The muscle protein synthetic response to the combined ingestion of protein and carbohydrate is not impaired in healthy older men

Kiskini, Alexandra; Hamer, Henrike M.; Wall, Benjamin T.; Groen, Bart B. L.; Lange, Anneke de; Bakker, J.; Senden, Joan M.; Verdijk, Lex B.; Loon, Luc J. C. van

doi:10.1007/s11357-013-9522-2

Cited by 14 publications

(26 citation statements)

References 40 publications

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“…; Kiskini et al. ). This heterogeneity in study findings may be due to a number of lifestyle factors such as long‐term diet and physical activity patterns which may promote dissociation between chronological age and anabolic sensitivity (Churchward‐Venne et al.…”

Section: Discussionmentioning

confidence: 97%

Dose-dependent increases in p70S6K phosphorylation and intramuscular branched-chain amino acids in older men following resistance exercise and protein intake

et al. 2014

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Resistance exercise and whey protein supplementation are effective strategies to activate muscle cell anabolic signaling and ultimately promote increases in muscle mass and strength. In the current study, 46 healthy older men aged 60–75 (69.0 ± 0.55 years, 85.9 ± 1.8 kg, 176.8 ± 1.0 cm) performed a single bout of unaccustomed lower body resistance exercise immediately followed by ingestion of a noncaloric placebo beverage or supplement containing 10, 20, 30, or 40 g of whey protein concentrate (WPC). Intramuscular amino acid levels in muscle biopsy samples were measured by Gas Chromatography–Mass Spectrometry (GC‐MS) at baseline (before exercise and WPC supplementation) plus at 2 h and 4 h post exercise. Additionally, the extent of p70S6K phosphorylation at Thr389 in muscle biopsy homogenates was assessed by western blot. Resistance exercise alone reduced intramuscular branch chain amino acid (BCAA; leucine, isoleucine, and valine) content. Supplementation with increasing doses of whey protein prevented this fall in muscle BCAAs during postexercise recovery and larger doses (30 g and 40 g) significantly augmented postexercise muscle BCAA content above that observed following placebo ingestion. Additionally, the fold change in the phosphorylation of p70S6K (Thr389) at 2 h post exercise was correlated with the dose of whey protein consumed (r = 0.51, P < 001) and was found to be significantly correlated with intramuscular leucine content (r = 0.32, P = 0.026). Intramuscular BCAAs, and leucine in particular, appear to be important regulators of anabolic signaling in aged human muscle during postexercise recovery via reversal of exercise‐induced declines in intramuscular BCAAs.

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Section: Discussionmentioning

confidence: 97%

Dose-dependent increases in p70S6K phosphorylation and intramuscular branched-chain amino acids in older men following resistance exercise and protein intake

et al. 2014

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“…Aging necessarily leads to disuse/inactivity via illness, hospitalization, and adoption of a more sedentary routine. Consequently, anabolic resistance may be an expected , but perhaps not requisite , feature of biological aging.…”

Section: Regulation Of Skeletal Mps By Exercise/physical Activity In mentioning

confidence: 99%

“…Churchward-Venne, Breen and Phillips hospitalization, and adoption of a more sedentary routine. Consequently, anabolic resistance may be an expected [9,28,29], but perhaps not requisite [33,[52][53][54], feature of biological aging.…”

Section: Figmentioning

confidence: 99%

Alterations in human muscle protein metabolism with aging: Protein and exercise as countermeasures to offset sarcopenia

2013

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Aging is associated with a reduction in skeletal muscle mass-sarcopenia-the etiology of which is multifactorial. One mechanism is that aging has, as one of its hallmarks, a reduced sensitivity of skeletal muscle to the normally potent anabolic effects of protein feeding and resistance exercise, and to the anticatabolic effects of insulin, the combination of which has been termed "anabolic resistance." However, this reduced sensitivity of skeletal muscle to anabolic stimuli may, in some cases, be overcome by providing a greater quantity of the nutrition and/or exercise stimulus. Daily habitual physical activity appears to be a primary determinant of anabolic resistance as we have recently shown that as little as 14 days of reduced ambulatory activity was sufficient to induce anabolic resistance in the elderly by attenuating the postprandial increase in muscle protein synthesis (MPS). The etiology of anabolic resistance is complex and may include alterations in amino acid uptake/utilization, cell signaling status, muscle blood flow, and microvascular perfusion (impacting amino acid delivery and availability). Further, there appears to be sexual dimorphism with advancing age in the response of MPS to amino acid/insulin provision. Maintenance of physical activity during aging is of fundamental importance for skeletal muscle to allow it to appropriately respond to the anabolic effects of nutrition.

