Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Bispebjerg Hospital and Center for Healthy Aging, University of Copenhagen, Copenhagen NV, Denmark.
Am J Physiol Endocrinol Metab. 2011 Jan;300(1):E231-42. doi: 10.1152/ajpendo.00513.2010. Epub 2010 Nov 2.
Muscle protein turnover following resistance exercise and amino acid availability are relatively well described. By contrast, the beneficial effects of different sources of intact proteins in relation to exercise need further investigation. Our objective was to compare muscle anabolic responses to a single bolus intake of whey or casein after performance of heavy resistance exercise. Young male individuals were randomly assigned to participate in two protein trials (n = 9) or one control trial (n = 8). Infusion of l-[1-(13)C]leucine was carried out, and either whey, casein (0.3 g/kg lean body mass), or a noncaloric control drink was ingested immediately after exercise. l-[1-(13)C]leucine-labeled whey and casein were used while muscle protein synthesis (MPS) was assessed. Blood and muscle tissue samples were collected to measure systemic hormone and amino acid concentrations, tracer enrichments, and myofibrillar protein synthesis. Western blots were used to investigate the Akt signaling pathway. Plasma insulin and branched-chain amino acid concentrations increased to a greater extent after ingestion of whey compared with casein. Myofibrillar protein synthesis was equally increased 1-6 h postexercise after whey and casein intake, both of which were higher compared with control (P < 0.05). Phosphorylation of Akt and p70(S6K) was increased after exercise and protein intake (P < 0.05), but no differences were observed between the types of protein except for total 4E-BP1, which was higher after whey intake than after casein intake (P < 0.05). In conclusion, whey and casein intake immediately after resistance exercise results in an overall equal MPS response despite temporal differences in insulin and amino acid concentrations and 4E-BP1.
肌肉蛋白质在抗阻运动后的周转率和氨基酸的可获得性已得到了较为详细的描述。相比之下，不同完整蛋白质来源在与运动相关时的有益效果还需要进一步研究。我们的目的是比较在进行大强度抗阻运动后，单次摄入乳清蛋白或酪蛋白对肌肉合成代谢的影响。年轻男性个体被随机分配到两个蛋白试验（n = 9）或一个对照试验（n = 8）中。进行 L-[1-(13)C]亮氨酸输注，并在运动后立即摄入乳清蛋白、酪蛋白（0.3 g/kg 去脂体重）或非热量对照饮料。使用 L-[1-(13)C]亮氨酸标记乳清蛋白和酪蛋白来评估肌肉蛋白合成（MPS）。采集血液和肌肉组织样本以测量系统激素和氨基酸浓度、示踪剂丰度以及肌原纤维蛋白合成。使用 Western blot 技术来研究 Akt 信号通路。与摄入酪蛋白相比，摄入乳清蛋白后可使血浆胰岛素和支链氨基酸浓度更大程度地增加。在摄入乳清蛋白和酪蛋白后 1-6 h 时，肌原纤维蛋白合成同样增加，与对照组相比均更高（P < 0.05）。在运动和蛋白质摄入后，Akt 和 p70(S6K)的磷酸化均增加（P < 0.05），但除了总 4E-BP1 外，两种蛋白质之间没有差异，摄入乳清蛋白后总 4E-BP1 更高（P < 0.05）。总之，尽管胰岛素和氨基酸浓度以及 4E-BP1 存在时间差异，但在进行抗阻运动后立即摄入乳清蛋白和酪蛋白会导致整体相等的 MPS 反应。
