Effect of Eight Weeks of Resistance Training on PAX7 and MyoD in Fast and Slow-Twitch Skeletal Muscles of Old Rats

Box 7 protein (PAX7) and myogenic differentiation (MyoD) proteins are the essential proteins to regulate the satellite cell and muscle hypertrophy.

We aimed to investigate the effect of resistance training (RT) on PAX7 and MyoD in soleus and extensor digitorum longus (EDL) muscles of old rats.

In this experimental study, 12 old female rats were randomly divided into two groups including RT and control groups. The RT program was three days a week for eight weeks, in which the rats climbed a one-meter vertical ladder with 26 steps. The carried weights varied from 50% of body weight in the first week to 100% of body weight in the 8th week. Kolmogorov- Smirnov test and independent sample t test was used for statistical analysis (P≤0.05).

MyoD protein in RT group significantly increased in soleus and EDL muscles compared with the control group (P=0.001). Also, Pax7 significantly increased in the soleus muscle in the RT group compared with control group (P=0.002); nevertheless, there was no significant difference in Pax7 protein in the EDL muscle between the RT and control groups (P=0.10).

RT can lead to proliferation and renewal of satellite cells in the soleus and EDL muscles by increasing PAX7 and MyoD proteins.