(86) confirmed that exercise training increases the expression of fibroblast growth factor 21 (FGF21) protein, inhibits the activation of the TGF-β1-Smad2/3-MMP2/9 signaling pathway, and reduces collagen synthesis, ultimately alleviating cardiac fibrosis and improving cardiac dysfunction in mice after myocardial infarction. Here, MMP2 is linked to myocardial infarction.