HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Free Full Text (PDF) Free A corrigendum has been published All Versions of this Article: 103/3/903    most recent 00195.2007v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (7) Citing Articles via Google Scholar Google Scholar Articles by Fujita, S. Articles by Rasmussen, B. B. Search for Related Content PubMed PubMed Citation Articles by Fujita, S. Articles by Rasmussen, B. B.

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

Departments of ¹Internal Medicine and ²Physical Therapy; and ³Division of Rehabilitation Sciences, University of Texas Medical Branch, Galveston, Texas; and ⁴Department of Human and Engineered Environmental Studies, Graduate School of Frontier Sciences, University of Tokyo, Chiba, Japan

Submitted 16 February 2007 ; accepted in final form 11 June 2007

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.

mammalian target of rapamycin; ischemia; hypertrophy; protein metabolism; postexercise recovery

This article has been cited by other articles:

				N. A. Burd, J. E. Tang, D. R. Moore, and S. M. Phillips Exercise training and protein metabolism: influences of contraction, protein intake, and sex-based differences J Appl Physiol, May 1, 2009; 106(5): 1692 - 1701. [Abstract] [Full Text] [PDF]

				N. K. McGhee, L. S. Jefferson, and S. R. Kimball Elevated Corticosterone Associated with Food Deprivation Upregulates Expression in Rat Skeletal Muscle of the mTORC1 Repressor, REDD1 J. Nutr., May 1, 2009; 139(5): 828 - 834. [Abstract] [Full Text] [PDF]

				S. Al-Majid and D. P. Gray A Biobehavioral Model for the Study of Exercise Interventions in Cancer-related Fatigue Biol Res Nurs, April 1, 2009; 10(4): 381 - 391. [Abstract] [PDF]

				T. Suga, K. Okita, N. Morita, T. Yokota, K. Hirabayashi, M. Horiuchi, S. Takada, T. Takahashi, M. Omokawa, S. Kinugawa, et al. Intramuscular metabolism during low-intensity resistance exercise with blood flow restriction J Appl Physiol, April 1, 2009; 106(4): 1119 - 1124. [Abstract] [Full Text] [PDF]

				D. R. Moore and N. A. Burd Exercise intensity matters for both young and old muscles J. Physiol., February 1, 2009; 587(3): 511 - 512. [Full Text] [PDF]

				S. B. Wilkinson, S. M. Phillips, P. J. Atherton, R. Patel, K. E. Yarasheski, M. A. Tarnopolsky, and M. J. Rennie Differential effects of resistance and endurance exercise in the fed state on signalling molecule phosphorylation and protein synthesis in human muscle J. Physiol., August 1, 2008; 586(15): 3701 - 3717. [Abstract] [Full Text] [PDF]

				S. Al-Majid and H. Waters The biological mechanisms of cancer-related skeletal muscle wasting: the role of progressive resistance exercise. Biol Res Nurs, July 1, 2008; 10(1): 7 - 20. [Abstract] [PDF]