An Acute Bout of Concurrent Exercise on Mechanotransducing Properties of the Skeletal Muscle Fiber

Aim: It was the aim of this study to extrapolate the affect which an acute bout of concurrent training, aerobic exercise coupled with resistance exercise, as compared to resistance exercise alone, has on the mechanically sensitive signaling proteins of the muscle fiber and their downstream signaling proteins as to give insight into the intracellular metabolic milieu. Methods: Eleven healthy males performed unilateral tricep extension exercise with both arms. One randomly designated arm took part in the concurrent training bout comprising an acute aerobic intervention shortly followed by resistance exercise. Biopsies were obtained from the M. Triceps Brachii at three time-points; Pre-RE, Post+15 RE, and post+3-hr RE. Tissue was then analyzed for mechanically sensitive proteins A7B1 Integrin, Yes-Associated Protein, Focal Adhesion Kinase, and downstream signaling proteins AMP-Kinase, p70s6k, and 4ebp1. Results: AMPK showed a significant carm X time interaction (p < 0.05). P70s6k showed no condition X time interaction. 4E-BP-1 showed a significant condition X time interaction (p< 0.05). Beta-1 Integrin showed a main effect of time increasing from time-point 1 to time-point 3 across both arms. FAK showed a main effect of time decreasing from time-point 1 to time-point 3 across both arms. YAP showed no condition X time interaction. Conclusions: Here we demonstrate the ability of the triceps brachaii to respond in a similar manner between concurrent exercise and resistance-only exercise concerning the skeletal muscle specific integrin isoform, alpha7 beta1. Moreover, we demonstrate the large decrease of 4E-BP1 and increase of AMPK immediately following the AE protocol along with possible augmentation of FAK through AMPK inhibitory mechanisms. This denotes the possibility that, as compared to past studies, the triceps brachaii uniquely responds and regulates intracellular remodeling mechanisms following an acute bout of concurrent exercise as compared to the lower body