Fig 1: Low‐dose exercise upregulates cardiac C1q complement/tumor necrosis factor‐associated protein 9 (CTRP9) expression by increasing circulating insulin‐like growth factor 1 (IGF‐1). (A) Isolated cardiomyocytes were treated with serum samples from myocardial infarction (MI) mice with different doses of exercise intervention. (B) CTRP9 expression level in cardiomyocytes after treatment with serum from MI mice (n = 4) for quantitative real‐time polymerase chain reaction (qPCR) and n = 3 for western blotting. (C) Heatmap of serum proteomics of MI mice with low‐dose exercise (n = 3). (D) CTRP9 expression level in cardiomyocytes after treatment with IGF‐1 or hyaluronan binding protein 2 (HABP2) (n = 4). (E) Concentration of circulating IGF‐1 in MI mice post‐exercise (n = 6). (F) Concentration of circulating IGF‐1 in cardiac‐specific knockdown of CTRP9 mice post‐exercise (n = 6). (G) Concentration of circulating IGF‐1 in cardiac‐specific CTRP9 overexpression mice (n = 6). (H) Protocol for IGF‐1 supplementation in CTRP9 knockout (KO) mice with established MI. IGF‐1 was administered via intraperitoneal injection 4 weeks post‐surgery. (I) CTRP9 expression level in CTRP9 KO mice heart post‐exercise (n = 4). (J) Concentration of circulating IGF‐1 in CTRP9 KO mice after administration of IGF‐1 (n = 6). (K) Supplementation of IGF‐1 failed to improve cardiac function in CTRP9 KO mice (n = 8). (L and M) Cardiac infarct size (L) (n = 6) and heart weight to body weight ratio (M) (n = 8) in CTRP9 KO mice with IGF‐1 treatment. (N and O) Cardiac wheat germ agglutinin (WGA) staining (N) (n = 6) and Masson staining (O) (n = 6) in CTRP9 KO mice with IGF‐1 treatment. * p < 0.05, ** p < 0.01, *** p < 0.001.