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
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
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DOI：
10.1113/jphysiol.2012.228833
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发表时间：
2012-06-01
影响因子：
5.5
通讯作者：
Phillips, Stuart M.
中科院分区：
文献类型：
--
作者：
Churchward-Venne, Tyler A.;Burd, Nicholas A.;Phillips, Stuart M.
关键点必需氨基酸（EAA）刺激肌原纤维蛋白合成（MPS）的速率增加。亮氨酸是啮齿类动物MPS的关键调节因子;然而，其相对于其他EAA的重要性尚不清楚。大约20克的蛋白质最大限度地刺激年轻男性抵抗运动后的MPS，但我们不知道是否可以通过添加某些氨基酸使更小的剂量更好。我们报告说，一个次优剂量的乳清蛋白（6.25克）补充亮氨酸或EAA的混合物没有亮氨酸刺激MPS类似于25克乳清蛋白在休息条件下，然而，只有25克乳清维持运动诱导率的MPS。在次优剂量的乳清中添加亮氨酸或不含亮氨酸的EAA混合物与25 g乳清在刺激MPS的进食率方面一样有效;然而，25 g乳清更适合于增加运动诱导的肌肉阻力。摘要亮氨酸是肌肉蛋白质合成的营养调节剂，通过激活mTOR和可能的其他蛋白质在这一途径。本研究的目的是研究亮氨酸在人肌原纤维蛋白合成（MPS）的调节中的作用。24名男性在食用以下任一种之前完成了急性回合的单侧阻力运动：一剂（25 g）乳清蛋白（WHEY）; 6.25 g乳清蛋白，其总亮氨酸相当于WHEY（LEU）;或6.25 g乳清蛋白，其总必需氨基酸（EAA）相当于除亮氨酸外的所有必需氨基酸（EAA-LEU）。在禁食（FAST）、休息喂养（FED）和运动后（EX-FED）条件下测量MPS、mTOR信号传导和氨基酸转运蛋白（AAT）mRNA丰度。与EAA-LEU相比，WHEY和LEU之间的白细胞血症相当，并且升高（P =0.001）。在FED（P < 0.001）和EX-FED（P < 0.001）条件下，运动后13 h MPS均高于FAST，但无治疗效应。在35 h时，在EX-FED中仅WHEY保持显著升高高于FAST（WHEY 184% vs. LEU 55%和EAA-LEU 35%; P= 0.036）。AAT mRNA丰度增加FAST以上喂养和运动后，没有影响白血病。总之，补充亮氨酸或所有其他必需氨基酸的低剂量乳清蛋白在刺激餐后MPS方面与完全蛋白（WHEY）一样有效;然而，只有WHEY能够维持运动后MPS的增加速率，因此可能最适合增加运动诱导的肌肉蛋白质增加。
Key points Essential amino acids (EAAs) stimulate increased rates of myofibrillar protein synthesis (MPS). Leucine is a key regulator of MPS in rodents; however, its importance relative to the other EAAs is not clear. About 20 g of protein maximally stimulates MPS after resistance exercise in young men, but we do not know if smaller doses can be made better by adding certain amino acids. We report that a suboptimal dose of whey protein (6.25 g) supplemented with either leucine or a mixture of EAAs without leucine stimulates MPS similar to 25 g of whey protein under resting conditions; however, only 25 g of whey sustains exercise-induced rates of MPS. Adding leucine or a mixture of EAAs without leucine to a suboptimal dose of whey is as effective as 25 g whey at stimulating fed rates of MPS; however, 25 g of whey is better suited to increase resistance exercise-induced muscle anabolism. 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 13 h post-exercise in both FED (P < 0.001) and EX-FED (P < 0.001) conditions with no treatment effect. At 35 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.