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Randomized Controlled Trial
, 34 (3), 191-8

Periexercise Coingestion of Branched-Chain Amino Acids and Carbohydrate in Men Does Not Preferentially Augment Resistance Exercise-Induced Increases in Phosphatidylinositol 3 Kinase/Protein Kinase B-mammalian Target of Rapamycin Pathway Markers Indicative of Muscle Protein Synthesis

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Randomized Controlled Trial

Periexercise Coingestion of Branched-Chain Amino Acids and Carbohydrate in Men Does Not Preferentially Augment Resistance Exercise-Induced Increases in Phosphatidylinositol 3 Kinase/Protein Kinase B-mammalian Target of Rapamycin Pathway Markers Indicative of Muscle Protein Synthesis

Maria Pontes Ferreira et al. Nutr Res.

Abstract

The effects of a single bout of resistance exercise (RE) in conjunction with periexercise branched-chain amino acid (BCAA) and carbohydrate (CHO) ingestion on skeletal muscle signaling markers indicative of muscle protein synthesis were determined. It was hypothesized that CHO + BCAA would elicit a more profound effect on these signaling markers compared with CHO. Twenty-seven males were randomly assigned to CHO, CHO + BCAA, or placebo (PLC) groups. Four sets of leg presses and leg extensions were performed at 80% 1 repetition maximum. Supplements were ingested 30 minutes and immediately before and after RE. Venous blood and muscle biopsy samples were obtained immediately before supplement ingestion and 0.5, 2, and 6 hours after RE. Serum insulin and glucose and phosphorylated levels of muscle insulin receptor substrate 1 (IRS-1), protein kinase B, mammalian target of rapamycin, phosphorylated 70S6 kinase, and 4E binding protein 1 were assessed. Data were analyzed by 2-way repeated-measures analysis of variance. Significant group × time interactions were observed for glucose and insulin (P < .05) showing that CHO and CHO + BCAA were significantly greater than PLC. Significant time main effects were observed for IRS-1 (P = .001), protein kinase B (P = .031), mammalian target of rapamycin (P = .003), and phosphorylated 70S6 kinase (P = .001). Carbohydrate and CHO + BCAA supplementation significantly increased IRS-1 compared with PLC (P = .002). However, periexercise coingestion of CHO and BCAA did not augment RE-induced increases in skeletal muscle signaling markers indicative of muscle protein synthesis when compared with CHO.

Keywords: Branched-chain amino acids; Carbohydrate; Insulin; Men; Muscle protein synthesis.

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