Branched-Chain Amino Acids (BCAAs) and Aspects of Exercise

Branched-chain amino acids (BCAAs) are the amino acids leucine, isoleucine, and valine. These three amino acids comprise around 35% of the body’s amino acids and about 14-18% of the amino acids found in muscles and are considered essential because your body cannot create them. Instead, you can only get these BCAAs through diet [1].

Regarding their relationship with exercise, many workout enthusiasts consume BCAAs to increase muscle growth, improve exercise performance, decrease muscle soreness, and maintain healthy blood sugar levels. This article will be a review of published scientific studies evaluating BCAAs’ relationship with these exercise aspects.

BCAAs’ Role in the Body

When compared to other amino acids, BCAAs are broken down in the body’s muscles, rather than in the liver like most other amino acids, and because of this, many scientists have developed the relationship between BCAAs and energy production during exercise [2].

Several studies have noted BCAAs play vital roles in protein synthesis and muscle creation, with leucine to represent the most substantial role [3] [4] [5] and isoleucine and valine having stronger functions with energy production and blood sugar regulation [6] [11].

Further, scientists have also found that BCAAs may play a role in regulating blood sugar levels because BCAAs seem to preserve muscle and liver sugar stores and stimulate cells to utilize sugar in the bloodstream [6] [7] [8] [9]. Also, a 2006 study found BCAAs to reduce cognitive fatigue by decreasing the level of serotonin being produced in the brain [10].

Exercise Fatigue

During two studies, researchers found participants had up to 15% less fatigue when given BCAAs during exercise when compared to individuals who were given a placebo [12] [13].

In a 2011 study, researchers set to determine whether BCAA supplementation enhanced exercise capacity and lipid oxidation in glycogen-depleted subjects in a double-blind, placebo-controlled trial. The researchers found BCAA supplementation did increase resistance to fatigue and improve lipid oxidation during exercise in glycogen-depleted subjects, with the BCAA group being able to exercise up to 12% longer than the control group [14].

It is also critical to note BCAAs seem to be more effective in preventing fatigue in individuals who are more untrained in exercise than trained athletes [15].

Muscle Soreness

Several studies also suggest BCAAs may help with muscle soreness after exercise. A 2000 study explained because BCAAs lower the levels of creatine kinase and lactate dehydrogenase, which are enzymes involved in muscle damage, BCAAs may improve recovery and protect against this type of injury [16].

Several randomized, double-blind, placebo-controlled studies found BCAAs to improve protein synthesis and muscle recovery time as much as 33% [17] [18], with one study noting this effect to be particularly useful in women [19]. Also, two studies indicated that patients who were given BCAAs that performed the same exercise 24-48 hours later were able to do so up to 20% better [18] [20]. Yet, these effects seem to be moderated by one’s sex and the amount of protein in one’s diet [19] [21].

Muscle Mass

Many athletes and workout enthusiasts claim to consume BCAAs to help increase muscle mass, and this makes sense because BCAAs play a direct role in building muscle [5].

Specifically, the BCAA leucine seems to be very useful in producing higher levels of muscle when consumed at higher proportions than isoleucine and valine [22] [23]

Though some studies support that BCAAs may help to increase muscle mass with exercise, a 2010 study found whey protein supplementation to be more efficient with building muscle mass [24].

Blood Sugar Regulation

Studies have found BCAAs to support healthy blood sugar levels by increasing insulin secretion because leucine and isoleucine cause muscles to absorb sugar from the bloodstream, which reduces blood sugar levels [6] [25] [26].

However, with a high-fat diet, the opposite has been shown to occur, with BCAA supplementation possibly leading to insulin resistance [27] [28].

Therefore, BCAAs’ effect on blood sugar levels is largely determined by a person’s lifestyle and diet. In a 2012 study, researchers gave BCAAs to 27 patients who had hepatitis C and insulin resistance. Of the 27 patients, HbA1c levels improved in 10 of them, while the remaining 17 either experienced worsened or consistent HbA1c levels [29].

Nevertheless, the research concerning BCAAs and blood sugar regulation is still too slim to draw any definite conclusions.

Weight Loss

Like the relationship between BCAAs and blood sugar regulation, the relationship between BCAAs and weight loss seems to fluctuate person to person largely. However, in some cases, it seems to exist.

In a 2011 study evaluating BCAAs’ effects on body weight, the researchers found an inverse relationship between BCAA intake and obesity [30]. An additional study found supplementary results [31]. These studies found consuming an average of 15mg versus 12mg of BCAAs every day resulted in a 30% reduced risk of becoming overweight or obese. However, diet and exercise still play a paramount role in obesity.

In a 1997 study examining the diets of competitive wrestlers, scientists found athletes who had a restrictive diet high in protein with BCAA supplementation lost 3.5 pounds more than those who were given a soy supplement during the 19 days the study was conducted, and the BCAA group lost an average of 0.6% more body fat [32].


BCAAs seem to have a strong following of exercise and workout enthusiasts who claim the supplement aids their exercise performance, recovery time, and weight loss. In general, while studies do support these claims, an individual’s diet and lifestyle play moderating roles in the effectiveness of BCAAs.

Healthmasters’ Muscle Blast is a great BCAA formula and provides additional amino acids necessary for muscle regeneration.

If you have any questions about Healthmasters’ Muscle Blast, please call our office at 800.726.1834.