40 gr whey: doble insulina, misma síntesis

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40 gr whey: doble insulina, misma síntesis

Notapor Fisio » Sab, 01 Mar 2014, 00:19

Tipton is back, sobre todo pone de forma algo más tangible a lo que se ha hecho el papel de la insulinemia a nivel fisiológico, no sale en el resumen, pero 20 gr vs 40 gr de whey se traduce en doble insulinemia pero básicamente la misma FSR

Myofibrillar muscle protein synthesis rates subsequent to a meal in response to increasing doses of whey protein at rest and after resistance exercise.
Witard OC1, Jackman SR, Breen L, Smith K, Selby A, Tipton KD.
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Abstract
BACKGROUND:

The intake of whey, compared with casein and soy protein intakes, stimulates a greater acute response of muscle protein synthesis (MPS) to protein ingestion in rested and exercised muscle.
OBJECTIVE:

We characterized the dose-response relation of postabsorptive rates of myofibrillar MPS to increasing amounts of whey protein at rest and after exercise in resistance-trained, young men.
DESIGN:

Volunteers (n = 48) consumed a standardized, high-protein (0.54 g/kg body mass) breakfast. Three hours later, a bout of unilateral exercise (8 × 10 leg presses and leg extensions; 80% one-repetition maximum) was performed. Volunteers ingested 0, 10, 20, or 40 g whey protein isolate immediately (~10 min) after exercise. Postabsorptive rates of myofibrillar MPS and whole-body rates of phenylalanine oxidation and urea production were measured over a 4-h postdrink period by continuous tracer infusion of labeled [(13)C6] phenylalanine and [(15)N2] urea.
RESULTS:

Myofibrillar MPS (mean ± SD) increased (P < 0.05) above 0 g whey protein (0.041 ± 0.015%/h) by 49% and 56% with the ingestion of 20 and 40 g whey protein, respectively, whereas no additional stimulation was observed with 10 g whey protein (P > 0.05). Rates of phenylalanine oxidation and urea production increased with the ingestion of 40 g whey protein.
CONCLUSIONS:

A 20-g dose of whey protein is sufficient for the maximal stimulation of postabsorptive rates of myofibrillar MPS in rested and exercised muscle of ~80-kg resistance-trained, young men. A dose of whey protein >20 g stimulates amino acid oxidation and ureagenesis. This trial was registered at http://www.isrctn.org/ as ISRCTN92528122.


http://www.ncbi.nlm.nih.gov/pubmed/24257722

Asumimos que la insulina no tiene un papel en la hipertrofia? O en la FSR? ;)
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Re: 40 gr whey: doble insulina, misma síntesis

Notapor Fisio » Dom, 02 Mar 2014, 00:22

Fijaos que interesante, un año antes el mismo grupo de Stuart publicó un estudio que encontró que sin embargo mejor 40 gr que 20 gr en personas mayores, de nuevo basadonos en FSR.


Resistance exercise enhances myofibrillar protein synthesis with graded intakes of whey protein in older men
Yifan Yanga1, Leigh Breena1, Nicholas A. Burda1, Amy J. Hectora1, Tyler A. Churchward-Vennea1, Andrea R. Jossea1, M. A. Tarnopolskya2 and Stuart M. Phillipsa1 c1

a1 Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, 1280 Main Street West, Hamilton, ON, Canada L8S 4K1

a2 Pediatrics and Neurology, McMaster University, Hamilton, ON, Canada

Abstract

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.
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