Health and Exercise Science Research Group, University of Stirling, Stirling, United Kingdom (OCW and KDT); Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom (SRJ); the School of Sport and Exercise Sciences, University of Birmingham, Birmingham, United Kingdom (LB); and Metabolic Physiology, Medical Research Council and Arthritis Research United Kingdom Centre for Excellence in Musculoskeletal Ageing, School of Graduate Entry Medicine and Health, University of Nottingham, Derby, United Kingdom (KS and AS).
Am J Clin Nutr. 2014 Jan;99(1):86-95. doi: 10.3945/ajcn.112.055517. Epub 2013 Nov 20.
The intake of whey, compared with casein and soy protein intakes, stimulates a greater acute response of muscle protein synthesis (MPS) to protein ingestion in rested and exercised muscle.
We characterized the dose-response relation of postabsorptive rates of myofibrillar MPS to increasing amounts of whey protein at rest and after exercise in resistance-trained, young men.
Volunteers (n = 48) consumed a standardized, high-protein (0.54 g/kg body mass) breakfast. Three hours later, a bout of unilateral exercise (8 × 10 leg presses and leg extensions; 80% one-repetition maximum) was performed. Volunteers ingested 0, 10, 20, or 40 g whey protein isolate immediately (~10 min) after exercise. Postabsorptive rates of myofibrillar MPS and whole-body rates of phenylalanine oxidation and urea production were measured over a 4-h postdrink period by continuous tracer infusion of labeled [(13)C6] phenylalanine and [(15)N2] urea.
Myofibrillar MPS (mean ± SD) increased (P < 0.05) above 0 g whey protein (0.041 ± 0.015%/h) by 49% and 56% with the ingestion of 20 and 40 g whey protein, respectively, whereas no additional stimulation was observed with 10 g whey protein (P > 0.05). Rates of phenylalanine oxidation and urea production increased with the ingestion of 40 g whey protein.
A 20-g dose of whey protein is sufficient for the maximal stimulation of postabsorptive rates of myofibrillar MPS in rested and exercised muscle of ~80-kg resistance-trained, young men. A dose of whey protein >20 g stimulates amino acid oxidation and ureagenesis. This trial was registered at http://www.isrctn.org/ as ISRCTN92528122.
与摄入酪蛋白和大豆蛋白相比，乳清蛋白可更大程度地刺激休息和运动肌肉中的肌肉蛋白合成（MPS）对蛋白质摄入的急性反应。
我们在经过力量训练的年轻男性中，确定了在休息和运动后，乳清蛋白的吸收后率与肌原纤维 MPS 的剂量反应关系。
志愿者（n=48）摄入了标准化的高蛋白（0.54 g/kg 体重）早餐。三小时后，进行了一次单侧运动（8 次 10 腿推和腿伸展；80%一次重复最大）。志愿者在运动后立即（约 10 分钟）摄入 0、10、20 或 40 g 乳清蛋白分离物。在 4 小时的饮后期间，通过连续输注标记的[（13）C6]苯丙氨酸和[（15）N2]尿素来测量肌原纤维 MPS 的吸收后率和全身苯丙氨酸氧化和尿素生成率。
肌原纤维 MPS（平均值±标准差）高于 0 g 乳清蛋白（0.041±0.015%/h），分别增加了 49%和 56%，摄入 20 和 40 g 乳清蛋白时，而摄入 10 g 乳清蛋白时则没有观察到额外的刺激（P＞0.05）。摄入 40 g 乳清蛋白后，苯丙氨酸氧化和尿素生成率增加。
对于 80-kg 左右经过力量训练的年轻男性，20 g 乳清蛋白剂量足以最大程度地刺激休息和运动肌肉中肌原纤维 MPS 的吸收后率。乳清蛋白剂量＞20 g 会刺激氨基酸氧化和尿素生成。该试验在 http://www.isrctn.org/ 注册为 ISRCTN92528122。
