Exercise induces the secretion of muscle factors, such as irisin, which regulates the browning process of white adipose tissue and may contribute to the treatment of obesity. Exercise-mediated browning effects are related to exercise intensity and high-intensity intermittent exercise is superior to moderate-intensity continuous training in inducing adipose tissue browning.
OBJECTIVE: To observe the effects of different exercise interventions on irisin, leptin, adiponectin and visceral fat in obese rats. 
METHODS: Fifty male SPF Sprague-Dawley rats were divided into normal control group (n=10) and obese model group (n=40). Changes in body mass were recorded for 10 weeks. Thirty rats with higher body mass were selected from the successful modeling rats and randomly divided into three groups (n=10 per group): obese quiet control group, obese moderate-intensity continuous exercise group and obese high-intensity intermittent exercise group. The two exercise groups were subjected to moderate-intensity continuous exercise or high-intensity intermittent exercise. The body mass, visceral fat, blood glucose, blood lipids, blood irisin, leptin and adiponectin levels in the obese rats were measured after different exercise interventions. 
RESULTS AND CONCLUSION: (1) The body mass of the rats in the obese model group increased significantly compared with that of the normal control group (P < 0.01). The final body mass of the high-intensity intermittent exercise group was significantly lower than that of the moderate-intensity continuous exercise group (P < 0.01). (2) The Lee’s index of the obese quiet control group was significantly higher than that of the normal control group (P < 0.01) and the Lee’s index of the high-intensity intermittent exercise group was significantly lower than that of the obese quiet control group (P < 0.01). However, there was no significant difference between the high-intensity intermittent exercise group and the normal control group (P > 0.05). (3) The fat content of the obese quiet control group was significantly higher than that of the normal control group, moderate-intensity continuous exercise group and high-intensity intermittent exercise group (all P < 0.01). (4) The results of serological analysis showed that fasting blood glucose in the obese quiet control group was significantly higher than that in the normal control group (P < 0.01). During high-fat feeding, the blood glucose level was significantly lower in the moderate-intensity continuous exercise group and high-intensity intermittent exercise group than the obese quiet control group (both P < 0.01). (5) Triglyceride, cholesterol and low-density lipoprotein levels in the obese quiet control group were significantly higher than those in the normal control group (all P < 0.01). Compared with the obese quiet control group, the moderate-intensity continuous exercise significantly decreased the levels of triglycerides, cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol (all P < 0.01), while the high-intensity intermittent exercise significantly downregulated the levels of triglycerides and high-density lipoprotein cholesterol (P < 0.05). (6) Serum irisin and adiponectin levels were significantly decreased and leptin level was significantly increased in the obese quiet control group (all P < 0.01), while serum irisin and leptin levels were significantly increased in the moderate-intensity continuous exercise group and high-intensity intermittent exercise group (all P < 0.01). (7) Triglycerides, leptin, and final body mass were positively correlated with total fat mass (r=0.959, 0.842, 0.923, all P < 0.01), and irisin and adiponectin levels were negatively correlated with total fat mass (r=-0.720, -0.669, both P < 0.01). (8) To conclude, high-fat diet could increase body mass and visceral fat, decrease serum irisin and adiponectin levels, and increase leptin level in rats. Exercise training could reduce visceral fat, improve blood glucose and lipid metabolism, regulate leptin and adiponectin levels, and increase serum irisin level in obese rats. Moreover, the high-intensity intermittent exercise has a better effect on fat loss in obese rats. 

Key words: high-intensity intermittent exercise, obesity, rat, irisin, leptin, adiponectin