Witard Oliver C, Tieland Michael, Beelen Milou, Tipton Kevin D, van Loon Luc J C, Koopman René
School of Sport and Exercise Sciences, University of Birmingham, Birmingham, UNITED KINGDOM.
Med Sci Sports Exerc. 2009 Jan;41(1):144-54. doi: 10.1249/MSS.0b013e3181844e79.
We examined the impact of an acute bout of resistance-type exercise on mixed muscle protein synthesis in the fed state.
After a standardized breakfast, 10 untrained males completed a single, unilateral lower-limb resistance-type exercise session. A primed, continuous infusion of l-[ring-C6]phenylalanine was combined with muscle biopsy collection from both the exercised (Ex) and the nonexercised (NEx) leg to assess the impact of local muscle contractions on muscle protein synthesis rates after food intake. Western blotting with phosphospecific and pan antibodies was used to determine the phosphorylation status of AMP-activated kinase (AMPK), 4E-binding protein (4E-BP1), mammalian target of rapamycin (mTOR), and p70 ribosomal protein S6 kinase (S6K1).
Muscle protein synthesis rates were approximately 20% higher in Ex compared with NEx (0.098% +/- 0.005% vs 0.083% +/- 0.002%.h, respectively, P < 0.01). In the fed state, resistance-type exercise did not elevate AMPK phosphorylation. However, the phosphorylation status of 4E-BP1 was approximately 20% lower after cessation of exercise in Ex compared with NEx (P < 0.05). Conversely, 4E-BP1 phosphorylation was significantly higher in Ex compared with NEx after 6 h of recovery (P < 0.05) with no changes in mTOR phosphorylation. S6 phosphorylation was greater in Ex versus NEx after cessation of exercise (P < 0.05), although S6K1 phosphorylation at T was not up-regulated (P > 0.05).
We conclude that resistance-type exercise performed in a fed state further elevates postprandial muscle protein synthesis rates, which is accompanied by an increase in S6 and 4E-BP1 phosphorylation state.
我们研究了一次急性抗阻型运动对进食状态下混合肌肉蛋白质合成的影响。
在标准化早餐后，10名未经训练的男性完成了一次单侧下肢抗阻型运动训练。将一次静脉推注后持续输注l-[环-C6]苯丙氨酸与对运动侧（Ex）和非运动侧（NEx）腿部进行肌肉活检相结合，以评估局部肌肉收缩对进食后肌肉蛋白质合成速率的影响。使用磷酸特异性抗体和泛抗体进行蛋白质免疫印迹，以确定AMP激活的蛋白激酶（AMPK）、4E结合蛋白（4E-BP1）、雷帕霉素靶蛋白（mTOR）和p70核糖体蛋白S6激酶（S6K1）的磷酸化状态。
与NEx相比，Ex的肌肉蛋白质合成速率大约高20%（分别为0.098%±0.005%和0.083%±0.002%·h，P<0.01）。在进食状态下，抗阻型运动并未提高AMPK的磷酸化水平。然而，与NEx相比，运动停止后Ex的4E-BP1磷酸化状态降低了约20%（P<0.05）。相反，恢复6小时后，Ex的4E-BP1磷酸化水平显著高于NEx（P<0.05），而mTOR的磷酸化水平没有变化。运动停止后，Ex的S6磷酸化水平高于NEx（P<0.05），尽管S6K1在苏氨酸位点的磷酸化水平未上调（P>0.05）。
我们得出结论，在进食状态下进行的抗阻型运动会进一步提高餐后肌肉蛋白质合成速率，同时伴随着S6和4E-BP1磷酸化状态的增加。
