Resistance exercise enhances myofibrillar protein synthesis with graded intakes of whey protein in older men

TY - JOUR

T1 - Resistance exercise enhances myofibrillar protein synthesis with graded intakes of whey protein in older men

AU - Yang, Yifan

AU - Breen, Leigh

AU - Burd, Nicholas A

AU - Hector, Amy J

AU - Churchward-Venne, Tyler A

AU - Josse, Andrea R

AU - Tarnopolsky, M A

AU - Phillips, Stuart M

PY - 2012/11/28

Y1 - 2012/11/28

N2 - 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.

AB - 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.

KW - Amino Acids

KW - Food Analysis

KW - Humans

KW - Aged

KW - Exercise

KW - Insulin

KW - Myofibrils

KW - Dietary Supplements

KW - Gene Expression Regulation

KW - Milk Proteins

KW - Diet

KW - Male

KW - Carbon Isotopes

U2 - 10.1017/S0007114511007422

DO - 10.1017/S0007114511007422

M3 - Article

C2 - 22313809

VL - 108

SP - 1780

EP - 1788

JO - The British journal of nutrition

JF - The British journal of nutrition

SN - 0007-1145

IS - 10

ER -