Exercise training reduces intrahepatic lipid content in people with and people without nonalcoholic fatty liver

Abstract

Exercise training reduces intrahepatic lipid (IHL) content in people with elevated liver fat content. It is unclear, however, whether exercise training reduces IHL content in people with normal liver fat content. Here, we measured the effect of exercise training on IHL content in people with and people without nonalcohol fatty liver. We further measured changes in insulin sensitivity and hepatic energy metabolism. Eleven males with nonalcoholic fatty liver (NAFL) and 11 body mass index-matched individuals without nonalcoholic fatty liver (CON) completed a 12-wk supervised exercise training program. IHL content (proton(V magnetic resonance spectroscopy), maximal oxidative capacity O2max , spiroergometry), total muscle strength, body composition, insulin sensitivity (hyperinsulinemic-euglycemic clamp), hepatic ATP-to-total phosphorus ratio, and the hepatic phosphomonoester-to-phosphodiester (PME/PDE) ratio (phosphorus magnetic resonance spectroscopy) were determined. IHL content reduced with exercise training (P = 0.014) in the whole study population. The relative reduction in IHL content was comparable in NAFL (-34.5V ± 54.0%) and CON (-28.3 ± 60.1%) individuals (P = 0.800). O2max (P < 0.001), total muscle strength (P < 0.001), and skeletal muscle insulin sensitivity (P = 0.004) increased, whereas adipose tissue (P = 0.246) and hepatic (P = 0.086) insulin sensitivity did not increase significantly. Hepatic ATP-to-total phosphorus ratio (P = 0.987) and PME/PDE ratio (P = 0.792) did not change. Changes in IHL content correlated with changes in body weight (r = 0.451, P = 0.035) and changes in hepatic PME/PDE ratio (r = 0.569, P = 0.019). In conclusion, exercise training reduced intrahepatic lipid content in people with nonalcoholic fatty liver and in people with normal intrahepatic lipid content, and the percent reduction in intrahepatic lipid content was similar in both groups.