Document Detail


Resistance exercise enhances myofibrillar protein synthesis with graded intakes of whey protein in older men.
MedLine Citation:
PMID:  22313809     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Feeding stimulates robust increases in muscle protein synthesis (MPS); however, ageing may alter the anabolic response to protein ingestion and the subsequent aminoacidaemia. With this as background, we aimed to determine in the present study the dose-response of MPS with the ingestion of isolated whey protein, with and without prior resistance exercise, in the elderly. For the purpose of this study, thirty-seven elderly men (age 71 (sd 4) years) completed a bout of unilateral leg-based resistance exercise before ingesting 0, 10, 20 or 40 g of whey protein isolate (W0-W40, respectively). Infusion of l-[1-13C]leucine and l-[ring-13C6]phenylalanine with bilateral vastus lateralis muscle biopsies were used to ascertain whole-body leucine oxidation and 4 h post-protein consumption of MPS in the fed-state of non-exercised and exercised leg muscles. It was determined that whole-body leucine oxidation increased in a stepwise, dose-dependent manner. MPS increased above basal, fasting values by approximately 65 and 90 % for W20 and W40, respectively (P < 0·05), but not with lower doses of whey. While resistance exercise was generally effective at stimulating MPS, W20 and W40 ingestion post-exercise increased MPS above W0 and W10 exercised values (P < 0·05) and W40 was greater than W20 (P < 0·05). Based on the study, the following conclusions were drawn. At rest, the optimal whey protein dose for non-frail older adults to consume, to increase myofibrillar MPS above fasting rates, was 20 g. Resistance exercise increases MPS in the elderly at all protein doses, but to a greater extent with 40 g of whey ingestion. These data suggest that, in contrast to younger adults, in whom post-exercise rates of MPS are saturated with 20 g of protein, exercised muscles of older adults respond to higher protein doses.
Authors:
Yifan Yang; Leigh Breen; Nicholas A Burd; Amy J Hector; Tyler A Churchward-Venne; Andrea R Josse; M A Tarnopolsky; Stuart M Phillips
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-2-7
Journal Detail:
Title:  The British journal of nutrition     Volume:  -     ISSN:  1475-2662     ISO Abbreviation:  -     Publication Date:  2012 Feb 
Date Detail:
Created Date:  2012-2-8     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0372547     Medline TA:  Br J Nutr     Country:  -    
Other Details:
Languages:  ENG     Pagination:  1-9     Citation Subset:  -    
Affiliation:
Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, 1280 Main Street West, Hamilton, ON, Canada L8S 4K1.
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