Department of Physical Performance, Norwegian School of Sport Sciences, P.O. Box 4014 Ullevål Stadion, 0806 Oslo, Norway.
Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, P.O. Box 1046, Blindern, 0317 Oslo, Norway.
J Int Soc Sports Nutr. 2017 Nov 21;14:43. doi: 10.1186/s12970-017-0202-y. eCollection 2017.
Protein intake is essential to maximally stimulate muscle protein synthesis, and the amino acid leucine seems to possess a superior effect on muscle protein synthesis compared to other amino acids. Native whey has higher leucine content and thus a potentially greater anabolic effect on muscle than regular whey (WPC-80). This study compared the acute anabolic effects of ingesting 2 × 20 g of native whey protein, WPC-80 or milk protein after a resistance exercise session.
24 young resistance trained men and women took part in this double blind, randomized, partial crossover, controlled study. Participants received either WPC-80 and native whey ( = 10), in a crossover design, or milk ( = 12). Supplements were ingested immediately (20 g) and two hours after (20 g) a bout of heavy-load lower body resistance exercise. Blood samples and muscle biopsies were collected to measure plasma concentrations of amino acids by gas-chromatography mass spectrometry, muscle phosphorylation of p70S6K, 4E-BP1 and eEF-2 by immunoblotting, and mixed muscle protein synthesis by use of [H]phenylalanine-infusion, gas-chromatography mass spectrometry and isotope-ratio mass spectrometry. Being the main comparison, differences between native whey and WPC-80 were analysed by a one-way ANOVA and comparisons between the whey supplements and milk were analysed by a two-way ANOVA.
Native whey increased blood leucine concentrations more than WPC-80 and milk ( < 0.05). Native whey ingestion induced a greater phosphorylation of p70S6K than milk 180 min after exercise ( = 0.03). Muscle protein synthesis rates increased 1-3 h hours after exercise with WPC-80 (0.119%), and 1-5 h after exercise with native whey (0.112%). Muscle protein synthesis rates were higher 1-5 h after exercise with native whey than with milk (0.112% vs. 0.064, = 0.023).
Despite higher-magnitude increases in blood leucine concentrations with native whey, it was not superior to WPC-80 concerning effect on muscle protein synthesis and phosphorylation of p70S6K during a 5-h post-exercise period. Native whey increased phosphorylation of p70S6K and muscle protein synthesis rates to a greater extent than milk during the 5-h post exercise period.
This study was retrospectively registered at clinicaltrials.gov as NCT02968888.
蛋白质摄入对于最大限度地刺激肌肉蛋白质合成至关重要，而亮氨酸似乎比其他氨基酸对肌肉蛋白质合成具有更优越的作用。天然乳清蛋白的亮氨酸含量更高，因此比普通乳清蛋白（WPC-80）对肌肉具有更大的合成代谢作用。本研究比较了在抗阻运动后摄入 2×20 克天然乳清蛋白、WPC-80 或牛奶蛋白对肌肉的急性合成代谢影响。
24 名年轻的抗阻训练男性和女性参加了这项双盲、随机、部分交叉、对照研究。参与者采用交叉设计，分别接受 WPC-80 和天然乳清蛋白（n=10）或牛奶（n=12）。补充剂在一次大负荷下肢抗阻运动后立即（20 克）和两小时后（20 克）摄入。通过气相色谱-质谱法测定血液样本和肌肉活检中氨基酸的血浆浓度，通过免疫印迹法测定 p70S6K、4E-BP1 和 eEF-2 的肌肉磷酸化水平，通过使用[H]苯丙氨酸输注、气相色谱-质谱法和同位素比质谱法测定混合肌肉蛋白合成。作为主要比较，通过单向方差分析分析天然乳清蛋白与 WPC-80 之间的差异，通过双向方差分析分析乳清补充剂与牛奶之间的差异。
与 WPC-80 和牛奶相比，天然乳清蛋白使血液亮氨酸浓度升高（p<0.05）。与运动后 180 分钟的牛奶相比，运动后 180 分钟时，天然乳清蛋白使 p70S6K 磷酸化水平更高（p=0.03）。WPC-80 可使运动后 1-3 小时的肌肉蛋白合成率升高（0.119%），运动后 1-5 小时的肌肉蛋白合成率升高（0.112%）。与牛奶相比，运动后 1-5 小时时，天然乳清蛋白的肌肉蛋白合成率更高（0.112% vs. 0.064%，p=0.023）。
尽管天然乳清蛋白使血液亮氨酸浓度升高幅度更大，但在 5 小时的运动后恢复期内，其对肌肉蛋白合成和 p70S6K 磷酸化的作用并不优于 WPC-80。与牛奶相比，天然乳清蛋白在运动后 5 小时内更能增加 p70S6K 磷酸化和肌肉蛋白合成率。
本研究在 clinicaltrials.gov 上作为 NCT02968888 进行了回顾性注册。
