Amino acids. Part II

No sportsman has never heard of BCAA. They are proposed in every way and with the most imaginative slogans, often in association with visibly retouched photos; You can easily buy them in pharmacies, in supermarkets and gyms.

BCAA is the acronym for branched-chain amino acid, which includes three of the nine essential amino acids: leucine, isoleucine and valine. Under normal conditions, a healthy, varied and balanced diet is sufficient to provide the right amount of these nutrients. However, there are cases in which it may be necessary to take them also through supplements (a supplement is a product taken over the regular diet to encourage the intake of certain nutrients).

The use of BCAA-based supplements has been the subject of intense discussion, especially between the 1970s and 1980s, in particular for the treatment of patients with hepatic impairment; because the BCAA present in the muscles are rapidly catabolized in alanine and glutamine in response to the stress. Only afterwards during the 70s athletes have begun to take them. The BCAA act directly on muscular level, preventing the catabolism of the skeletal muscle by slowing down the depletion, or reduction, of the muscle tissue. Indeed after an intense exercise, the level of BCAA in the blood tends to decrease between 10% and 30%, and a good integration can prevent the depletion of muscle proteins and speeds up the consequent recovery.

Recent research has highlighted the importance of the BCAA especially for endurance activities or in training sessions that last more than 60 minutes as the ketoacid produced by the BCAA acts on average within 180 minutes of its intake, which is why it is recommended to take BCAA before training. However, other research has stressed the importance of BCAAs in determining a reduction in the sensation of fatigue during exercise. Indeed, the central fatigue is influenced by an increase of the amino acid tryptophan in the central nervous system, its presence leads to an increase in the production of serotonin (a neurotransmitter that affects the sensation of pain). The passage of tryptophan from the blood to the brain through the blood-brain barrier (Figure 1) occurs thanks to a transport system shared by tryptophan and the BCAA.

Figure 1. The passage of tryptophan from the blood to the brain through the blood-brain barrier

So an increase in the blood concentration of BCAA results in a reduction of the levels of tryptophan that can reach the brain causing a decrease in the production of serotonin and a decrease in the sensation of fatigue. Regarding peripheral fatigue, it has been found that BCAAs cause oxidation of substrates during high-intensity workouts, especially when the muscles have low glycogen levels. To date, studies have not shown that BCAA are used directly by our body to produce energy, in fact, from their oxidation comes 1% of the total energy used during the exercise.

The functions of the BCAA are then multiple: from the slowing down of the muscular degradation to the intervention on the perception of central and peripheral fatigue. They can be taken before, during or after training with different functions depending on individual needs.

It should be now clear that:

• If taken before (maximum 90 minutes before working out) there will be an improvement in performance, due to a lower perception of fatigue, and a slowing of muscle depletion

• If taken during a training session they could lead to a decrease in muscle depletion

• If taken after a workout they will speed up the muscle recovery phase.

However, the recommended doses should not exceed 5 g per day, even if for many sports you get to take more than 1 g of BCAA every 10kg of body weight (so a person of 70kg will take 7 g of BCAA per day). We must not forget that an excessive intake of amino acids and proteins both from food and supplements is harmful to the body, in particular in liver and kidney function.

It should be clear now that these products are not suitable for all athletes, because those who practice physical activity occasionally, for example, three times a week for a total of about 3 hours, it can very recover entirely with all the nourishment from a healthy and balanced diet.

References

Franchini A, Romagnoli R. Il mercato degli integratori. Legislazione, vendita, comunicazione. Maggioli Editore. Santarcangelo di Romagna (RN) 2010.

Hsu MC, Chien KY, Hsu CC, Chung CJ, Chan KH. Effects of BCAA, arginine and carbohydrate combined drink on post-exercise biochemical response and psychological condition. Chin J Physiol. 2011.

Shimomura Y1, Murakami T, Nakai N, Nagasaki M, Harris RA. Exercise promotes BCAA catabolism: effects of BCAA supplementation on skeletal muscle during exercise. The American Society for Nutritional Sciences 2004.

Wolinsky I. Nutrition in Exercise and Sport, Third Edition.

Ronald J. Maughan and Robert Murray. Sports Drinks: Basic Science and Practical Aspects (Nutrition in Exercise & Sport). CRC Press, 2000.

Campbell B. Spano M. NSCA’s Guide to Sport and Exercise Nutrition. National Strength and Contitioning Association.

Michele M. Gottschlich, M. Patricia Fuhrman, Kathleen A. Hammond and Beverly J. Holcombe . The Science and Practice of Nutrition Support: A Case-Based Core Curriculum. American Society for Parenteral and Enteral Nutrition 2000.

Ronald J. Maughan. Nutrition in Sports. Blackwell science. Oxford 2000.

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