Resistance exercise enhances myofibrillar protein synthesis with graded intakes of whey protein in older men.
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.
Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, 1280 Main Street West, Hamilton, ON, Canada              L8S 4K1.
Yifan
Y
Yang
Leigh
L
Breen
Nicholas A
NA
Burd
Amy J
AJ
Hector
Tyler A
TA
Churchward-Venne
Andrea R
AR
Josse
M A
MA
Tarnopolsky
Stuart M
SM
Phillips
D000368:Aged; D000596:Amino Acids; D002247:Carbon Isotopes; D004032:Diet; D019587:Dietary Supplements; D015444:Exercise / Q000502:physiology*; D005504:Food Analysis; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D008894:Milk Proteins / Q000494:pharmacology*; D009210:Myofibrils / Q000235:genetics / Q000378:metabolism*; D000067816:Whey Proteins
D000596:Amino Acids; D002247:Carbon Isotopes; D007328:Insulin; D008894:Milk Proteins; D000067816:Whey Proteins