Friday, April 6, 2012

Carnosine: Intensity Kerosene? By Jerry Brainum

L-carnosine (not to be confused with L-carnitine) is a dipeptide, or combination of two bonded amino acids. Carnosine has earned a reputation as a nutracuetical because of its potent antioxidant and anti-aging properties. Some research shows that it may blunt glycation, a process that deposits sugar in protein structures, which renders them stiff and weak. Glycation is considered a major cause of the aging process.
Carnosine acts as an intramuscular buffer. That means it can reduce the acidity, or burning sensation, that occurs during and after an intense exercise set, enabling you to train harder. The increased acidity typical of intense weight training leads to a blunting activity of the enzymes required for energy production, the result being fatigue.
      As you might expect, regular intense exercise upregulates the muscle content of carnosine. It’s the body’s way of compensating for the hypoxia, or lack of oxygen, characteristic of anaerobic exercise. The lack of oxygen causes the buildup of excess hydrogen ions and fatigue.
      Carnosine supplements are now available, but just how much can be absorbed into muscle is questionable. An enzyme called carnosinase degrades carnosine into its constituent amino acids, histidine and beta-alanine. On the other hand, a few studies have recovered carnosine in the urine following oral intake, pointing to absorption. Others say that larger doses, such as 1,000 milligrams or more, bypass the carnosinase barrier to some extent—although smaller doses are rapidly degraded by the enzyme.
     Carnosine concentrates in type 2 muscle fibers, which makes sense, since type 2 fibers are employed in intense anaerobic exercise and thus require extra buffering capacity. While carnosine supplements should offer considerable benefits, such as decreased fatigue and the ability to train harder, they may not be the most effective way to increase muscle carnosine.
     You could also take the two amino acids that constitute carnosine, but muscles are already saturated with histidine, and taking it does nothing to increase muscle carnosine content. Beta-alanine, however, is another story. One study showed that providing human subjects with four grams of beta-alanine for one week, followed by an increase to 6.6 grams daily for a month, led to a 60 percent increase in muscle carnosine content. Clearly, beta-alanine is the limiting factor for increasing muscle carnosine levels.
      According to another recent study, however, there is another way to increase muscle carnosine content: Become a bodybuilder.1 The study compared the muscle carnosine content of six competitive-level bodybuilders to six untrained men and found that the bodybuilders had twice as much carnosine as the untrained men.The bodybuilders’ levels of carnosine were estimated to promote a 40 percent increase in muscle-buffering capacity. Exactly why the bodybuilders showed the higher level wasn’t clear. One reason could be the exercise itself, since typical bodybuilding workouts are anaerobic and result in excess acid production. The increased carnosine may be an adaptation to compensate for the higher acid levels that regularly occur with training.
       Other possibilities include dietary supplements. The bodybuilders in the study all used whey, glutamine, casein and branched-chain amino acid supplements. They also used various herbs; however, none of those supplements is linked to an increase of carnosine in the body.
      The bodybuilders also freely admitted to using anabolic steroids. In a recent animal study, providing a dose of testosterone every other day for two weeks resulted in a 268 percent increase in muscle carnosine levels. How steroids do that isn’t clear. It may be just a result of increased muscle mass from steroid use or an increase in the activity of the enzyme that synthesizes carnosine in muscle. Another explanation is increased muscle amino acid uptake, thus providing the precursor building blocks of carnosine.
In the same study the bodybuilders showed 38 percent less taurine than the untrained men. Taurine concentrates in type 1, or slow-twitch, aerobic muscle fibers. As I noted recently in
IRON MAN taurine offers many possible benefits.
      Why the bodybuilders were low on taurine wasn’t clear, although taurine is known to be excreted more rapidly after exercise. In addition, since bodybuilding focuses primarily on type 2 fibers, it may simply reflect an adaptive need of the body, because type 2 muscles need more carnosine.
     Some have suggested that workout efficiency can be greatly improved by taking large oral doses of carnosine. That may indeed work, but carnosine isn’t cheap, and the suggested doses would cost about $5 each. Carnosine can also be injected, but that’s not a likely option for most of us. The best carnosine-loading method appears to use an oral beta-alanine supplement. Interestingly, some preliminary research shows that combining beta-alanine with creatine significantly increases the intensity level of bodybuilding training.
    Don’t take  beta alanine at the same time as taurine supplements. They use the same uptake carrier, and ingesting them simultaneously will cancel out the effects of taurine.

 Tallon, M.J., et al. (2005). The carnosine content of vastus lateralis is elevated in resistance-trained bodybuilders.J Strength Cond Res. 19:725-729.

©,2012, Jerry Brainum.Any reprinting in any type of media, including electronic and foreign is expressly prohibited.

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