Mild exercise training favorably modulates gene expression in human skeletal muscle

Changes and plasticity in both gene expression and protein signaling in skeletal muscle is considered to be a major cause of metabolic syndrome, while it has been shown that mild exercise training at lactate threshold (LT) intensity is a safe and effective for prevention of metabolic syndrome. To elucidate the molecular mechanisms related to the beneficial effects of LT training for 60 min/day for 5 days/wk for 12 wk, we performed serial analysis of gene expression (SAGE) to examine global mRNA expression in human skeletal muscle. Approximately 57000 SAGE tags were analyzed for before training, as well as 5 days, 6 and 12 wk after the training. The LT training has coordinately induced many genes involved in mitochondrial energy metabolism, fat oxidation, glycolysis and creatine metabolism. Another molecular feature associated with this mild exercise regimen has been an induction of many genes encoding for potent antioxidant enzymes and molecular chaperons. Furthermore, the training modulated the expression levels of 233 novel transcripts. Thus, the current study reveals that LT exercise has favorably altered gene expression in human skeletal muscle to the prevention of metabolic syndrome. Keywords: transcriptome, serial analysis of gene expression, metabolic syndrome, exercise training, lactate threshold Healthy men performed cycle ergometer training at the lactate threshold level for 60 min/day, five days/wk for 12 wk. After subjects were fasted more than 12 h, muscle biopsies were obtained between 8:00 to 10:30 under local anesthesia with lidocaine from the middle portion of the right vastus lateralis. Muscle biopsies were performed before training, as well as at 5 days, 6 wk and 12 wk during the execution of the program. At 5 day, muscle biopsies were performed 1 h after the training session, since we expected that 4 times training from day 1 to 4 would augment the acute effects of the training at 5 day. To assess the sustained effect of the training program, muscle biopsies were performed 2 days after the last training session, at 6 and 12 wk. The muscle sample was quickly dissected from fat and connective tissues, immediately frozen with liquid nitrogen and stored at –80℃ until analysis.