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“…Recently, we have reported on the use of highly labeled milk proteins, without the administration of intravenous tracer infusions, to assess the change in the mixed muscle-bound L-[1-13 C]phenylalanine enrichments (⌬MPE) over the postprandial phase (14,15,35). Here, we matched our previous efforts in the production of milk proteins labeled with large amounts of L-[1-13 C]phenylalanine (ϳ39 MPE) (26,34) and show it is possible to measure changes in the L-[1-13 C]phenylalanine enrichments in the myofibrillar-bound fraction (Table 1).…”

Section: Discussionmentioning

confidence: 99%

“…The muscle protein-bound L-[1-13 C]phenylalanine enrichment derived from the orally ingested tracer gives an indication of the metabolic fate of dietary proteinderived amino acids toward de novo muscle protein deposition. As such, the dietary protein-derived amino acid tracer incorporation allows for direct insight into the anabolic potential of a protein containing meal (12,15,24,35).…”

Section: Discussionmentioning

confidence: 99%

The use of doubly labeled milk protein to measure postprandial muscle protein synthesis rates in vivo in humans

Burd

Cermak

Kouw

et al. 2014

Journal of Applied Physiology

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We aimed to determine the impact of precursor pool dilution on the assessment of postprandial myofibrillar protein synthesis rates (MPS). A Holstein dairy cow was infused with large amounts of L-[1-(13)C]phenylalanine and L-[1-(13)C]leucine, and the milk was collected and fractionated. The enrichment levels in the casein were 38.7 and 9.3 mole percent excess, respectively. In a subsequent human experiment, 11 older men (age: 71 ± 1 y, body mass index: 26 ± 0.1 kg·m(-2)) received a primed constant infusion of L-[ring-(2)H5]phenylalanine and L-[1-(13)C]leucine. Blood and muscle samples were collected before and after the ingestion of 20-g doubly labeled casein to assess postprandial MPS based on the 1) constant tracer infusion of L-[ring-(2)H5]phenylalanine, 2) ingestion of intrinsically L-[1-(13)C]phenylalanine-labeled casein, and 3) constant infusion of L-[1-(13)C]leucine in combination with the ingestion of intrinsically L-[1-(13)C]leucine-labeled casein. Postprandial MPS was increased (P < 0.05) after protein ingestion (∼70% above postabsorptive values) based on the L-[1-(13)C]leucine tracer. There was no significant stimulation of postprandial MPS (∼27% above postabsorptive values) when the calculated fractional synthesis rate was based on the L-[ring-(2)H5]phenylalanine (P = 0.2). Comparisons of postprandial MPS based on the primed continuous infusion of L-[1-(13)C]leucine or the ingestion of intrinsically L-[1-(13)C]phenylalanine-labeled casein protein demonstrated differences compared with the primed continuous infusion of L-[ring-(2)H5]phenylalanine (P > 0.05). Our findings confirm that the postprandial MPS assessed using the primed continuous tracer infusion approach may differ if tracer steady-state conditions in the precursor pools are perturbed. The use of intrinsically doubly labeled protein provides a method to study the metabolic fate of the ingested protein and the subsequent postprandial MPS response.

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The muscle protein synthetic response to the combined ingestion of protein and carbohydrate is not impaired in healthy older men

Cited by 14 publications

References 40 publications

Dose-dependent increases in p70S6K phosphorylation and intramuscular branched-chain amino acids in older men following resistance exercise and protein intake

Dose-dependent increases in p70S6K phosphorylation and intramuscular branched-chain amino acids in older men following resistance exercise and protein intake

Alterations in human muscle protein metabolism with aging: Protein and exercise as countermeasures to offset sarcopenia

The use of doubly labeled milk protein to measure postprandial muscle protein synthesis rates in vivo in humans

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