Vesnu Publications (Farzanegan Radandish) Journal of Exercise & Organ Cross Talk 2783-2074 5 2 2025 06 30 Six-week combined exercise modulates mitochondrial dynamics (MFN1/DRP1) and oxidative stress (MDA/SOD) in fast- and slow-twitch muscles of aged rats 67 74 228071 10.22122/jeoct.2025.541565.1165 EN Sina Gholaminezhad Kolachahi Department of Exercise Physiology, University Campus2, University of Guilan, Rasht, Guilan, Iran. 0000-0003-3400-9372 Farhad Rahmani-nia Professor of Exercise Physiology, Faculty of Physical Education and Sport Sciences, University of Guilan, Rasht, Iran. 0000-0001-7021-0060 Mohammad Reza Fadaei Chafy Department of Physical Education and Sport Science, Ra.C., Islamic Azad University, Rasht, Iran. 0000-0003-0265-5329 Journal Article 2025 03 16 Aging is associated with mitochondrial dysfunction, which leads to decreased cellular function and the development of age-related diseases. Exercise training is considered one of the most effective strategies for improving muscle cell function. The aim of the present study was to investigate the effect of six-week combined exercise on mitochondrial dynamics and biogenesis markers (MFN1, DRP1) as well as oxidative stress markers (MDA and SOD) in fast- and slow-twitch muscles of aged rats. In this study, 16 male Wistar rats (463.2 ± 9.3 g) were randomly divided into two groups (n=8 per group): control and resistance-endurance training. The training group underwent combined resistance-endurance training, 6 days a week for 6 weeks (3 resistance days, 3 endurance days). Forty-eight hours after the last training session, animals were sacrificed and fast-twitch (gastrocnemius) and slow-twitch (soleus) muscle tissues were collected. Gene expression levels of mitofusin 1 (MFN1), dynamin-related protein 1 (DRP1) were measured by real-time PCR (RT-PCR). In slow-twitch muscle, exercise training significantly increased mRNA expression levels of SOD genes, and significantly decreased mRNA expression of DRP1 and the concentration of MDA compared to the control group (p<0.05). Similarly, in fast-twitch muscle, six weeks of combined training significantly increased SOD gene expressions and decreased DRP1 mRNA and MDA levels compared to controls (p<0.05). Combined exercise training positively modulates mitochondrial biogenesis and dynamics markers (decreased DRP1 mRNA) and enhances antioxidant capacity (increased SOD gene expression and enzyme activity, decreased MDA levels) in both fast- and slow-twitch muscles of aged rats, highlighting its significant role in mitigating age-associated mitochondrial dysfunction. These findings reflect improvements in markers of mitochondrial quality control and oxidative stress rather than direct measurements of mitochondrial function. https://www.jeoct.com/article_228071_0917c0a4aab07059f6f12cb44145ec30.pdf