Blood flow restriction during low-intensity resistance exercise increases S6K1 phosphorylation and muscle protein synthesis

Satoshi Fujita, Takashi Abe, Micah J. Drummond, Jerson G. Cadenas, Hans C. Dreyer, Yoshiaki Sato, Elena Volpi, Blake Rasmussen

Research output: Contribution to journalArticle

229 Citations (Scopus)

Abstract

Low-intensity resistance exercise training combined with blood flow restriction (REFR) increases muscle size and strength as much as conventional resistance exercise with high loads. However, the cellular mechanism(s) underlying the hypertrophy and strength gains induced by REFR are unknown. We have recently shown that both the mammalian target of rapamycin (mTOR) signaling pathway and muscle protein synthesis (MPS) were stimulated after an acute bout of high-intensity resistance exercise in humans. Therefore, we hypothesized that an acute bout of REFR would enhance mTOR signaling and stimulate MPS. We measured MPS and phosphorylation status of mTOR-associated signaling proteins in six young male subjects. Subjects were studied once during blood flow restriction (REFR, bilateral leg extension exercise at 20% of 1 repetition maximum while a pressure cuff was placed on the proximal end of both thighs and inflated at 200 mmHg) and a second time using the same exercise protocol but without the pressure cuff [control (Ctrl)]. MPS in the vastus lateralis muscle was measured by using stable isotope techniques, and the phosphorylation status of signaling proteins was determined by immunoblotting. Blood lactate, cortisol, and growth hormone were higher following REFR compared with Ctrl (P < 0.05). Ribosomal S6 kinase 1 (S6K1) phosphorylation, a downstream target of mTOR, increased concurrently with a decreased eukaryotic translation elongation factor 2 (eEF2) phosphorylation and a 46% increase in MPS following REFR (P < 0.05). MPS and S6K1 phosphorylation were unchanged in the Ctrl group postexercise. We conclude that the activation of the mTOR signaling pathway appears to be an important cellular mechanism that may help explain the enhanced muscle protein synthesis during REFR.

Original languageEnglish (US)
Pages (from-to)903-910
Number of pages8
JournalJournal of Applied Physiology
Volume103
Issue number3
DOIs
StatePublished - Sep 2007

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Ribosomal Protein S6 Kinases
Muscle Proteins
Sirolimus
Phosphorylation
Peptide Elongation Factor 2
Pressure
Resistance Training
Quadriceps Muscle
Muscle Strength
Thigh
Immunoblotting
Isotopes
Protein Kinases
Hypertrophy
Growth Hormone
Hydrocortisone
Lactic Acid
Leg
Proteins
Exercise

Keywords

  • Hypertrophy
  • Ischemia
  • Mammalian target of rapamycin
  • Postexercise recovery
  • Protein metabolism

ASJC Scopus subject areas

  • Physiology
  • Endocrinology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Blood flow restriction during low-intensity resistance exercise increases S6K1 phosphorylation and muscle protein synthesis. / Fujita, Satoshi; Abe, Takashi; Drummond, Micah J.; Cadenas, Jerson G.; Dreyer, Hans C.; Sato, Yoshiaki; Volpi, Elena; Rasmussen, Blake.

In: Journal of Applied Physiology, Vol. 103, No. 3, 09.2007, p. 903-910.

Research output: Contribution to journalArticle

Fujita, Satoshi ; Abe, Takashi ; Drummond, Micah J. ; Cadenas, Jerson G. ; Dreyer, Hans C. ; Sato, Yoshiaki ; Volpi, Elena ; Rasmussen, Blake. / Blood flow restriction during low-intensity resistance exercise increases S6K1 phosphorylation and muscle protein synthesis. In: Journal of Applied Physiology. 2007 ; Vol. 103, No. 3. pp. 903-910.
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