The Response of skeletal muscle sarcomeric proteins to 8 week progressive resistance training in Sprague-Dawley rats

Alpha (α)-actinins are located in the skeletal muscle Z-line and form actin–actin cross-links. It belongs to a highly conserved family of actin-binding proteins – the spectrin superfamily, which also contains the spectrins and dystrophin. Mammalian skeletal muscle has two isoforms:α-actinin-2 and α -actinin-3. However, the response of a-actinin to exercise training is little understood. Forty female Sprague-Dawley rats at the age of three months were obtained from Razi institute and assigned to a control(C; n=18) or exercise training (T; n=22) group. This study examined the effects of 8 weeks of resistance training on muscle mass and α -actinin-2 and α -actinin-3 levels in the flexor hallucis longus muscle(FHL). The resistance training consisted of climbing (with 1-RM until exhaustion) a ladder carrying a load suspended from the tail. The weights were increased gradually throughout the 8 weeks of training. Following 8 weeks of training, we observed significant increase in absolute muscle mass in FHL (P=0.01). Results show that no significant difference was found in α -actinin-2 and α -actinins 3 expression levels between C and T animals in response to progressive resistance training (P=0.61 and P=0.19 respectively). Surprisingly, protein expression levels of α -actinin-2 decreased 12% and α -actinin-3 increased 13% following 8 week of resistance training between groups, but it wasnt statistically significant. The results of this study demonstrate that progressive resistance training do not alters the expression level of α-actinins at the cellular levels in skeletal muscle and probably further investigations will indicate sarcomeric protein's response to exercise training.