NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, Netherlands.
NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, Netherlands
Am J Clin Nutr. 2015 Oct;102(4):828-36. doi: 10.3945/ajcn.114.103184. Epub 2015 Sep 9.
Protein consumed after resistance exercise increases postexercise muscle protein synthesis rates. To date, dairy protein has been studied extensively, with little known about the capacity of other protein-dense foods to augment postexercise muscle protein synthesis rates.
We aimed to compare protein digestion and absorption kinetics, postprandial amino acid availability, anabolic signaling, and the subsequent myofibrillar protein synthetic response after the ingestion of milk compared with beef during recovery from resistance-type exercise.
In crossover trials, 12 healthy young men performed a single bout of resistance exercise. Immediately after cessation of exercise, participants ingested 30 g protein by consuming isonitrogenous amounts of intrinsically l-[1-(13)C]phenylalanine-labeled beef or milk. Blood and muscle biopsy samples were collected at rest and after exercise during primed continuous infusions of l-[ring-(2)H5]phenylalanine and l-[ring-3,5-(2)H2]tyrosine to assess protein digestion and absorption kinetics, plasma amino acid availability, anabolic signaling, and subsequent myofibrillar protein synthesis rates in vivo in young men.
Beef protein-derived phenylalanine appeared more rapidly in circulation compared with milk ingestion (P < 0.001). The availability of phenylalanine during the 5-h postexercise period tended to be higher after beef (64% ± 3%) ingestion than after milk ingestion (57% ± 3%; P = 0.08). Both beef and milk ingestion were followed by an increase in the phosphorylation of mammalian target of rapamycin complex 1 and 70-kDa S6 protein kinase 1 during postexercise recovery. Milk ingestion increased myofibrillar protein synthesis rates to a greater extent than did beef ingestion during the 0- to 2-h postexercise phase (P = 0.013). However, the increase in myofibrillar protein synthesis rates did not differ between milk and beef ingestion during the entire 0- to 5-h postexercise phase (P = 0.114).
Both milk and beef ingestion augment the postexercise myofibrillar protein synthetic response in young men, with a stronger stimulation of myofibrillar protein synthesis during the early postprandial stage after milk ingestion. This trial was registered at www.clinicaltrials.gov as NCT01578590.
抗阻运动后摄入蛋白质会增加运动后肌肉蛋白质合成速率。迄今为止，人们已经对乳蛋白进行了广泛的研究，但对于其他高蛋白食物增强运动后肌肉蛋白质合成速率的能力知之甚少。
我们旨在比较牛奶和牛肉在抗阻运动恢复期间摄入后，蛋白质消化吸收动力学、餐后氨基酸可用性、合成代谢信号和随后的肌原纤维蛋白合成反应，以评估它们对运动后肌肉蛋白质合成的影响。
在交叉试验中，12 名健康年轻男性进行了一次抗阻运动。运动停止后立即，参与者通过摄入等氮量的天然标记有 l-[1-(13)C]苯丙氨酸的牛肉或牛奶来摄入 30g 蛋白质。在静息和运动期间，通过连续脉冲输注 l-[环-(2)H5]苯丙氨酸和 l-[环-3,5-(2)H2]酪氨酸，采集血液和肌肉活检样本，以评估年轻男性体内蛋白质消化吸收动力学、血浆氨基酸可用性、合成代谢信号和随后的肌原纤维蛋白合成率。
与牛奶摄入相比，牛肉蛋白衍生的苯丙氨酸更快地出现在循环中（P < 0.001）。在运动后 5 小时内，牛肉（64% ± 3%）摄入后的苯丙氨酸可用性倾向于高于牛奶（57% ± 3%；P = 0.08）。牛肉和牛奶摄入后，哺乳动物雷帕霉素靶蛋白复合物 1 和 70kDa S6 蛋白激酶 1 的磷酸化均增加。在运动后恢复期间，牛奶摄入比牛肉摄入更能增加肌原纤维蛋白合成率（0 至 2 小时，P = 0.013）。然而，在整个 0 至 5 小时的运动后阶段，牛奶和牛肉摄入之间的肌原纤维蛋白合成率增加没有差异（P = 0.114）。
牛奶和牛肉摄入均能增加年轻男性运动后的肌原纤维蛋白合成反应，牛奶摄入后早期的餐后阶段更能刺激肌原纤维蛋白的合成。本试验在 www.clinicaltrials.gov 上注册为 NCT01578590。
