Associations of physical activity and fitness with hepatic steatosis, liver enzymes, and insulin resistance in children with overweight/obesity

Background Non-alcoholic fatty liver disease is the most common liver disease in childhood and is related to insulin resistance and cardiometabolic risk factors. Evidence supporting the association of fitness and physical activity with hepatic fat, liver enzymes, or triglyceride-to-high-density lipoprotein ratio is scarce in children. Objective To analyze the associations of physical fitness and physical activity (PA) with percentage hepatic fat, liver enzymes, insulin resistance, and cardiometabolic risk in children with overweight/obesity. Subjects A total of 115 children (10.6 ± 1.1 years; 54% girls) with overweight/obesity of the EFIGRO study (ClinicalTrials.gov: NCT02258126) were included in the analyses. Methods Cardiorespiratory fitness (CRF), musculoskeletal fitness and speed-agility were measured by the Alpha-fitness tests, and PA by wGT3X-BT accelerometers. Percentage hepatic fat was assessed by magnetic resonance imaging. Alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), aspartate aminotransferase (AST), insulin, glucose, triglycerides (TG), and high-density lipoprotein (HDL) levels were obtained from fasting blood samples. The homeostasis model assessment insulin resistance (HOMA-IR) and AST/ALT and TG/HDL ratios were calculated. Results Higher CRF was associated with lower percentage hepatic fat (β = −0.266, P = .01) and GGT (β = −0.315, P < .01), and higher AST/ALT ratio (β = 0.306, P < .01). CRF-fit children have lower GGT levels (15 ± 1 vs 17 ± 1 U/L, CRF-fit vs CRF-unfit children, P = .02), HOMA-IR (2.2 ± 0.1 vs 2.9 ± 0.1, P < .01) and TG/HDL ratio (1.4 ± 0.1 vs 1.9 ± 0.1, P = .01) and higher AST/ALT ratio (1.3 ± 0.0 vs 1.2 ± 0.0, P = .03), than CRF-unfit children. Conclusions These findings emphasize the importance of considering the improvement of CRF as a target of programs for preventing hepatic steatosis, type 2 diabetes and cardiovascular diseases in children with overweight.