This study determined 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 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 determined with two-way ANOVA for serum IGF-1 and two-way MANOVA for mRNA expression. Serum IGF-1 in CHO and CHO+BCAA was greater than PLC (p < 0.05) but was not affected by RE (p > 0.05). Significant differences were detected between groups for myostatin, ActIIB, MyoD, and myf5 mRNA expression showing CHO to be significantly different than CHO+BCAA, CHO+LEU, and PLC (p < 0.05). At 30, 120 and 360 min post-exercise, p21cip was significantly less than PRE, whereas cyclin D1 was greater than PRE at 120 and 360 min post-exercise (p < 0.05). The co-ingestion of CHO with either BCAA or L-leucine in conjunction with RE had no preferential effect on serum IGF-1 or pre-translational markers indicative of myogenesis.
Dietetics and Clinical Nutrition | Exercise Physiology | Human and Clinical Nutrition
Li, R., Ferreira, M. P., Cooke, M. B., La Bounty, P., Campbell, B., Greenwood, M., Willoughby, D. S., & Kreider, R. B. (2015). 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. Amino Acids 47(6), pp. 1203-1213. http://dx.doi.org/10.1007/s00726-015-1947-8.