FNDC5 and Myocardial fibrosis: Eight weeks of swimming exercise (60 min/day, five times/week for 8 weeks) activated the Sirt1/PGC-1 α/FNDC 5 signaling pathway through the inhibition of miR-34a expression, which promoted irisin secretion, reduced the expression of fibrosis markers (COL-1, COL-3, and TGF- β 1), and improved myocardial fibrosis in type 2 diabetic rats [119].