Co-ingestion of carbohydrate with branched-chain amino acids or l -leucine does not preferentially increase serum IGF-1 and expression of myogenic-related genes in response to a single bout of resistance exercise

The purpose of this study was to determine if the co-ingestion of carbohydrate (CHO) with branched-chain amino acids (BCAA) or l -leucine (LEU) preferentially affected serum IGF-1 and the expression of myogenic-related genes in response to resistance exercise (RE). Forty-one college-age males were randomly assigned to 1 of 4 groups: CHO, CHO-BCAA, CHO-LEU, or placebo (PLC). Resistance exercise consisted of 4 sets of 10 repetitions of leg press and leg extension at 80 % 1RM. Supplements were ingested peri-exercise, and venous blood and muscle biopsies were obtained pre-exercise (PRE), and at 30, 120, and 360 min post-exercise. Serum IGF-1 was determined with ELISA, and skeletal muscle mRNA expression of myostatin, ACTRIIB, p21kip, p27kip, CDK2, cyclin B1, cyclin D1, Myo-D, myogenin, MRF-4, and myf5 was determined using real-time PCR. Results were analyzed by two-way ANOVA for serum IGF-1 and two-way MANOVA for mRNA expression. Serum IGF-1 in CHO + BCAA was greater than PLC ( p < 0.05) but was not affected by RE ( p > 0.05). A significant group × time interaction was located for cylin D1 ( p < 0.05), but not for any other genes. However, significant time effects were noted for cyclin B1 and p21cip ( p < 0.05). At 30, 120 and 360 min post-exercise, p21cip was significantly less than PRE. Cyclin D1 was greater than PRE and 30 min post-exercise at 120 and 360 min post-exercise, whereas cyclin B1 was significantly greater than PRE at 120 min post-exercise ( p < 0.05). Unlike the co-ingestion of CHO with either BCAA or l -leucine in conjunction with RE, the expression of various myogenically related genes were up-regulated with RE.