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Influence of supplementation with branched-chain amino acids in combination with resistance exercise on p70S6 kinase phosphorylation in resting and exercising human skeletal muscle.
MedLine Citation:
PMID:  20528801     Owner:  NLM     Status:  In-Process    
Abstract/OtherAbstract:
AIM: Skeletal muscle growth is thought to be regulated by the mammalian target of rapamycin (mTOR) pathway, which can be activated by resistance exercise and branched-chain amino acids (BCAA). The major aim of the present study was to distinguish between the influence of resistance exercise and BCAA on key enzymes considered to be involved in the regulation of protein synthesis, including p70(S6) kinase (p70(S6k)).
METHODS: Nine healthy subjects (four men and five women) performed unilateral resistance exercise on two occasions separated by 1 month. Subjects were randomly supplied either a mixture of BCAA or flavoured water. Muscle biopsies were taken from both resting and exercising muscle before, after and 1 h after exercise.
RESULTS: Phosphorylation of Akt was unaltered by either resistance exercise and/or BCAA supplementation whereas mTOR phosphorylation was enhanced (P<0.05) to a similar extent in both exercising and resting muscle following exercise in the absence (70-90%) and presence of BCAA supplementation (80-130%). Phosphorylation of p70(S6k) was unaffected by resistance exercise alone; however, BCAA intake increased (P<0.05) this phosphorylation in both legs following exercise. In resting muscle, a 5- and 16-fold increase in p70(S6k) was observed immediately after and 1 h after exercise, respectively, as compared to 11- and 30-fold increases in the exercising muscle. Phosphorylation of eukaryotic elongation factor 2 was attenuated 1 h after exercise (P<0.05) in both resting (10-40%) and exercising muscle (30-50%) under both conditions.
CONCLUSION: The present findings indicate that resistance exercise and BCAA exert both separate and combined effects on the p70(S6k) phosphorylation in an Akt-independent manner.
Authors:
W Apró; E Blomstrand
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Acta physiologica (Oxford, England)     Volume:  200     ISSN:  1748-1716     ISO Abbreviation:  Acta Physiol (Oxf)     Publication Date:  2010 Nov 
Date Detail:
Created Date:  2010-11-02     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101262545     Medline TA:  Acta Physiol (Oxf)     Country:  England    
Other Details:
Languages:  eng     Pagination:  237-48     Citation Subset:  IM    
Copyright Information:
© 2010 The Authors. Journal compilation © 2010 Scandinavian Physiological Society.
Affiliation:
Åstrand Laboratory, Swedish School of Sport and Health Sciences, Stockholm, Sweden.
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