Effect of Resistance Exercise Intensity on the Expression of PGC-1α Isoforms and the Anabolic and Catabolic Signaling Mediators, IGF-1 and Myostatin, in Human Skeletal Muscle

The purpose of this study was to investigate the acute mRNA expression of the peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) isoforms, insulin-like growth factor-1Ea (IGF-1Ea), and myostatin in response to two resistance exercise intensities. In a uniform-balanced, cross-over design, ten participants performed two separate testing sessions involving a lower-body resistance exercise component consisting of a lower-intensity (50% of 1-repetition maximum; 1-RM) protocol and a higher-intensity (80% of 1-RM) protocol of equal volumes. Muscle samples were obtained at before exercise (PRE), 45 minutes, 3 hours, 24 hours, and 48 hours post-exercise. Resistance exercise did not alter total PGC-1α mRNA expression; however, distinct responses of each PGC-1α isoform were observed. The response of each isoform was consistent between sessions suggesting no effect of resistance exercise intensity on the complex transcriptional expression of the PGC-1α gene. IGF-1Ea mRNA expression significantly increased following the higher-intensity session compared with pre-exercise and the lower-intensity session. Myostatin mRNA expression was significantly reduced compared with pre-exercise values at all time points with no difference between exercise intensity. Further research is needed to determine the effects of the various isoforms of PGC-1α in human skeletal muscle on the translational level as well as their relation to the expression of IGF-1 and myostatin.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author