Energy-matched moderate and high intensity exercise training improves nonalcoholic fatty liver disease risk independent of changes in body mass or abdominal adiposity - A randomized trial

Background and Purpose. Exercise training is commonly prescribed for individuals diagnosed with nonalcoholic fatty liver disease (NAFLD); however, consensus regarding the volume and intensity of exercise for optimal benefits is lacking. Thus, we determined whether high intensity interval exercise training (HIIT) produced greater reductions in intrahepatic lipid (IHL) content and NAFLD risk factors compared with energy-matched moderate intensity continuous exercise training (MICT) in obese adults with liver steatosis. Methods. Eighteen obese adults were randomized to either 4 weeks of HIIT (4 min 80% VO(2)peak/3 min, 50% VO(2)peak) or MICT (55% VO2 peak, similar to 60 min), matched for energy expenditure (similar to 400 kcal/session) and compared to five non-exercising age-matched control subjects. IHL was measured by H-1-MRS and frequent blood samples were analyzed for glucose, insulin, c-peptide, and NEFA levels during a liquid meal test (180 min) to characterize metabolic phenotype. Results. Baseline body weight, visceral abdominal adiposity, and fasting insulin concentrations were greater in the MICT vs HIIT group (P < 0.05), while IHL was tightly matched between MICT and HIIT subjects (P > 0.05), albeit higher than control subjects (P < 0.01). Visceral abdominal adiposity, body mass, liver aminotransferases (ALT, AST), and hepatic apoptotic/inflammatory markers (cytokeratin 18 and fetuin a) were not reduced with either exercise training intervention (P > 0.05). Both HIIT and MICT lowered IHL (HIIT, -37.0 +/- 12.4%; MICT,-20.1 +/- 6.6%, P < 0.05); however, the reduction in IHL was not statistically different between exercise intensities (P = 0.25). Furthermore, exercise training decreased postprandial insulin, c-peptide, and lipid peroxidation levels (iAUC, P < 0.05). Conclusions. Collectively, these findings indicate that energy-matched high intensity and moderate intensity exercise are effective at decreasing IHL and NAFLD risk that is not contingent upon reductions in abdominal adiposity or body mass. (C) 2017 Elsevier Inc. All rights reserved.