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/p70S6K
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 p70S6K total protein were similar between groups, and did not change postintervention. Further, Akt and p70S6K 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.
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hypertrophie du muscle squelettique;
skeletal muscle hypertrophy;
Document Type: Research Article
School of Medicine – University of São Paulo, São Paulo, SP, Brazil.
School of Physical Education and Sport, University of Sao Paulo, SP, Brazil.
Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil.
Federal University of São Paulo. São Paulo, SP, Brazil.
April 13, 2011
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