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For years, elite athletes and their trainers have known that in order to increase muscle mass and strength, it's necessary to work muscles to complete exhaustion, since it's at the brink of muscle failure where the body's ongoing protein synthesis is put on hold because available adenosine triphosphate (ATP) -- which is critical for protein synthesis -- is fully depleted by the contractions of the exercise. When the exercise ceases at the point of exhaustion, the body over-reacts, signaling muscle cell nuclei to drastically increase protein synthesis. It is thought that this results in super-increase of muscle protein.
This energy deprivation mechanism works in tandem with the body's natural response to the muscular micro-damage that occurs on the brink of exhaustion. Today, it's widely understood that this purely mechanical stress stimulates further muscular growth through the enlistment of cells closely associated with muscle cells, known as 'satellite cells'. In a 1997 study it was found that satellite cells are recruited when they somehow detect that the close association between their cell membrane and the muscle cell membrane has been disrupted. It is believed that they then supply extra nuclei to the neighboring muscle cell, which means more nuclei to instruct the manufacture of muscle proteins.
Simply put, exercising your muscles to exhaustion helps them to build up, both from the body's response to mechanical micro-trauma, as well as from the increased synthesis of protein. If it were possible to continue to work longer and harder at the point of virtual exhaustion, this benefit can be extended and enhanced – and emerging research is finding ways to do just that.
What we experience as fatigue and muscle failure is a reaction known as metabolic acidosis. This is the breakdown of ATP, which generates hydrogen ions. Muscle pH levels decline in response to these ions, and overall acidity in the muscle increases. This increasingly acidic environment inhibits the enzymes required to create more ATP, thus restricting the ability of our muscles to continue producing force.
Today, researchers are finding that it's possible to block the increase of hydrogen ions, thus stabilizing pH levels and prolonging muscular activity. This is done by 'buffers' or compounds in muscles that bond to the hydrogen ions, eliminating their tendency to multiply acidity. As it turns out, for skeletal muscle, clinical trials are revealing the most effective of these buffers to be the di-peptide carnosine, or beta-alinine/histidine.
This is because carnosine possesses a pKa value of 6.83, which is very close to the body's natural pH level of 7.0. Why is this important? The pKa value is closely linked to how much of the buffer compound can bond with the hydrogen ions. A buffer with a pKa of 7.0 would have only half of its capacity for bonding tied up with protons, leaving an ample 50 percent of its capacity available to bond with the hydrogen.
Dr. Mark Tallon holds a Ph.D. in Muscle Biochemistry from Southampton University in the U.K., and he puts it this way:
"Another way of looking at this is to imagine carnosine as a four-seated car with two people sitting in the front (hydrogen ions), leaving two seats empty in the back to pick up two more people (additional hydrogen ions). Therefore, the more carnosine in the muscle, the more H+ ions we can pick up."
Dr Tallon says that carnosine has been found to be naturally more concentrated in Type II muscle fibres, those that provide 'fast-twitch' muscle ability and have also been found to be more prevalent in top professional bodybuilders (as opposed to Type I muscle fibres).
"This, in theory, might be why it could be easier for them to build more muscular bodies, faster and larger, than the rest of us," Dr Tallon explains. "We also know carnosine is high in the muscles of those exposed to prolonged and low muscle pH (such as diving mammals). This decrease in pH isn't due to lactate per se, as you may have been told in the past, but rather the production of hydrogen ions (H+) as part of the process of energy generation."
Carnosine's (or beta alinine's) ability to delay acidosis is directly linked to its concentration, says Dr Tallon, suggesting that supplementation could play a significant role. In biopsies from elite bodybuilders, studies have shown "a 50 percent increase in whole muscle carnosine, which could be much higher in Type II fibers due to the preferential distribution. This would have a huge impact on performance and resistance to high-intensity fatigue if we could achieve this through supplementation," he says.
"There was also a study…presented at the 2004 ACSM [American College of Sports Medicine…that showed significantly higher mean power during repeated sprints in subjects with higher muscle carnosine concentrations."
He goes on to say that performance data on beta-alanine were presented that demonstrated an increased ability to perform maximal exercise at intensities experienced in the gym.
"In this study, subjects were tested using a maximal bike test and 110 percent of the final power output was calculated. Subjects were then tested at this 110 percent of exercise capacity, and time to fatigue was measured. These subjects were then given either beta-alanine or a placebo and tested again, using the same test at four weeks and 10 weeks. If you look at the data, this study proves unequivocally that beta-alanine supplementation enhances muscle and exercise performance.
More recent findings support the studies Dr Tallon cites. A /www.ncbi.nlm.nih.gov/pubmed/17136505">
study published in Amino Acids, November 30, 2007 by the Department of Exercise and Health Science at the University of Oklahoma found – among other results – a 12.6% increase in fatigue threshold (PWCFT) for young women. In August of 2007, a multi-disciplinary U.K.-Belgian-U.S. study in the Journal of Applied Physiology, used proton magnetic resonance spectroscopy to measure oral beta-alanine supplementation's effect on sprinters, finding:
"carnosine loading slightly but significantly attenuated fatigue in repeated bouts of exhaustive dynamic contractions."
Beta-alinine supplementation would appear to be not only effective but safe, say proponents. According to the website www.betaalanine.info:
"Studies, going up to 12 weeks of continued beta-alanine use, have looked at a large array of blood biochemical, hematological and hormonal markers and no negative changes have occurred whatsoever. While it is impossible to say beta-alanine is one hundred percent safe until longer term studies are complete, we do know that up to 12 weeks of continued beta-alanine supplementation is indeed safe."
We mentioned earlier that carnosine is found in the body naturally. Eating meat can further augment these levels, but as Dr Tallon points out, it might take quite a lot.
"Research indicates that right around 3.2 grams of beta-alanine supplementation, daily, can likely impart the desired benefits. However, this is only achieved after at least three to four weeks of continuous usage...one gram of beta-alanine delivers the same amount of L-carnosine as is potentially available from the ingestion of 80 grams of turkey [meaning] you would have to eat nearly one pound of turkey to achieve the required minimal supplemental dose of carnosine. Would you want to do that three or four times a day?
