FOXO3 and familial dilated cardiomyopathy: Therefore, exercise promotes the binding of FGF21 to KLB on cardiomyocytes, subsequently activates AMPK-FOXO3 signaling, upregulates the mRNA expression of cardiac SIRT3, and reduces the hyperacetylation of myocardial mitochondrial enzymes to improve mitochondrial function, thus alleviating DCM-related heart damage.