In rats that were made to age faster with a chemical, both moderate steady‑state cardio and short bursts of intense exercise helped the heart work better and reduced scar tissue. The workouts also raised levels of the anti‑aging peptide humanin and its partner IGF‑1 in the heart and blood, suggesting exercise can boost this pathway.

<b>Introduction:</b> Humanin, a mitochondrial-derived peptide, decreases in the elderly. This study evaluated the effects of concurrent moderate-intensity endurance training (MIET) or high-intensity interval training (HIIT) with D-galactose injection on cardiac function, and the serum and heart levels of humanin and IGF-1 in Wistar male rats. <b>Methods:</b> Left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure (LVEDP), &#xb1;maxdp/dt, contractility index (CI) and, Tau were monitored by PowerLab system in CTL, CTL&#x2009;+&#x2009;MIET, CTL&#x2009;+&#x2009;HIIT, D-gal, D-gal&#x2009;+&#x2009;MIET, and D-gal&#x2009;+&#x2009;HIIT groups. The histopathological score, fibrosis, and humanin and IGF-1 levels were measured with hematoxylin &amp; eosin, Masson's trichrome, and enzyme-linked immunosorbent assay, respectively. <b>Results:</b> Histopathological score and heart fibrosis were reduced by HIIT and MIET in the D-gal group. LVSP, &#xb1;maxdp/dt, and CI were lower, while LVEDP and Tau were higher in the D-gal group than in the CTL group. MIET and HIIT alleviated the changes in LVSP, &#xb1;maxdp/dt, CI, LVEDP, and Tau. HIIT and MIET increased humanin levels in heart and serum of the D-gal group by modifying IGF-1 levels. <b>Conclusion:</b> The study suggests HIIT and MIET may improve cardiac function by regulating the IGF-1-humanin signaling pathway.