Hepatoprotective effect of moderate-intensity continuous training against high-calorie diet-induced liver injury in a rat model

Nonalcoholic fatty liver disease (NAFLD) is a leading contributor to global liver‐related mortality. Moderate‐intensity continuous training (MICT) has shown promise in ameliorating hepatic steatosis and inflammation, but its effects on diet‐induced liver injury remain incompletely defined. This study aims to evaluate the histopathological hepatoprotective effects of MICT in female rats fed a high-calorie diet. Thirty female Wistar rats (8 weeks old; 100–200 g) were randomized into three groups (n = 10 each): standard diet (SD), high-calorie diet (HCD; 0.013 g/g bw glucose solution), and HCD plus MICT (HCD+MICT). MICT consisted of swimming five days per week for four weeks, with progressive durations (10–30 min) and 6% body weight loads. Body weight was measured pre and post intervention. Twenty-four hours after the final session, livers were collected for hematoxylin–eosin staining. Inflammatory cell infiltration and pyknosis/apoptotic bodies were quantified by blinded observers using ImageJ. Nonparametric analyses (Kruskal–Wallis with Dunn’s post hoc) and mixed effects ANOVA were applied. Fourteen rats completed the protocol (SD n=4; HCD n=5; HCD+MICT n=5). Only the HCD group exhibited significant weight gain (p = 0.0009). Median inflammatory cell counts were lower in HCD+MICT as compared with HCD (p = 0.048). Hepatocyte pyknosis/apoptotic bodies did not differ significantly between HCD and HCD+MICT (p > 0.05). No adverse events or exercise-related complications occurred. Four-week intervention of MICT attenuates hepatic inflammatory cell infiltration induced by HCD without significantly affecting hepatocyte apoptosis. These findings support MICT as a nonpharmacological strategy to reduce liver inflammation in high-calorie induced liver injury.