The essential branched chain amino acids (BCAA's) including leucine, isoleucine, and valine are of special importance for athletes because they are metabolized in the muscle, rather than in the liver (26). Theoretically, after digestion, once protein is broken down into individual amino acids, these amino acids can either be used to build new proteins or be burned as fuel to produce energy. If the athlete's diet is adequate in nutrition, then the above "essential" amino acids will be used for protein synthesis which is optimal for advanced human performance. It should also be noted that, essential amino acids are not produced in the body such as non-essential amino acids, but rather obtained through proper nutrition. Therefore, it is often theorized that the supplementation of BCAA's are of essential importance to athletes due to their ability to alleviate any deficiencies that the body alone cannot produce. BCAA's have also been known in reducing fatigue in both anaerobic and endurance sports. It has also been noted that leucine may be the most critical BCAA because of its anti-catabolic properties and vital role in protein synthesis (83).
BCAA's have a great deal of thorough and conclusive research surrounding them. Although there are a few studies which show mixed results, it should be noted that most studies seem quite favorable in regards to the supplementation with BCAA's. In a study performed by Ohtani et al (27), the results showed that the subjects who received BCAA's had a significant increase in exercise efficiency due to the heightened levels of aerobic and anaerobic capacity as compared to the placebo group.
Other studies of similar characteristics of supplementing with BCAA's have also been consistent with the above results. For example, in another study performed by Ohtani et al (29), a thorough before and after analysis concluded that markers for physical conditioning, fitness, and endurance greatly improved. In fact, only 2.2 g of the amino acid mixture three times a day significantly improved other physiological markers such as: red blood cell count, hemoglobin, hematocrit, serum albumin, fasting glucose, and a decrease in creatine phophokinase (p<0.05), suggesting increased hematopoiesis and glycogenesis, and rapid alleviation of muscle inflammation by the amino acid mixture. All of these beneficial factors may be of huge significance in high performance athletes especially in terms of overall conditioning.
Another study by Sugita et al (28) demonstrated the effect of an amino acid mixture, mainly consisting of BCAA's on recovery from muscle fatigue and damage after eccentric exercise training. Twenty-two male college students were given 5.6 grams of the amino acid mixture twice daily which resulted in a faster recovery of muscle strength than that of the placebo group. The oral ingestion of the amino acid mixture was proved to be effective for muscle strength recovery after the eccentric exercise.
Perhaps, one of the most profound studies on amino acid supplementation to date was done by Kraemer et al (30) in which 17 trained men randomly assigned to either an amino acid group or a placebo group underwent a 4 week training routine of total body resistance training. The first two weeks of training was an overreaching stage in which the total volume of training was relatively high which was then followed by a two week period of tapering or less total volume. Before any of the training took place, there were baseline measurements taken to determine strength, such as 1RM bench press and squat as well as a ballistic bench press and jump squat to determine power output.
The results in this study were quite interesting. First of all, it appears that both groups had significant increases in strength, power, and resistance to fatigue after the entire four week period which can be attributed to the training program. This would support the fact that overreaching can be very beneficial to athletes trying to improve performance. However, the interesting results show that the placebo group experienced significant decreases in strength in the first 2 weeks of the training program where the subjects were in a stage of overreaching. However, the amino acid group did not have any change in performance during this period. This was obviously due to the anti-catabolic effects that BCAA's promote in the body. Thus, for athletes interested in peaking performance, through the use of strenuous and intense exercise where initial decrements of performance can occur, these negative symptoms can be regulated and possibly negated by the supplementation of BCAA's.
BCAA's have a positive effect on reducing fatigue and help in maintaining plasma levels of BCAA's in the body. Coombes et al (84) examined the effects of branched-chain amino acid (BCAA) supplementation on serum indicators of muscle damage after long periods of exercise. They hypothesized that BCAA supplementation would reduce serum indicators of muscle damage. There were 16 healthy males randomly assigned to either an experimental group in which they supplemented with 12 grams of BCAA's a day or a control/placebo group. Both groups participated in a two hour cycling activity at an intensity of 70% VO2. The results of this study clearly show that BCAA supplementation played a significant role in reducing levels of plasma markers associated with muscle tissue damage after intense endurance exercise. Of further interest, there have been many other studies similar to this in which plasma levels of specific compounds indicating muscle damage were reduced with BCAA supplementation. Low amounts of BCAA plasma levels, specifically leucine, have been correlated with increased levels of fatigue and reduced markers of physical performance (85).
Another interesting function of BCAA's is their profound effect on clinically diagnosed patients with specialized diseases or health problems. First, BCAA's may support liver health in patients with liver disease (31). Also, patients suffering from amyotrophic lateral sclerosis, or ALA, may show improvement after using BCAA's (32). Third, BCAA's may help support health and recovery in patients who have experienced trauma, extreme physical stress, kidney failure, and burns (33). Finally, BCAA's may aid in recovery after surgery (34).
Dosage recommendations for BCAA's vary widely and more research is needed before finalization is made for the best supplementation dosage of BCAA's. However, the most recent research indicates that dosages typically range from 200-300mg of each BCAA daily to 2-5 grams of each daily. It however seems that the smallest beneficial dosage of BCAA's is 150mg of each leucine, isoleucine, and valine daily (35).
Summary and Recommendation
Although there may be slight contradictions in pre-existing research regarding BCAA supplementation, there is enough positive scientific evidence to warrant its usage in high performance athletes. From numerous studies, it is clear that BCAA's have a significant role in increasing overall conditioning factors such as aerobic and anaerobic capacities, by improving physiological markers such as: red blood cell count, hemoglobin, hematocrit, serum albumin, fasting glucose levels, a decrease in creatine phophokinase, increased glycogenesis, and even rapid alleviation of muscle inflammation. Other positive attributes associated with BCAA's as shown by current scientific literature includes: increased muscle recovery, especially after intense eccentric exercise, alleviation of short term decrements in performance commonly associated with overreaching, improvements in plasma levels of BCAA's (often linked with fatigue), and may aid in the healing of injuries, sickness, and trauma. There may also be strength and muscle mass increases accompanied by BCAA supplementation. However, further research is needed to determine whether this is a direct or indirect effect of BCAA supplementation.
According to consumerlab.com, there is no apparent toxicity or danger associated with BCAA supplementation. ConsumerLab also recommends anywhere from 1-12 grams. The typical ratio of BCAA's is 50% leucine, 25% isoleucine, and 25% valine. This also lines up with the most current research on BCAA supplementation. BCAA's should be taken with water before and after training with any other pre or post workout supplement.
According to consumerlab.com and other valid sources, some of the best BCAA products include: Iron-Tech, Essential Liquid Amino Complex, AST BCAA, MRM BCAA+G, Precision Engineered BCAA, Beverly International Muscularity, Optimum Nutrition BCAA, Controlled Labs Purple Wraath, and Ultimate Nutrition BCAA.
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