Epicardial Adipose Tissue Metabolic Changes Associated with Different Intensities Interval Exercise Preconditioning in Myocardial I/R Injury

Myocardial ischemia-reperfusion (I/R) injury remains a critical challenge in cardiovascular therapeutics, with exercise preconditioning emerging as a promising cardioprotective strategy. This study investigates the metabolic plasticity of epicardial adipose tissue (EAT)-a key paracrine regulator of myocardial injury-in response to graded intensities of interval exercise preconditioning during I/R injury. Male C57BL/6 mice underwent 6 weeks of low-, moderate-, or high-intensity interval treadmill training followed by I/R surgery. Untargeted metabolomics of EAT revealed intensity-dependent metabolic reprogramming. Moderate-intensity exercise preconditioning uniquely restored I/R-induced metabolic disturbances, reversing dysregulation in bile acid biosynthesis, xenobiotic detoxification, and cholesterol metabolism. In contrast, low- and high-intensity protocols incompletely normalized lipid homeostasis, with persistent suppression of glycerophospholipid metabolism and failure to rescue oxidative stress pathways (L + I/R vs. I/R, P = 0.01; H + I/R vs. I/R, P = 0.04). Multivariate analysis identified 51 overlapping metabolites in the moderate-intensity group showing full reversal of I/R-induced alterations, while the low- and high-intensity groups each showed partial recovery of 27 overlapping metabolites. Metabolic normalization by moderate-intensity exercise involved restoration of bile acid biosynthesis (I/R vs. SHAM: DA Score = -0.375, P = 0.001; M + I/R vs. I/R: DA Score = 0.25, P = 0.028) and xenobiotic detoxification (I/R vs. SHAM: DA Score = -0.4, P = 0.01; M + I/R vs. I/R: DA Score = 0.4, P = 0.01) pathways critical to mitochondrial function. These findings identify metabolic changes in EAT that are associated with exercise-induced cardioprotection, and indicate that moderate-intensity interval exercise is most strongly associated with restoration of EAT metabolic profiles after I/R. These associations warrant further mechanistic investigation to determine causality.