en Physical medicine Physical medicine پژوهشي Research <div style="text-align: justify;"><span style="font-size:9pt"><span minion="" pro="" style="font-family:"><b>Introduction</b>: The regenerative potential of cardiac stem and progenitor cells is affected by aging and detraining, with the C-Kit cardiac stem cell expressing the Nkx2.5 transcription factor playing a crucial role. Exercise is known to enhance organ regeneration during aging, but the mechanisms involved in new cardiomyocyte formation during physiological cardiac remodeling remain unclear.</span></span><br> <span style="font-size:9pt"><span minion="" pro="" style="font-family:"><b>Materials & Methods</b>: Eighteen aged Wistar rats (~440g) were divided into three groups: Control (CO), aerobic training (AT) (5 days per week, 50-75% of maximum speed) for six weeks, and detraining (DT) for four weeks. RT-PCR analysis determined Nkx2.5 gene expression, while immunohistochemical staining identified C-kit-positive and Ki67-positive cardiac progenitor cells.</span></span><br> <span style="font-size:9pt"><span minion="" pro="" style="font-family:"><b>Results</b>: In heart tissue, C-Kit and Ki67 values significantly differed between the control&ndash;training (P=0.001) and training-detraining (P=0.001) groups but not between the control and detraining groups for C-Kit (P=0.502) and Ki67 (P=0.475). Nkx2.5 exhibited a significant difference between control-training (P=0.001), training-detraining (P=0.001), and control-detraining (P=0.006).</span></span><br> <span style="font-size:9pt"><span minion="" pro="" style="font-family:"><b>Conclusion</b><b><span style="font-size:11.0pt"><span new="" roman="" style="font-family:" times="">: </span></span></b>Exercise increased the proliferation of heart stem cells, activating C-Kit differentiation and elevating Nkx2.5 expression, thereby delaying the effects of aging. However, detraining significantly impacted heart stem cell function, emphasizing the importance of sustained exercise for optimal cardiac health.<span lang="FA" dir="RTL" style="font-family:"Times New Roman",serif"></span></span></span></div> Physical activity, Aging process, Physical Deconditioning, Myocardial Regeneration, Stem Cells 9 17 http://jbrms.medilam.ac.ir/browse.php?a_code=A-10-687-1&slc_lang=en&sid=1 Arezoo Eskandari a.eskandari_1988@yahoo.com 10031947532846006907 10031947532846006907 Yes Department of Exercise Physiology, Faculty of Sport Sciences, Shahid Rajaee Teacher Training University, Tehran, Iran