Effect of eccentric exercise velocity on akt/mtor/p70^s6ksignaling in human skeletal muscle

Abstract

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.

Bone Marrow Mesenchymal Stem Cells (BM-MSCs) Improve Heart Function in Swine Myocardial Infarction Model through Paracrine Effects

“…have shown that MSCs-derived exosomes could increase ATP levels, decrease oxidative stress and activate PI3K/Akt pathway to enhance myocardial viability and prevent adverse remodeling via increasing glycolysis after myocardial ischemia/reperfusion injury 15 . Moreover, previous studies on mTOR signal transduction pathway have revealed positive effects on skeletal muscle regeneration 16 17 18 19 . Considering mTOR signal pathway controls protein synthesis in different levels by increasing the translation of certain mRNAs, we hypothesize here that the activation of mTOR signal transduction pathway by paracrine action of BM-MSCs after myocardial infarction, will further increase cardiomyocyte protein synthesis and glucose metabolism, and then improve systolic function of heart.…”

The acute effects of strength, endurance and concurrent exercises on the Akt/mTOR/p70S6K1 and AMPK signaling pathway responses in rat skeletal muscle

“…However, Tamaki's exercise mode does not optimize the eccentric phase of the lifts. In humans, maximal eccentric contractions are reported to be effective in stimulating mTOR and p70 S6K1 via an Akt-independent pathway 18,19. This effect may be mediated by a combination of greater tension and stretching of the skeletal muscles during the descending phase of the lift.…”

Signaling Pathways that Mediate Skeletal Muscle Hypertrophy: Effects of Exercise Training

“…The subjects performed five sets of 8 repetitions of a slow or fast eccentric protocol and biopsies were collected at the following time intervals: baseline, immediately after, and two hours after the session. MGF expression was increased approximately 2.5 fold in slow eccentric contraction, and Akt and p70 s6K protein phosphorylation were higher in the fast eccentric protocol than at baseline, or slow or fast eccentric contraction, which suggests that the velocity has no direct influence on the activation of this pathway, and other signaling pathways could be selectively activated and involved in the response to high velocity eccentric contraction [62].…”