Supplementation of a suboptimal protein dose with leucine or essential amino acids: effects on myofibrillar protein synthesis at rest and following resistance exercise in men

Citations Over TimeTop 1% of 2012 papers

Abstract

Leucine is a nutrient regulator of muscle protein synthesis by activating mTOR and possibly other proteins in this pathway. The purpose of this study was to examine the role of leucine in the regulation of human myofibrillar protein synthesis (MPS). Twenty-four males completed an acute bout of unilateral resistance exercise prior to consuming either: a dose (25 g) of whey protein (WHEY); 6.25 g whey protein with total leucine equivalent to WHEY (LEU); or 6.25 g whey protein with total essential amino acids (EAAs) equivalent to WHEY for all EAAs except leucine (EAA-LEU). Measures of MPS, signalling through mTOR, and amino acid transporter (AAT) mRNA abundance were made while fasted (FAST), and following feeding under rested (FED) and post-exercise (EX-FED) conditions. Leucinaemia was equivalent between WHEY and LEU and elevated compared to EAA-LEU (P=0.001). MPS was increased above FAST at 1–3 h post-exercise in both FED (P <0.001) and EX-FED (P <0.001) conditions with no treatment effect.At 3–5 h, only WHEY remained significantly elevated above FAST in EX-FED(WHEY 184% vs. LEU 55% and EAA-LEU 35%; P =0.036). AAT mRNA abundance was increased above FAST after feeding and exercise with no effect of leucinaemia. In summary, a low dose of whey protein supplemented with leucine or all other essential amino acids was as effective as a complete protein (WHEY) in stimulating postprandial MPS; however only WHEY was able to sustain increased rates of MPS post-exercise and may therefore be most suited to increase exercise-induced muscle protein accretion.

Related Papers

• → Acute Hormonal Responses to Submaximal and Maximal Heavy Resistance and Explosive Exercises in Men and Women(2005)163 cited
• → Myofibrillar Protein Catabolism is Rapidly Suppressed Following Protein Feeding(1998)48 cited
• → The Effects of Resistance Training Using Elastic Band on Anabolic Hormones and Functional Fitness in Aged Women(2018)1 cited
• → Faculty Opinions recommendation of Muscle protein anabolic resistance to essential amino acids does not occur in healthy older adults before or after resistance exercise training.(2018)
• → The effect of four weeks of resistance training with and without blood flow restriction on levels of anabolic and catabolic hormonal markers in middle-age sedentary males(2022)