School of Physical Education and Sport, University of Sao Paulo, SP, Brazil.
Appl Physiol Nutr Metab. 2011 Apr;36(2):283-90. doi: 10.1139/h10-111.
It has been suggested that muscle tension plays a major role in the activation of intracellular pathways for skeletal muscle hypertrophy via an increase in mechano growth factor (MGF) and other downstream targets. Eccentric exercise (EE) imposes a greater amount of tension on the active muscle. In particular, high-speed EE seems to exert an additional effect on muscle tension and, thus, on muscle hypertrophy. However, little is known about the effect of EE velocity on hypertrophy signaling. This study investigated the effect of acute EE-velocity manipulation on the Akt/mTORCI/p70(S6K) hypertrophy pathway. Twenty subjects were assigned to either a slow (20°·s(-1); ES) or fast EE (210°·s(-1); EF) group. Biopsies were taken from vastus lateralis at baseline (B), immediately after (T1), and 2 h after (T2) the completion of 5 sets of 8 repetitions of eccentric knee extensions. Akt, mTOR, and p70(S6K) total protein were similar between groups, and did not change postintervention. Further, Akt and p70(S6K) protein phosphorylation were higher at T2 than at B for ES and EF. MGF messenger RNA was similar between groups, and only significantly higher at T2 than at B in ES. The acute manipulation of EE velocity does not seem to differently influence intracellular hypertrophy signaling through the Akt/mTORCI/p70S6K pathway.
有人认为，肌肉张力通过增加机械生长因子（MGF）和其他下游靶点，在骨骼肌肉肥大的细胞内途径激活中发挥主要作用。离心运动（EE）会对活跃的肌肉施加更大的张力。特别是高速 EE 似乎对肌肉张力产生额外的影响，从而对肌肉肥大产生影响。然而，关于 EE 速度对肥大信号的影响知之甚少。本研究探讨了急性 EE 速度操纵对 Akt/mTORCI/p70(S6K) 肥大途径的影响。20 名受试者被分配到缓慢（20°·s(-1)；ES）或快速 EE（210°·s(-1)；EF）组。在基线（B）、运动后即刻（T1）和 8 次重复 5 组离心膝关节伸展运动完成后 2 小时（T2），从股外侧肌采集活检。Akt、mTOR 和 p70(S6K) 总蛋白在组间相似，且干预后无变化。此外，ES 和 EF 中，Akt 和 p70(S6K) 蛋白磷酸化在 T2 时高于 B 时。MGF 信使 RNA 在组间相似，仅在 ES 中 T2 时高于 B 时显著升高。EE 速度的急性操纵似乎不会通过 Akt/mTORCI/p70S6K 途径对细胞内肥大信号产生不同的影响。
