TABLE 2.

Benefits of physical activity in nonalcoholic fatty liver disease (NAFLD) according to recent reviews, systematic reviews and meta-analyses

Author	Study	Country	Sample size	Intervention	Benefits
Magkos80	Review	USA	-	Habitual physical activity Exercise training with weight loss Exercise training without weight loss Detraining Resistance exercise	Variability in results. Increased cardiorespiratory fitness or reduced intra-abdominal obesity after training not necessarily accompanied by intrahepatic fat depletion33,85–89
Keating et al81	Systematic review and meta-analysis on 12 studies33,73,85,90,97	Australia	439 (241M, 177F, 21 N/R) Mean age 36–68 y	Variability in recruitment: obese, overweight, NAFLD, T2D and metabolic syndrome Aerobic exercise and/or progressive resistance straining Comparisons: exercise vs control or exercise + diet vs dietary interventions only 2–24 wk in duration and prescribed exercise on 2–6 d per wk. Intensities 45%−85% of VO2 peak or even less	Reduced liver fat by MRS or ultrasound or CT with minimal (1.4–2.2 Kg) or no weight loss. No effect of physical exercise on serum transaminase
Musso et al83	Systematic review and meta-analysis on 78 RCTs	Italy	38 RCTs NASH 40 RCTs NAFLD	Post-treatment histology 41% Glucose metabolism 71% Assessed cardiovascular risk factors 88% Lifestyle intervention, thiazolidinediones, metformin and antioxidants evaluated Five RCTs assessed moderate-intensity aerobic exercise alone in NAFLD33,55,73,97,98	Improved MRS-assessed steatosis and ALT levels Histology unchanged in 1 RCT55 Patients with NAFLD understand the benefits of exercise but lack confidence to perform it and are afraid of falling129
Orci et al84	Meta-analysis and Metaregression on 28 RCTs33,55,74,78,85,90,91,93,94–111	Switzerland	Patients with NAFLD or patients with obesity, T2D or metabolic syndrome (with established or likely NAFLD)	Exercise alone vs no exercise Exercise + diet vs diet Effect on intrahepatic lipid content, serum ALT and AST	Significant reduction in intrahepatic lipid content (MRS, CT, ultrasonography and histology), AST and ALT independently from dietary change Metaregression shows that individuals with increasing body mass index are more likely to benefit from the intervention No effect modification by variables related to the intensity of the intervention
Katsagoni et al82	Meta-analysis on 20 RCTs71,73,74,76,77,79,103,110–122	Greece	1073 exactly characterized NAFLD patients	Aerobic and resistance exercise (volume/intensity) and/or diet (moderate-carbohydrate vs low/moderate-fat diet) vs standard care Evaluation of liver enzymes, intrahepatic fat and liver histology, anthropometric and glucose metabolism parameters	Decreased liver fat (MRS or ultrasound) irrespectively of weight change Improved serum levels of liver enzymes (AST and ALT) Improved liver histology (estimated by NAFLD activity score) Continuous moderate-to-high volume MIT superior to continuous low-to-moderate-volume MIT or HIIT exercise protocols
Romero-Gomez et al61	Review	Spain	-	Discussion on role of physical activity in NAFLD Sedentary behaviour Physical activity Exercise	Exercise, without weight loss associated with a 20%−30% relative reduction in intrahepatic lipid Different forms of exercise (aerobic and resistance) equally effective Observed benefits upon exercising up to 12 mo but vanishing upon discontinuation Decreased de novo lipogenesis, increased VLDL mobilization, and improved peripheral insulin sensitivity Decreased visceral adipose tissue and lipid supply to the liver Improved cardiovascular function

ALT, alanine aminotransferase; AST, aspartate aminotransferase; CT, computed tomography; F, females; HIIT, high-intensity interval training; M, males; MIT, medium-intensity interval training; MRS, magnetic resonance spectroscopy; NAFLD, nonalcoholic fatty liver; NASH, nonalcoholic steatohepatitis; N/R not reported; RCT, randomized clinical trial; T2D, type 2 diabetes; VLDL, very low-density lipoprotein.