Effect of a Single Session of Intense Resistance Exercise with Glutamine Supplementation on the Relative Expression of Alpha and IIX Isoforms of Fast-Twitch Myosin Heavy Chain Gene in Male Rats

Neural, hormonal, and mechanical factors regulate the expression of fast-twitch isoforms in developing and mature muscle fibers. The transcriptional mechanisms responsible for regulating the gene expression of myosin heavy chain types are not well understood. This study aimed to determine the effect of a single session of intense resistance exercise with glutamine supplementation on the relative expression of the alpha and IIX isoforms of the myosin heavy chain gene in male rats.

This experimental study was conducted on 30 adult male Wistar rats divided into three groups: control, intense resistance exercise (first experimental group), and fierce resistance exercise combined with glutamine supplementation (second experimental group). The exercise groups participated in a single session of resistance climbing on an inclined plane with 4 sets of 5 repetitions, 30 seconds of rest between repetitions, and 2 minutes of rest between sets. Glutamine supplement powder was dissolved in 100 ml of distilled water at a dose of 0.5 grams per kilogram of body weight and administered daily via gavage for 5 days. The expression of alpha and IIX isoforms of the myosin heavy chain gene was examined in the extensor digitorum longus muscle tissue.

The relative expression of the alpha myosin heavy chain gene in the fast-twitch muscle fibers increased significantly in the first experimental group (1.93±0.298) and the second experimental group (1.65±0.195) compared to the control group (P<0.05). The relative expression of the IIX motor unit gene in the fast-twitch muscle fibers also increased significantly in the first experimental group (1.42±0.239) and the second experimental group (1.26±0.190) compared to the control group (P<0.05). The increase in the relative expression of the alpha myosin heavy chain gene in the first experimental group compared to the second experimental group was statistically significant (P<0.05). However, the increase in the relative expression of the IIX motor unit gene in the first experimental group compared to the second experimental group was not statistically significant.

Our study concludes that a single session of intense resistance exercise, with or without glutamine supplementation, significantly increases the relative expression of the alpha myosin heavy chain gene and the IIX motor unit gene in the fast-twitch muscle fibers of the extensor digitorum longus muscle in adult male rats. These findings provide valuable insights into the molecular