Branched Chain Amino Acids

by: David Eackloff


There are 20 standard amino acids present in the human body.  Among these, 9 are characterized as essential amino acids. They are termed essential because they are not synthesized in the human body, instead they must be ingested. In the form of protein, amino acids are the second largest component of muscle cells, the largest being water. Three of these amino acids are name “Branched chain amino acids” (BCAA’s) due to the shape of their chemical bond. These three branched-chain amino acids are Leucine, isoleucine, and valine. Together they are responsible for 35% of the total amino acids that make up muscle protein. Unlike other amino acids that are metabolized in the liver, BCAA’s are metabolized in the muscle cell and can be used to produce energy in the form of ATP. In recent years supplementation of BCAA’s has become popular among athletes for their role in recovery.


During times of high stress to the muscle such as resistance training, metabolism of BCAA’s is heightened. Due to their metabolic properties, BCAA’s have been used as a performance-enhancing supplement because of their ability to deliver quick energy to the working muscles in the form of ATP. BCAA’s can also enhance the performance of long duration exercises because of the way it spares glycogen stores within the muscle.  Studies have shown that ingesting BCAA’s before or during prolonged activity can spare glycogen stores up to 25%.

BCAA’s also have an effect on hormone levels in the body. For athletes, hormones will ultimately determine our muscle size. Athletes want their hormones to produce an anabolic response to the muscle. The most notable anabolic hormones are Testosterone, Human growth hormone, and insulin. BCAA’s have been shown to elevate testosterone levels while decreasing the catabolic effects of cortisol. A study has found that individuals who consumed BCAA’s prior to training maintained elevated testosterone levels post workout with a decrease in cortisol levels. BCAA’s role in elevating testosterones levels and decreasing cortisol levels has been shown to produce an anabolic effect to muscle tissue. In simpler terms more muscle is being built while less is being broken down. An Interesting study from The Journal of Sport Nutrition on the effects of BCAA’s on Delayed onset muscle soreness (DOMS) has shown that individuals who supplemented with BCAA’s during an intensive lowerbody workout consisting of a high volume of bodyweight squats with an eccentric focus elicited less muscle soreness 48 hours post workout than the control group who had not ingested BCAA’s. DOMS are still a misunderstood subject in sports medicine and BCAA’s may be the key to preventing it. Not only do BCAA’s have anabolic properties but they also aid in fat loss. Because most weight loss diets call for a caloric deficit, muscle tissue is often broken down along with fats. Supplementing BCAA’s during a fat loss diet will unsure that muscle mass is maintained while fat is being shed during times of caloric deficit. The maintenance of muscle during a fat loss diet will help the individual burn more calories throughout the day due to a heightened metabolic state, as muscles require a large amount of calories to maintain their size. This is especially evident during a fasting diet when the purpose is to maintain muscle mass while shedding fat.  I should note that consuming BCAA’s prior to fasted training has shown to reduce hunger effects. This may be due to its role in sparing glycogen stores in the muscle.

During exercise our muscles go into a catabolic state as micro-tears are produced within the muscle. It is not until our recovery time when our cells become anabolic. Studies show that to optimize the effects of supplementing BCAA’s, these amino acids should be taken in a total of at least 10 grams pre, intro, and post workout. This will allow for the greatest anti-catabolic affect to the muscle cells. Although these times are optimal for uptake in the muscle cells, BCAA’s can still be taken throughout the day to enhance recovery.


 Out of the three BCAA’s, leucine has shown to produce the greatest increase in muscle protein synthesis. Leucine activates a powerful muscle building pathways named mTOR. mTOR is very sensitive to leucine and in its presence will stimulate protein synthesis. It is unsure why leucine in particular activates the mTOR pathway. Studies have shown that supplementing leucine with carbs and protein post workout has elicited a greater recovery effect than just protein and carbs alone. Many question weather substituting leucine for protein as a post workout supplement will elicit a greater recovery response. This idea is still under debate as new research is emerging.

While there have been no study’s that suggest any long term side effects with supplementation of BCAA’s, some physicians advice not taking BCAA’s before activities with high levels of motor coordination such as driving as some individuals have experienced symptoms of fatigue and loss of coordination. However these side affects are uncommon.


BCAA’s can be found in many natural foods and may not require supplementation if already present in an individuals current diet. With the explosion of the supplement industry many have forgotten that nutrients can be obtained from a natural healthy diet. Below is a table that shows foods with high concentrations of BCAA’s specifically Leucine:

Since it may be near impossible to consume the amount of BCAA’s we want through our traditional diet, supplementation of BCAA’s is common and recommended for athletes. BCAA supplements I would recommend would be those that are high in Leucine. As explained earlier Leucine has shown to be the greatest contributor to muscle protein synthesis as opposed to the other 8 essential amino acids. That being said, the most complete BCAA supplement I have found is Inner Armour BCAA PEAK Leucine loaded. This BCAA supplement contains 11 grams of BCAA per serving, 6.2 grams coming from leucine. This high ratio of leucine is ideal.

With all of the supplements on the market it is hard to tell what is going to give us the best bang for our buck. That being said, BCAA supplements are relatively cheap and effective. They are a great supplement to add to your gym bag and a powerful way to enhance recovery.


Shimomura, Yoshiharu. “Branched-Chain Amino Acid Supplementation Before Squat Exercise and Delayed-Onset Muscle Soreness” International Journal of Sport Nutrition and Exercise Metabolism (2010) 20, 236-244, Accessed July 26, 2013.

Norton, Layne. “Leucine: Build Muscle with this Anabolic Amino Acid” March 1, 2012. Accessed July 27, 2013. <>

Galanis, David. “BCAA’s: The Building Blocks of Muscle” October 6, 2003. Accessed July 27, 2013 <>

“Exercise-Induced Muscle Damage Is Reduced In Resistance-Trained Males By Branched Chain Amino Acids: A Randomized, Double-Blind, Placebo Controlled Study.” Journal Of The International Society Of Sports Nutrition 9.1 (2012): 20-26. SPORTDiscus with Full Text. Accessed July 26, 2013.

Robert R. Wolfe, et al. “Stimulation Of Muscle Anabolism By Resistance Exercise And Ingestion Of Leucine Plus Protein.” Applied Physiology, Nutrition & Metabolism 34.2 (2009): 151-161. SPORTDiscus with Full Text. Accessed July 26, 2013.


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