High-intensity interval training has a greater effect on metabolic profiles than the dietary composition in male rats

Exercise and dietary factors play an important role in shaping the metabolic profile of skeletal muscle. This study compared the effects of 12 weeks of high-intensity interval training (HIIT) with a normal diet (ND) or a high-fat diet (HFD) on food and energy intake, as well as the metabolic profile of the gastrocnemius muscle in male rats. Thirty-two Wistar rats were assigned to four groups (n = 8): normal diet control (NDC), high-fat diet control (HFDC), HIIT+ND, and HIIT+HFD. Our findings demonstrated that HIIT decreased gastrocnemius muscle mass and the levels of beta-alanine, glycine, serine, tyrosine, and fructose 6-phosphate, while increasing glutamic acid levels. The HIIT+ND group exhibited significantly lower lactic acid levels than the other groups and lower threonine levels than the NDC and HFDC groups. Food and energy intake increased to a lesser extent in the HFDC and HIIT+HFD groups than in the ND and HIIT+ND groups. These findings indicate that HIIT exerts a predominant effect on metabolic regulation and can attenuate metabolic disturbances independently of diet. However, HIIT under a ND significantly affects certain glycolytic metabolites, including lactic acid.