High Intensity Interval Training Reducing Visceral Fat with Differential Activation of HSL Phosphorylation in Specific Site

Objective: To investigate the possible underlying mechanisms of why high-intensity interval training can significantly reduce the weight of visceral fat: differences in HSL (Hormone Sensitive Lipase) phosphorylation at different Sites (subcutaneous and visceral) .Methods: Female c57 bl/6 mice were fed a high-fat diet to produce a diet-induced obesity animal model. After successful modeling, 36 obese mice were randomly divided into high-fat diet control group (HFD group) , moderate-intensity continuous training group (MICT group) and high-intensity interval training group (HIIT group) .The HFD group was fed a high-fat diet for 12 weeks without exercise. The MICT group continued to exercise on a treadmill of approximately 60% VO₂ max with high-fat diet, while the HIIT group was given a high-intensity interval training of approximately 100% VO₂ max peak intensity with high-fat diet. At the end of the 12 weeks training, mouse body weight, Lee's index, inguinal (subcutaneous) and peri-uterine (visceral) fat weights were measured. Hepatocyte fat infiltration was observed by HE staining. Serum lipids (TC, TG, HDL-C, and LDL-C) were measured by colorimetry. HSL protein expression and phosphorylation of Ser563, ser565, ser660 were measured by Westernblot.Results: Compared with the HFD group as the baseline, there was a significant body weight decrease in the MICT group and HIIT group (P < 0.01) . HIIT and MICT showed no significant difference in subcutaneous fat reduction, but compared with MICT, HIIT could significantly reduce the peri-uterine (visceral) fat (P<0.01) ; Liver lipid droplet infiltration of HIIT group was lower than HFD and MICT, and LDL-C of HIIT significantly decreased (P<0.05) ; phosphorylation of ser563 in peri-uterine fat of HIIT was significantly higher than HFD and MICT (P<0.05) . Ser660 of inguinal fat was significantly higher in MICT than in HFD HIIT groups (P<0.05) .Conclusion: HIIT can reduce visceral fat, relieve hepatic fat lesions, and reduce LDL more than moderate-intensity continuous training. This is related to the fact that with HIIT training, the phosphorylation of HSL-ser563 rose specifically in visceral adipose tissue and fat hydrolysis was promoted.