Abstarct: Background: Physical exercise is considered one of the most effective non-pharmacological strategies for improving cellular health and delaying the aging process. However, the effects of different exercise intensities on aging-related biomarkers, particularly serum telomerase activity and sirtuin levels, remain unclear. Therefore, this study aimed to investigate the effects of different exercise intensities on serum telomerase activity and serum sirtuin levels in men. Methods: This quasi-experimental study employed a pretest–posttest design. Healthy male participants were voluntarily recruited and assigned to exercise programs with different intensities. Blood samples were collected before and after the intervention period. Serum telomerase activity and serum sirtuin levels were measured using the enzyme-lixnked immunosorbent assay (ELISA). Data were analyzed using appropriate statistical tests, and statistical significance was set at P < 0.05. Results: The findings indicated that different exercise intensities altered serum telomerase activity and serum sirtuin levels, with responses depending on exercise intensity. Overall, moderate- and high-intensity exercise produced more favorable effects than low-intensity exercise by increasing biomarkers associated with cellular health and healthy aging. Conclusion: Appropriate exercise intensity may improve cellular adaptations by enhancing telomerase activity and sirtuin levels, reducing oxidative stress and inflammation, and ultimately contributing to genomic stability and delayed cellular aging.