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BCAAs prevent swimmers' muscles from breakdown

It's not only strength athletes that benefit from supplements containing branched-chain amino acids [BCAAs]. BCAAs also protect swimmers' muscles, nutritionists at National Taiwan Normal University discovered.

BCAAs prevent swimmers' muscles from breakdown


BCAAs prevent swimmers' muscles from breakdown


BCAAs prevent swimmers' muscles from breakdown


There are three BCAAs: leucine, iso-leucine and valine [the structures of all three are shown here]. Companies have been selling supplements containing BCAAs for years, claiming that they protect muscle tissue from being broken down during exertion. Muscles consist for 35 percent of BCAAs, but also like to use BCAAs as fuel. If you take extra BCAAs, you prevent muscle cells from converting their own proteins into energy.

The Taiwanese wanted to know whether BCAA supplements would help swimmers perform better, so they did an experiment with 19 male students aged between 19 and 22. The students swam moderately intensively for one and a half hours every day.

For a period of two weeks, the subjects took 4 g BCAAs three times a day, a daily total of 12 grams. The researchers then repeated the procedure on another occasion, but gave the students a placebo. At the end of the supplementation or placebo period the subjects had to swim freestyle for 25 minutes, covering as great a distance as possible. Then they had to swim 600 m in as short a time as possible.

When the body converts amino acids into glucose and then this glucose into energy the muscles release more amino acids. The amino acids released consist for 85 percent of glutamine and alanine. The researchers noticed that taking a BCAA supplement on the day that the subjects did intensive exercise lowered the concentration of the amino acids.

Measurement 3 was done on the day of the exertion tests, but before that the subjects had undertaken exercise. Measurement 4 was taken after 25 minutes of swimming. Measurement 5 was taken later in the day, after the subjects had swum the 600 m. Measurement 6 was taken on the day after the exertion tests.

BCAAs prevent swimmers' muscles from breakdown

BCAAs prevent swimmers' muscles from breakdown

Hydroxyproline is a metabolite of proline, an amino acid found primarily in the collagen of connective tissue. It is an indicator of cartilage breakdown. 3-Methyl-Histidine is an indicator of muscle tissue breakdown.

BCAAs didn't improve the swimmers' times, and did not make them more muscular.

"The 15 days of BCAA supplementation might reduce muscle proteolysis induced by intense exercise", the researchers conclude. "The mechanism might be due to the availability of ammonia provided by supplemented BCAA oxidation during exercise. Without the supply of exogenous BCAAs, muscle might have to rely on endogenous BCAAs to fulfill the energy demands."

More studies
In 2000 Australian sports scientists published the results of a similar study, in which the test subjects were given 12 g BCAAs or a placebo for two weeks. On day 12 they had to cycle for 2 hours at 70 percent of their VO2max. [J Sports Med Phys Fitness. 2000 Sep; 40(3): 240-6.] The supplement inhibited an increase in the enzymes creatine kinase and lactate dehydrogenase, both of which are indicators of muscle breakdown.

According to a 2007 study, BCAA supplementation only on the day that intensive exercise is done also has an effect. [Int J Sport Nutr Exerc Metab. 2007 Dec; 17(6): 595-607.] In this experiment untrained subjects had to cycle for 90 minutes at 55 percent of their VO2max. Before and after the session the subjects were given 25 g BCAAs or a placebo. Taking the supplement inhibited the increase in creatine kinase and lactate dehydrogenase. Moreover, the test subjects experienced less muscle soreness and regained their strength more quickly.

J Am Coll Nutr. 2006 Jun;25(3):188-94.

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