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IronMagLabs - Bodybuilding Supplements

The optimum dose of whey that bodybuilders and other strength athletes can use after training is 20 g, sports scientists at the University of Stirling in Scotland will report soon in the American Journal of Clinical Nutrition. The subjects that the researchers used were in their early twenties, so still very young. The Brits’ findings may not apply to older strength athletes.

The optimum dose of whey that bodybuilders and other strength athletes can use after training is 20 g, sports scientists at the University of Stirling in Scotland have reported in the American Journal of Clinical Nutrition. The subjects that the researchers used were in their early twenties, so still young. The Brits’ findings may not apply to older strength athletes.

Even research on a neutral substance like whey is sponsored these days. The British study saw the light of day thanks to GlaxoSmithKline Nutritional Healthcare, which provided research team leader Kevin Tipton with a study grant. In addition, GlaxoSmithKline produced the whey preparations that were tested, in this case, the whey isolate Lucozade.

The research results are handy for GlaxoSmithKline. The researchers discovered that, at least in very young men, 20 g whey after a weight training session provides the optimal stimulus for muscle building. Whey is not cheap, so if 20 g of the stuff produces an optimal effect, it’ll be easier for the product designers at GlaxoSmithKline to make a post-workout supplement that works well and is reasonably priced and has an attractive profit margin.

“GlaxoSmithKline Nutritional Healthcare was involved in the design, analysis, and interpretation of data”, reads the small print in the article.

Which doesn’t mean to say that the study is no good. Tipton is a respected researcher who has a reputation to keep up.

The researchers first got their 48 subjects to train their legs, doing 8 sets of 10 reps on the leg press, with 80 percent of the weight with which the subjects could just manage 1 rep. Ten minutes later the subjects were given 0, 10, 20 or 40 g whey.

The figure below shows that the FSR [the rate at which muscle fibres were synthesised] did not increase by a statistically significant amount after taking 10 g whey, but that it did do so after taking 20 or 40 g whey. Although the FSR was higher in the athletes that were given 40 g whey, the difference in FSR between the 20 and the 40 g group was not statistically significant.

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The figure above shows that the oxidation of the amino acid phenylalanine increased dramatically when 40 g whey was ingested. The Brits deduce from this that the body starts to burn amino acids at doses of whey above 20 g.

They saw the same effect in the concentration of urea in the body. Urea is protein that has been broken down and that the body has no more use for, except for excreting it in the urine. The concentration of urea in the blood increased sharply in the subjects that were given 40 g whey.

“It remains unknown whether the optimal dose of protein for the maximal stimulation of muscle protein synthesis differs between the 120-kg athlete and 80-kg male exerciser compared with the 60-kg female exerciser”, the researchers write. “Future studies should be designed to fully elucidate how muscle mass or the amount of muscle mass exercised influences the response of MPS to different doses of protein.”

Myofibrillar muscle protein synthesis rates subsequent to a meal in response to increasing doses of whey protein at rest and after resistance exercise.

Witard OC, Jackman SR, Breen L, Smith K, Selby A, Tipton KD.

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.

PMID: 24257722 [PubMed - in process]

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

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