Document Detail


Enhanced Amino Acid Sensitivity of Myofibrillar Protein Synthesis Persists for up to 24 h after Resistance Exercise in Young Men.
MedLine Citation:
PMID:  21289204     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
We aimed to determine whether an exercise-mediated enhancement of muscle protein synthesis to feeding persisted 24 h after resistance exercise. We also determined the impact of different exercise intensities (90% or 30% maximal strength) or contraction volume (work-matched or to failure) on the response at 24 h of recovery. Fifteen men (21 ± 1 y, BMI = 24.1 ± 0.8 kg•m(-2)) received a primed, constant infusion of l-[ring-(13)C(6)]phenylalanine to measure muscle protein synthesis after protein feeding at rest (FED; 15 g whey protein) and 24 h after resistance exercise (EX-FED). Participants performed unilateral leg exercises: 1) 4 sets at 90% of maximal strength to failure (90FAIL); 2) 30% work-matched to 90FAIL (30WM); or 3) 30% to failure (30FAIL). Regardless of condition, rates of mixed muscle protein and sarcoplasmic protein synthesis were similarly stimulated at FED and EX-FED. In contrast, protein ingestion stimulated rates of myofibrillar protein synthesis above fasting rates by 0.016 ± 0.002%/h and the response was enhanced 24 h after resistance exercise, but only in the 90FAIL and 30FAIL conditions, by 0.038 ± 0.012 and 0.041 ± 0.010, respectively. Phosphorylation of protein kinase B on Ser473 was greater than FED at EX-FED only in 90FAIL, whereas phosphorylation of mammalian target of rapamycin on Ser2448 was significantly increased at EX-FED above FED only in the 30FAIL condition. Our results suggest that resistance exercise performed until failure confers a sensitizing effect on human skeletal muscle for at least 24 h that is specific to the myofibrillar protein fraction.
Authors:
Nicholas A Burd; Daniel W D West; Daniel R Moore; Philip J Atherton; Aaron W Staples; Todd Prior; Jason E Tang; Michael J Rennie; Steven K Baker; Stuart M Phillips
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-2-2
Journal Detail:
Title:  The Journal of nutrition     Volume:  -     ISSN:  1541-6100     ISO Abbreviation:  -     Publication Date:  2011 Feb 
Date Detail:
Created Date:  2011-2-3     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0404243     Medline TA:  J Nutr     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Exercise Metabolism Research Group, Department of Kinesiology, Hamilton, Ontario L8S 4K1, Canada.
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