Muscle-building effect of protein beverages for athletes investigated

Tuesday 20 August 2013

Islamabad, Aug 21 (Newswire): Physical activity requires strong, healthy muscles. Fortunately, when people exercise on a regular basis, their muscles experience a continuous cycle of muscle breakdown (during exercise) and compensatory remodeling and growth (especially with weightlifting).

Athletes have long experimented with methods to augment these physiologic responses to enhance muscle growth. One such ergogenic aid that has gained recent popularity is the use of high-quality, high-protein beverages during and after exercise, with dairy-based drinks enriched with whey proteins often taking front stage.

Many studies have documented a beneficial effect of their consumption. Of particular interest is the effect of the essential amino acid leucine contained in these products. Two papers, published in The American Journal of Clinical Nutrition, report the results of two independent studies conducted to understand better how amino acids influence protein synthesis in recreational athletes.

According to ASN Spokesperson Shelley McGuire, PhD: "These studies, and others like them, help us understand and apply something we all inherently know: the human body works in a complex, yet completely logical way! It makes good sense that consuming a food containing high-quality protein (like milk) during and/or immediately following exercise would help muscles get stronger. Muscle strength doesn't just happen on its own -- our muscles need to be both encouraged (as happens via exercise) and nourished (as happens when we eat well). Now we have even more scientific proof for this common-sense concept."

In the first study, researchers led by Stuart Phillips (McMaster University) investigated whether postexercise muscle protein synthesis is different when a large, single dose of whey protein (25 g) is consumed immediately after activity compared with when smaller doses (2.5 g) are consumed 10 times over an extended period. The idea with the small "protein shots" was to mimic how another milk protein, casein, is digested. Participants (8 men; mean age: 22 y) performed 8 sets of 8-10 repetitions on a leg-extension machine; each subject participated in both dietary treatment regimens.

In the second study led by Stefan Pasiakos from the US Army Research Institute of Environmental Medicine, active-duty military personnel (7 men and 1 woman; mean age: 24 y) consumed a high-protein beverage (10 g protein as essential amino acids) containing 1.87 or 3.5 g leucine while exercising on a stationary bicycle. In both studies, postexercise muscle protein synthesis was evaluated.

Consuming the large bolus of whey protein immediately after exercise increased muscle protein synthesis more than when periodic smaller doses of protein were consumed. In the second study, muscle protein synthesis was 33% greater after consumption of the leucine-enriched protein beverage than after the lower-leucine drink.

The researchers concluded that muscle metabolism after exercise can be manipulated via dietary means. In terms of the most beneficial timing of protein intake, immediate postexercise consumption appears to be best. Furthermore, leucine may play an especially important role in stimulating muscle growth in the postactivity recovery period.

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Majority of pharmaceutical ads do not adhere to FDA guidelines

Islamabad, Aug 21 (Newswire): A study led by Mount Sinai School of Medicine researchers of 192 pharmaceutical advertisements in biomedical journals found that only 18 percent were compliant with Food and Drug Administration (FDA) guidelines, and over half failed to quantify serious risks including death.

"Marketing research has consistently shown that journal advertising is the most profitable form of drug marketing, with an estimated return on investment of five dollars for every dollar spent," said Dr. Deborah Korenstein, lead author of the study and Associate Professor of Medicine at Mount Sinai School of Medicine. "Our study, the first in nearly 20 years to provide a systematic assessment of the adherence of US advertisements to FDA guidance, shows that the current system is not in the best interest of the health of the public."

Researchers performed a cross-sectional analysis of prescription pharmaceutical advertisements published in nine journals. They evaluated adherence to FDA standards and the presence of content that is important for physicians to use when safely prescribing the drugs. Of the 192 advertisements for 82 unique products, only 15 fully adhered to all 20 FDA Prescription Drug Advertising Guidelines. In addition, 57.8 percent of the advertisements did not quantify serious risks, 48.2 percent lacked verifiable references, and 28.9 percent failed to present adequate efficacy quantification.

"The limited resources of the FDA's Division of Drug Marketing and Advertising are a major barrier to successful regulation of the pharmaceutical industry's multi-billion dollar marketing budget," said Dr. Korenstein.

"We are hopeful that an update in FDA regulations, with increased emphasis on the transparent presentation of basic safety and efficacy information, might improve the quality of information provided in physician-directed pharmaceutical advertisements."

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Switch in cell's 'power plant' declines with age, rejuvenated by drug

Islamabad, Aug 21 (Newswire): Researchers at the Johns Hopkins University School of Medicine have found a protein normally involved in blood pressure regulation in a surprising place: tucked within the little "power plants" of cells, the mitochondria.

The quantity of this protein appears to decrease with age, but treating older mice with the blood pressure medication losartan can increase protein numbers to youthful levels, decreasing both blood pressure and cellular energy usage.

The researchers say these findings, published in the Proceedings of the National Academy of Sciences, may lead to new treatments for mitochondrial-specific, age-related diseases, such as diabetes, hearing loss, frailty and Parkinson's disease.

"We've identified a functional and independently operated system that appears to influence energy regulation within the mitochondria," explains Jeremy Walston, M.D., professor of geriatric medicine at Hopkins. "This mitochondrial angiotensin system is activated by commonly utilized blood pressure medications, and influences both nitric oxide and energy production when signaled."

Previous research showed that manipulating angiotensin in the body's cells had unexpectedly affected mitochondrial energy production, so Walston and Peter Abadir , M.D., an assistant professor of geriatric medicine, decided to examine the role of angiotensin within the mitochondria. Using high-powered microscopy, they and their collaborators found evidence within the mitochondria of angiotensin as well as one of the protein receptors that bind to and detect it. They also pinpointed the angiotensin receptor's exact locations within the mitochondria of mouse kidney, liver, neuron and heart cells as well as in human white blood cells.

The team then treated mitochondria with a chemical known to activate the angiotensin receptors and measured the cell's response. This resulted in a decrease in oxygen consumption by half and a small increase in nitric oxide production -- indicating less energy made by the mitochondria and lowered blood pressure, respectively. Explains Walston, "Activating angiotensin receptors within the mitochondria with these agents led to lowered blood pressure and decreased cellular energy use."

But they found even more than just an energy-regulating mechanism; after testing the angiotensin system in mitochondria of both young and old mice, they noticed a decrease by almost a third of the amount of the angiotensin receptor type 2 in the mitochondria in older mice, meaning that cells in older mice were unable to control energy use as well. The researchers then tried treating these older mice with the blood pressure lowering drug losartan daily for 20 weeks and found that the number of these receptors increased.

"Treatment of the old mice with losartan resulted in a marked increase in the number of receptors that are known to positively influence blood pressure and decrease inflammation," says Walston.

Declining mitochondria are known to influence chronic diseases in older adults, explains Walston, whose next step is to translate studies from cell culture and animal based studies to human studies in hopes of developing new therapies. "Our findings will help us determine if the drugs that interact with this receptor will also lead to improvement of mitochondrial function and energy production. This, in turn, could facilitate the treatment of a number of chronic diseases of older adults.

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