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BFR Exercise Increases S6K1 Phosphorylation in Type‐I and Type‐II Skeletal Muscle Fibers
Author(s) -
Gundermann David M,
Walker Dillon K,
Fry Christopher S,
Dickinson Jared M,
Drummond Micah J,
Volpi Elena,
Rasmussen Blake B
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.1064.6
Subject(s) - p70 s6 kinase 1 , mtorc1 , ribosomal protein s6 , phosphorylation , medicine , endocrinology , skeletal muscle , chemistry , biology , biochemistry , protein kinase b
Restriction of blood flow to a contracting muscle during low‐intensity resistance exercise (BFR exercise) stimulates mTORC1 signaling and muscle protein synthesis during post‐exercise recovery. However, it is unknown if mTORC1 activation is occurring in all muscle fiber types. The aim of our study was to determine whether ribosomal S6 kinase 1 (S6K1), a downstream effector of mTORC1, is activated in primarily fast twitch muscle fibers. Young men performed 4 sets of leg extensions at a 20% 1‐RM while a pressure cuff was inflated restricting blood flow to the quadriceps, then released immediately following exercise. Muscle biopsies were collected from the vastus lateralis at baseline, 1 and 3 hr post‐exercise. Western blotting confirmed an increase in mTOR, S6K1, and S6 phosphorylation in whole muscle homogenates post‐exercise. Epifluorescence microscopy was used to assess mTORC1 activation in individual fiber types of muscle samples. We show that phospho‐S6K1 is localized to the perinuclear space prior to exercise and following exercise there is a progressive increase in S6K1 phosphorylation and translocation to the sarcoplasm in type‐I and type‐II muscle fibers. Our preliminary results suggest that BFR exercise increases mTORC1 activation in both slow and fast‐twitch muscle fiber types. Supported by NIH/NIAMS RO1 AR049877 , P30AG024832, NIH 1UL1RR029876‐01 and T32HD07539.