Effect of training intensity on nonalcoholic fatty liver disease

Background: Training intensity may play a key role in magnifying the protective effect of physical exercise against nonalcoholic fatty liver disease (NAFLD). Purpose: This study aimed to test the hypothesis that vigorousintensity and interval training is as effective as moderate-intensity and continuous exercise training on NAFLD in high-fat diet (HFD)-induced obese mice. Methods: C57BL/6 mice (N = 40) were fed a standard-chow diet (n = 10) or HFD (n = 30) for 16 wk. After the initial 8-wk dietary treatments, HFD mice were further divided into HFD only (n = 10), HFD plus vigorous-intensity and interval treadmill running (VIT) (n = 10), and HFD plus moderate-intensity and continuous treadmill running (MIT) (n = 10) for the remaining 8-wk period. Results: Chronic exposure to HFD resulted in hepatic steatosis in conjunction with an obese and impaired glucose tolerance condition characterized by dyslipidemia, hyperinsulinemia elevated markers for the liver damage, and hypoadiponectinemia. Although VIT and MIT alleviated the NAFLD conditions, the former was more effective at alleviating hepatic steatosis than the latter. The intensity-dependent benefit of exercise training against hepatic steatosis was associated with greater activation of VIT on hepatic AMP-mediated protein kinase in conjunction with greater suppressive effect of VIT on hypoadiponectinemia, downregulation of the Adiponectin receptor 2 signaling pathway, and upregulation of the NF-κB signaling pathway in the liver. Conclusions: The current findings suggest that VIT is an alternative way of exercise training to combat hepatic steatosis associated with an obese and impaired glucose tolerance phenotype.