Branched chain amino acids include leucine, isoleucine, and valine. They support anabolic muscle-building, provide energy for high-intensity endurance training, and contribute to improved mental function and mood. They are among the nine essential amino acids that the body is unable to make, meaning they must be ingested through food or supplements. BCAA’s are found in high-protein foods such as meat and whey protein.
BCAA’s, as their name suggests, have a branched side chain that makes the job of converting each amino acid into energy during intense exertion easier for the body to accomplish. The more BCAAs that are present in the muscles, the more they will be used for energy. This is beneficial during weight training, or endurance training as it slows the breakdown of muscles cells and serves to prevent catabolism.
At the most basic level, BCAA’s can trigger protein synthesis, increase energy expenditure and have been shown to improve glucose tolerance, which is important because glucose intolerance is a precursor to diabetes. Even when you aren’t training BCAAs will help minimize fat gain and muscle loss from inactivity. This means that on days when you aren’t training, BCAAs are just as important as during and post-workout.
A study in the journal Medicine and Science in Sports and Exercise found that BCAA supplementation can contribute to an anabolic environment in the body. Leucine-enriched BCAA’s was shown to elevate and prolong protein synthesis after resistance training. There was evidence of a dose-dependent response to BCAAs, which is why some suggest taking them before, during, and after training.
BCAA supplementation results in maximal protein synthesis because it increases the intracellular availability of amino acids and activates something called the mTORC1 signaling pathway that is essential for muscle-building. Aging is associated with an impaired ability to activate mTORC1 signaling and protein synthesis. In older individuals, this pathway is not activated to the same extent as in younger trainees after training. This can be somewhat corrected with leucine-enriched BCAA’s are.
Another great benefit of BCAA’s is that if you have to take time off from training, they will minimize muscle loss and fat gain. A study in the European Journal of Applied Physiology found that giving BCAA’s to rats who had their hind-limbs immobilized for six days helped preserve protein synthesis that regulates cell growth. The BCAA’s didn’t completely prevent protein degradation and muscle atrophy in the rats’ hind limbs, but they helped preserve the muscle to a greater extent than a placebo. The BCAA fed rats also had lower body fat levels following immobilization.
Research shows that individuals with a higher BCAA intake in their diets have lower rates of obesity, lower body weight, and better body composition. Researchers suggest that leucine increases energy expenditure and improves glucose tolerance. A review in the journal Aging found that BCAA’s, and in particular leucine, appear to have unique obesity-reducing effects because they decrease food intake and body weight by increasing the gene signaling of the mTOR pathway.
The benefits of BCAA’s for a lean and muscular body were reported in a very large study of 4429 subjects. Those with largest amounts of BCAA’s in their diets were the slimmest, and had significantly less chance of being overweight than those with a lower BCAA intake. Researchers think leucine is the most important amino acid for body composition, although only in conjunction with the other BCAAs—a leucine-enriched mixture is best.
BCAA’s will also help to minimize the cortisol response that comes from heavy weight training. This is ideal because cortisol degrades the muscles and can lead to greater fat gain. Less cortisol means a more favorable testosterone to cortisol ratio that will result in faster recovery and more muscle development.
Two studies show the role of BCAA’s in decreasing muscle protein degradation. A 2010 study found that taking BCAA’s in conjunction with resistance training produces significantly higher testosterone levels than a placebo. Participants in this study who took BCAA’s also had a lower cortisol response. This is important because both strength gains as well as a decrease in protein degradation are more likely to produce a more favorable testosterone to cortisol ratio, than total testosterone levels.
A new study in the Chinese Journal of Physiology tested the effect of a drink of BCAA’s, arginine, and carbs on hormone response and psychological state after a single session of exhaustive exercise. Testosterone was up significantly and the testosterone to cortisol ratio was much more favorable with the BCAA drink than with a placebo. Testosterone was highest at the 120-minute recovery point, indicating a prolonged anabolic effect.
Also, participants were given test to measure psychological condition after the extremely intense workout. Participants who received the BCAA drink recovered much more quickly than the placebo group. The decrease in fatigue score at 120 minutes post-workout was significant only in the BCAA test group.
Additional research compared taking 10 grams of protein that was 18 percent leucine with a similar drink that was 35 percent leucine. The higher leucine concentration resulted in greater anabolic protein signaling, which means less muscle breakdown from the degrading effects of cortisol.
Another British study showed that taking the leucine actually translates into greater strength. Previously untrained participants ingested four grams of leucine a day in conjunction with a 12-week resistance training program and increased strength by 41 percent. A placebo training group had strength increases of 31 percent after completing the same training program. These results were with subjects that were not weight training, so the results that we would see would likely be relatively minor in comparison.
Make sure you check back later for the follow-up to this article, and more information on branched chain amino acids.
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