catabolism
caffeine (in the form of coffee or pills) and/or Branched Chain Amino Acids (pill form).
Several studies have looked at the effects of supplementing the diet with excess BCAAs to determine if there are any benefits for exercising athletes.
It is known that high levels of BCAAs in the blood can reduce the amount of serotonin (a neurotransmitter used by the brain) in the brain.
Researchers also have found a link between serotonin and its ability to cause fatigue including a decrease in
muscle power output (1, 2, 3, 4).
So, researchers hoped to delay the onset of fatigue and improve athletic performance by supplementing the diet of athletes with excess BCAAs (5). One study found that consuming a drink during game time which contained 10 grams of BCAAs improved alertness and mental performance in a group of soccer players (6).
However, a follow-up study found that as much as 18 grams of BCAAs did not delay the amount of time to fatigue while riding exercise cycles (7).
These conflicting results make it difficult to determine if BCAAs can influence fatigue and indicate that more studies need to be done on this issue.
Researchers have looked at other effects of BCAAs than simply fatigue. Several studies showed some very interesting results from BCAA supplementation.
One study found that marathon runners, who must certainly be the most catabolic of all athletes, had significantly higher insulin and testosterone when supplementing with 10 grams of
BCAAs (8). This result suggests that BCAAs may reduce some of the catabolic effects associated with intense exercise.
Several promising studies have shown that BCAAs have the ability to reduce or limit protein breakdown.
Supplementation with BCAAs have been shown to
suppress the use of amino acids for energy (16). If the AAs are not used for energy, then they are more likely to be retained within the muscle rather than burned for fuel.
Other studies looked at the effect of BCAAs on swimmers who were in an overtrained state (17, 18). Those swimmers who supplemented with 2.175 grams of BCAAs were less likely
to be in an overtrained state based on several parameters including lower cortisol, an increase in lean body weight while body fat was lost, and possibly an enhanced immunity to infection.
Another study found that the protein breakdown that is often associated with hiking at high altitudes was decreased following supplementation with BCAAs (19). Those receiving the BCAA supplement consumed 5.76 grams of leucine per day, 2.88 grams of valine per day and 2.88 grams of Isoleucine per day resulting in a 1.5% gain in lean body mass and a 11.7% decrease in body fat while the placebo group lost both muscle and fat which is most common for people in catabolic states.
Another study (21) found that supplementation with 77
mg/kg (7.7 grams for a 100 kg person) of BCAAs 20 minutes before exercise results in better nitrogen (AA) retention in muscle and that BCAAs block the breakdown of muscle proteins. All of these results are very positive for any athlete hoping to maintain an anabolic, growing and healthy state while avoiding a catabolic state of overtraining that can lead to the loss of lean body mass.
What do these results tell us about the biochemical effects of
BCAA supplementation? During exercise, the BCAAs are taken up by muscle cells to produce more energy. These BCAAs are taken from proteins in other regions of the body so that the muscles can continue to work. This loss of BCAAs from other tissues causes a very catabolic and stressful condition, especially for the immune system.
Supplementing with excess BCAAs can reduce this catabolic and stressful situation. A further anticatabolic effect is seen in the hormonal patterns following BCAA supplementation. Some athletes have shown elevated testosterone levels following BCAA supplementation.
In addition, some studies have found enhanced athletic performance in endurance athletes following BCAA supplementation. However, these studies are very preliminary and will require further replication.
BCAAs are found in all animal protein sources with milk being one of the best natural sources of BCAAs. Whey protein is very high in BCAAs and is one of the major reasons that athletes prefer supplementing with whey protein.
Whey is a watery part of milk that separates out as the milk sours and thickens (don't try this at home).
Whey protein is found in cottage cheese along with other milk
proteins. In addition, many companies produce whey protein powders that can be mixed with water or milk.
In all of these studies the amount of supplemental BCAAs ingested ranged from 2.2 grams to 18 grams per day. These are BCAAs consumed above and beyond those obtained from dietary sources and they were usually consumed all at once or during exercise.
In addition to the BCAAs obtained from dietary sources, athletes would benefit by taking an additional 10 grams of BCAAs each day. The ratios of the three BCAAs averaged 40% leucine, 30% valine and 30% isoleucine across all these studies. There is general agreement that leucine is more important than the other two, but this does not negate their importance either.
Studies looking at leucine alone and valine alone
have found similar effects on hormonal profiles. More studies are
necessary to determine the importance of each individual amino acid.
Even though the most appropriate ratio of the BCAAs is unknown
athletes would do well to take them in the 40:30:30 ratio. Animal
proteins are typically 15% BCAAs while whey protein is composed of 30% BCAAs.
For those athletes who are prone to store body fat, they
should consume their supplemental BCAAs with other protein sources, or as a component of whey protein to minimize the effects of insulin. Those athletes who find it difficult to put on any mass (fat or muscle) should consume their BCAAs either alone or with a small quantity of carbohydrates to maximize the effects of insulin. The BCAAs can be consumed during or prior to exercise.
Every athlete should pay attention to the quantity of BCAAs in their diet. BCAAs are a simple and effective way to gain an
anticatabolic edge in the fight for muscle growth and improved strength.
References:
1. Blomstrand et al., Acta Physiologica Scandinavica 133: 115-121, 1988
2. Newshoolme et al., Medical Sports Science Vol. 32: 79-93, 1991
3. Rang and Dale, Pharmacology, pp. 80-92, Churchill Livingstone, Edinburgh, 1987
4. Young, The Clinical Psychopharmacology of tryptophan. In Wurtman and Wurtman, Nutrition and the brain: 49-88, Raven Press, New York,1986
5. Newsholme and Blomstand, Experientia 52(5):413-5, May 15, 1996
6. Blomstrand et al., Acta Physiologica Scandinavica 143: 225-6, 1991
7. van Hall et al., Journal of Physiology 486(pt 3): 789-94, Aug 1, 1995
8. Carli et al., Occupational Physiology 64: 272-77, 1992
9. Castellino et al., Journal of Clinical Investigation 80:1784-93, 1987
10. Fajans et al., Recent Progress in Hormone Research 23:617-23, 1967
16. Blomstrand et al., European J of Applied Physiology and
Occupational Physiology 63:83-8, 1991
17. Kreider, SE American College of Sports Medicine Abstracts, vol. 20 p. 45, 1993
18. Kreider et al, Medicine and Science in Sport and Exercise
25:S123, 1993
19. Schena et al., European J of Applied Phys and Occupational Phys 15(5):394-8, 1992
21. MacLean et al., American J of Physiology, 267(6 pt 1):E1010-22, 1994
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