tjing
2013-10-14, 13:43
Acute molecular responses in untrained and trained muscle subjected to aerobic and resistance exercise training versus resistance training alone.
Abstract
AIM:
This study assessed and compared acute muscle molecular responses before and after 5 wks training, employing either aerobic (AE) and resistance exercise (RE) or RE only.
METHODS:
Ten men performed one-legged RE, while the contralateral limb performed AE followed by RE 6 h later (AE+RE). Before (untrained) and after (trained) the intervention, acute bouts of RE were performed with or without preceding AE. Biopsies were obtained from m. vastus lateralis of each leg PRE and 3 h POST RE to determine mRNA-levels of VEGF, PGC-1α, MuRF-1, atrogin-1, myostatin, and phosphorylation of mTOR, p70S6K, rpS6 and eEF2.
RESULTS:
PGC-1α and VEGF expression increased (P<0.05) after acute RE in the untrained, but not the trained state. These markers showed greater response after AE+RE than RE in either condition. Myostatin was lower after AE+RE than RE, both before and after training. AE+RE showed higher MuRF-1 and atrogin-1 expression than RE in the untrained, not the trained state. Exercise increased (P<0.05) p70S6K phosphorylation both before and after training, yet this increase tended to be more prominent for AE+RE than RE before training. Phosphorylation of p70S6K was greater in trained muscle. Changes in these markers did not correlate with exercise-induced alterations in strength or muscle size.
CONCLUSION:
Concurrent exercise in untrained skeletal muscle prompts global molecular responses consistent with resulting whole-muscle adaptations. Yet, training blunts the more robust anabolic response shown after AE+RE compared with RE. This study challenges the concept that single molecular markers could predict training-induced changes in muscle size or strength.
Acta Physiol (Oxf). 2013 Oct 1.
http://www.ncbi.nlm.nih.gov/pubmed/24112827
Abstract
AIM:
This study assessed and compared acute muscle molecular responses before and after 5 wks training, employing either aerobic (AE) and resistance exercise (RE) or RE only.
METHODS:
Ten men performed one-legged RE, while the contralateral limb performed AE followed by RE 6 h later (AE+RE). Before (untrained) and after (trained) the intervention, acute bouts of RE were performed with or without preceding AE. Biopsies were obtained from m. vastus lateralis of each leg PRE and 3 h POST RE to determine mRNA-levels of VEGF, PGC-1α, MuRF-1, atrogin-1, myostatin, and phosphorylation of mTOR, p70S6K, rpS6 and eEF2.
RESULTS:
PGC-1α and VEGF expression increased (P<0.05) after acute RE in the untrained, but not the trained state. These markers showed greater response after AE+RE than RE in either condition. Myostatin was lower after AE+RE than RE, both before and after training. AE+RE showed higher MuRF-1 and atrogin-1 expression than RE in the untrained, not the trained state. Exercise increased (P<0.05) p70S6K phosphorylation both before and after training, yet this increase tended to be more prominent for AE+RE than RE before training. Phosphorylation of p70S6K was greater in trained muscle. Changes in these markers did not correlate with exercise-induced alterations in strength or muscle size.
CONCLUSION:
Concurrent exercise in untrained skeletal muscle prompts global molecular responses consistent with resulting whole-muscle adaptations. Yet, training blunts the more robust anabolic response shown after AE+RE compared with RE. This study challenges the concept that single molecular markers could predict training-induced changes in muscle size or strength.
Acta Physiol (Oxf). 2013 Oct 1.
http://www.ncbi.nlm.nih.gov/pubmed/24112827