INFLUENCE OF RESISTANCE EXERCISE INTENSITY AND METABOLIC STRESS ON ANABOLIC SIGNALING AND EXPRESSION OF MYOGENIC GENES IN SKELETAL MUSCLE

Introduction: We investigated the effect of resist- ance exercise intensity and exercise-induced metabolic stress on the activation of anabolic signaling and expression of myo- genic genes in skeletal muscle. Methods: Ten strength-trained athletes performed high-intensity (HI, 74% of 1-repetition maxi- mum (RM)), middle-intensity (MI, 54% 1RM), or middle-intensity (54% 1RM) no-relaxation exercise (MIR). Kinase phosphoryla- tion level and myogenic gene expression in muscle samples were evaluated before, 45 min, 5 h, and 20 h after exercise. Results: The lactate concentration in MI was approximately 2- fold lower than in the 2 other sessions, and was highest in MIR. The phosphorylation level of extracellular kinase 1/2 Thr202/Tyr204 after exercise was related to metabolic stress. Metabolic stress induced a decrease in myostatin mRNA expression, whereas mechano-growth factor mRNA level depended on exercise intensity. Conclusion: This study demonstrates that both inten- sity and exercise-induced metabolic stress can be manipulated to affect muscle anabolic signaling. Muscle Nerve 000:000-000, 2014