Blood flow restriction exercise stimulates mTORC1 signaling and muscle protein synthesis in older men

• Published in: Journal of applied physiology (1985) Vol. 108; no. 5; pp. 1199 - 1209
• Main Authors: Fry, Christopher S., Glynn, Erin L., Drummond, Micah J., Timmerman, Kyle L., Fujita, Satoshi, Abe, Takashi, Dhanani, Shaheen, Volpi, Elena, Rasmussen, Blake B.
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Physiological Society 01.05.2010
• Subjects: Age Factors; Aged; Biological and medical sciences; Biomarkers - blood; Biopsy; Blood pressure; Blotting, Western; Exercise; Fibrin Fibrinogen Degradation Products - metabolism; Fundamental and applied biological sciences. Psychology; Hormones - blood; Humans; Insulin - metabolism; Male; Mechanistic Target of Rapamycin Complex 1; Men; Mitogen-Activated Protein Kinases - metabolism; Multiprotein Complexes; Muscle Contraction; Muscle Proteins - biosynthesis; Muscle Proteins - genetics; Older people; Organ Size; Oxygen - blood; Phosphorylation; Protein synthesis; Proteins; Quadriceps Muscle - anatomy & histology; Quadriceps Muscle - blood supply; Quadriceps Muscle - metabolism; Recovery of Function; Regional Blood Flow; Resistance Training; Ribosomal Protein S6 - metabolism; Ribosomal Protein S6 Kinases, 70-kDa - metabolism; Sex Factors; Signal Transduction; Thrombosis - blood; Time Factors; TOR Serine-Threonine Kinases; Transcription Factors - metabolism; Physical exercise; Human; Occlusion; Senescence; Ageing; Striated muscle; S6 kinase 1; Blood flow; Signal transduction; Vertebrata; Mammalia; Protein synthesis; Hemodynamics; aging; resistance exercise; skeletal muscle; sarcopenia
• ISSN: 8750-7587; 1522-1601; 1522-1601
• DOI: 10.1152/japplphysiol.01266.2009

The loss of skeletal muscle mass during aging, sarcopenia, increases the risk for falls and dependence. Resistance exercise (RE) is an effective rehabilitation technique that can improve muscle mass and strength; however, older individuals are resistant to the stimulation of muscle protein synthesis (MPS) with traditional high-intensity RE. Recently, a novel rehabilitation exercise method, low-intensity RE, combined with blood flow restriction (BFR), has been shown to stimulate mammalian target of rapamycin complex 1 (mTORC1) signaling and MPS in young men. We hypothesized that low-intensity RE with BFR would be able to activate mTORC1 signaling and stimulate MPS in older men. We measured MPS and mTORC1-associated signaling proteins in seven older men (age 70 ± 2 yr) before and after exercise. Subjects were studied identically on two occasions: during BFR exercise [bilateral leg extension exercise at 20% of 1-repetition maximum (1-RM) with pressure cuff placed proximally on both thighs and inflated at 200 mmHg] and during exercise without the pressure cuff (Ctrl). MPS and phosphorylation of signaling proteins were determined on successive muscle biopsies by stable isotopic techniques and immunoblotting, respectively. MPS increased 56% from baseline after BFR exercise ( P < 0.05), while no change was observed in the Ctrl group ( P > 0.05). Downstream of mTORC1, ribosomal S6 kinase 1 (S6K1) phosphorylation and ribosomal protein S6 (rpS6) phosphorylation increased only in the BFR group after exercise ( P < 0.05). We conclude that low-intensity RE in combination with BFR enhances mTORC1 signaling and MPS in older men. BFR exercise is a novel intervention that may enhance muscle rehabilitation to counteract sarcopenia.