The impact of exercise training on liver enzymes and liver fat content in adults with NAFLD: A systematic review and meta-analysis

Non-alcoholic fatty liver disease (NAFLD) is a pathological syndrome associated with increased serum levels of liver enzymes. The purpose of this study was to investigate the impact of exercise training on liver enzymes (ALT, AST, and GGT) and liver fat content in adults with NAFLD.

The PubMed, Web of Science, SID, Magiran, and Google scholar databases were searched until February 2022 for English and Persian articles. Meta-analyses were performed to compare the impact of exercise training on liver function in patients with fatty liver. SMD and 95% confidence interval (95% CI) were calculated using effect models. Also, the I2 test was used to determine heterogeneity, and the Funnel plot and Egger tests at a significant level of 0.1 were used to determine publication bias.

The results of meta-analysis of 36 studies with 1602 patient with NAFLD, showed that exercise training caused a significant decrease in ALT enzyme [SMD=-0.73, (95% CI: -0.51 to -0.95), p=0.001], AST enzyme [SMD=-0.61, (95% CI: -0.39 to -0.83), p=0.001], GTT enzyme [SMD=-0.66, (95% CI: -0.18 to -1.14), p =0.007], and intrahepatic fat [SMD=-0.58, (95% CI: -0.78 to -0.38), p=0.001].

The findings of the present meta-analysis show the important role of exercise training (aerobic, resistance, and combined training) in improving liver function. So, all three types of aerobic, resistance, and combined exercise are suggested as a non-drug approach to reduce liver enzymes and intrahepatic fat for adults with NAFLD.