Spiering Barry A, Kraemer William J, Anderson Jeffrey M, Armstrong Lawrence E, Nindl Bradley C, Volek Jeff S, Judelson Daniel A, Joseph Michael, Vingren Jakob L, Hatfield Disa L, Fragala Maren S, Ho Jen-Yu, Maresh Carl M
Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT 06269, USA.
Med Sci Sports Exerc. 2008 Jun;40(6):1039-48. doi: 10.1249/MSS.0b013e31816722bd.
Hormones and muscle contraction alter protein kinase B (Akt) signaling via distinct mechanisms. Therefore, the purpose of this study was to determine whether physiologically elevated circulating hormones modulate resistance exercise (RE)-induced signaling of Akt and its downstream targets. We hypothesized that elevated circulating hormones would potentiate the signaling response.
Seven healthy men (mean +/- SD age, 27 +/- 4 yr; body mass, 79.1 +/- 13.6 kg; body fat, 16% +/- 7%) performed two identical lower-body RE protocols (five sets of five maximal repetitions of knee extensions) in a randomized order and separated by 1-3 wk: one protocol was preceded by rest [low-circulating hormonal concentration (LHC) trial], and the other was preceded by a bout of high-volume upper-body RE using short rest periods designed to elicit a large increase in circulating hormones [high-circulating hormonal concentration (HHC) trial].
The HHC trial invoked significantly (P < or = 0.05) greater growth hormone (GH) and cortisol concentrations compared with the LHC trial. There were minimal differences between trials in insulin and insulin-like growth factor-I (IGF-I) concentrations. Contrary to our hypothesis, 70-kDa ribosomal protein S6 kinase (p70 S6K) threonine (Thr) 389 phosphorylation within the vastus lateralis was attenuated at 180 min post-RE during the HHC trial. RE did not affect Akt or glycogen synthase kinase-3beta (GSK-3beta) phosphorylation nor were there differences between trials. Immediately post-RE, eukaryotic initiation factor (eIF) 4E binding protein-1 (4E-BP1) phosphorylation declined, and adenosine monophosphate-activated protein kinase (AMPK) phosphorylation increased; however, there were no differences between trials in these variables.
p70 S6K Thr 389 phosphorylation was attenuated during the HHC trial despite dramatically greater (>2.5-fold) circulating GH concentrations; this was potentially due to cortisol-induced inhibition of p70 S6K Thr 389 phosphorylation.
激素和肌肉收缩通过不同机制改变蛋白激酶B（Akt）信号传导。因此，本研究旨在确定生理水平升高的循环激素是否会调节抗阻运动（RE）诱导的Akt及其下游靶点的信号传导。我们假设循环激素水平升高会增强信号反应。
七名健康男性（平均±标准差年龄，27±4岁；体重，79.1±13.6千克；体脂，16%±7%）以随机顺序进行两种相同的下肢抗阻运动方案（五组，每组五次最大重复次数的膝关节伸展），间隔1-3周：一种方案前先休息[低循环激素浓度（LHC）试验]，另一种方案前先进行一轮高容量上肢抗阻运动，使用短休息时间以引起循环激素大幅增加[高循环激素浓度（HHC）试验]。
与LHC试验相比，HHC试验引起的生长激素（GH）和皮质醇浓度显著更高（P≤0.05）。胰岛素和胰岛素样生长因子-I（IGF-I）浓度在试验之间差异最小。与我们的假设相反，在HHC试验中，RE后180分钟时，股外侧肌内70 kDa核糖体蛋白S6激酶（p70 S6K）苏氨酸（Thr）389磷酸化减弱。RE未影响Akt或糖原合酶激酶-3β（GSK-3β）磷酸化，试验之间也无差异。RE后即刻，真核起始因子（eIF）4E结合蛋白-1（4E-BP1）磷酸化下降，腺苷单磷酸激活蛋白激酶（AMPK）磷酸化增加；然而，这些变量在试验之间无差异。
尽管循环GH浓度显著更高（>2.5倍），但在HHC试验中p70 S6K Thr 389磷酸化仍减弱；这可能是由于皮质醇诱导的对p70 S6K Thr 389磷酸化的抑制。
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