The effect of resistance-aerobic training on the growth of muscle fibers, serum testosterone and androgen receptors on soleus muscles, in different ages groups of male rats

The aim of this study was to evaluate the effect of aerobic resistance training on the growth of muscle fibers, testosterone and androgen receptors in male rats of different age groups. 30 male Wistar rats, child (n=10), young (n=10) and elderly (n=10), were divided into two groups of training and control Exercise were performed intermittently, one day for resistance and one day for aerobic for 6 weeks. 48 hours after the last training session, anesthesia, blood sampling and then were killed and then gastrocnemius and soleus muscles were extracted. Blood serum was also isolated and then blood testosterone was measured by ELISA, muscle growth was measured by light microscopy and gene expression of androgen receptors was measured using Real-time pcr. The results showed that the cross- sectional of muscle fiber in all three training groups of ages contains: child (p=0.001), young (p=0.003) and elderly (p=0.001) were more than control groups. There were no significant difference in serum testosterone between training and control groups of child (p=0.6), while serum testosterone in young (p=0.008) and elderly (p=0.001) training groups were more than controls. Also there were no significant difference in expression of androgen receptors between training and control groups of child (p=0.3), young (p=0.3) and elderly (p=0.8). The results showed that resistance-aerobic exercise can cause muscle hypertrophy at different ages by increasing testosterone concentration. Resistance-aerobic training can accelerate the growth process and also prevent muscle atrophy in old age.