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 resistance exercise intensity and exercise-induced metabolic stress on the activation of anabolic signaling and expression of myogenic genes in skeletal muscle. METHODS: Ten strength-trained athletes performed high-intensity [HI, 74% of 1-repetition maximum (RM)], middle-intensity (MI, 54% 1RM), or middle-intensity (54% 1RM) no-relaxation exercise (MIR). Kinase phosphorylation 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 1/2Thr202/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. CONCLUSIONS: This study demonstrates that both intensity and exercise-induced metabolic stress can be manipulated to affect muscle anabolic signaling.

Exercise-induced expression of peroxisome proliferator-activated receptor γ coactivator-1α isoforms in skeletal muscle of endurance-trained males.

The aim of the present study was to investigate the effect of acute aerobic exercise on the expression of PGC-1α transcript variants in human skeletal muscle. Seven endurance-trained athletes performed a 90-min cycling test (62% of VO2max). At resting state, the levels of N-truncated (NT)-PGC-1α and PGC-1α exon 1a-derived transcripts were significantly higher (>20-fold; P<0.05) than those of PGC-1α exon 1b- and 1c-derived transcripts. Acute exercise did not change the PGC-1α exon 1a-derived expression level, but it did increase the expression level of NT-PGC-1α mRNAs 6-fold, and the expression levels of PGC-1α exon 1b- and 1c-derived mRNAs>200-fold (P<0.05). We conclude that NT-PGC-1α transcript expression in resting muscle and after acute moderate-intensity exercise constituted a significant share of total PGC-1α expression. The exercise led to a higher level of PGC-1α expression from alternative promoters (exon 1b- and 1c-derived mRNA) than from the canonical proximal promoter (exon 1a-derived mRNA).