Wheying the Benefits of BCAAs in Exercise

Andrew Reynolds and David Appleby

After hitting the gym, playing sports, or even going for a run, many athletes turn to protein and amino acid (AA) supplements to enhance muscle recovery and growth. Multiple studies suggest that individuals who regularly exercise or partake in high intensity training require more dietary protein and AAs than sedentary individuals. This additional protein not only allows the human body to repair itself, but is also required for everyday metabolic activities and immune function. Of the twenty amino acids that comprise muscle protein, nine are considered essential amino acids. These essential AAs are not able to be produced by the body on its own, and therefore must be ingested through one’s diet. While it is possible to obtain the necessary protein and nutrients through a regular balanced diet, evidence shows that supplementation before and after exercise may prove advantageous. Among the most popular and cost efficient are powdered proteins, found most commonly in the form of whey and casein. Whey protein, often referred to as “fast” protein, has been shown to elicit a sudden, rapid increase of plasma amino acids following ingestion, providing immediate delivery to the body. Casein, however, is known as “slow” protein and induces a rather progressive and prolonged increase in plasma amino acids. While the digestion of these different proteins has been found to mediate protein metabolism and synthesis after exercise, it is debated whether the use of branched-chain amino acids (BCAAs) augments these processes on its own.


The branched-chain amino acids make up approximately one third of skeletal muscle protein in the body, and account for three of the nine essential AAs. Of the three BCAAs are leucine, isoleucine, and valine, which have laid the foundation for a multi-million dollar industry of nutritional supplements. Distributors of BCAA supplements rave of their anabolic capabilities and claim of their role in muscle recovery when taken post-exercise, particularly in regard to leucine. Leucine has been said to not only act as a precursor for muscle protein synthesis, but also a regulator of intracellular signaling pathways involved in the process of protein synthesis. A few studies have reported that the ingestion of BCAAs increases protein balance either by decreasing the rate of breakdown, increasing the rate of synthesis, or a combination of both. Additionally, it was observed that pairing leucine supplements with carbohydrates and protein before and after workouts led to a heightened level of protein synthesis in the body when compared to trials where leucine was not present. However, the credibility and repeatability of the research behind these claims is unclear, and has been rebutted by other scientific studies.

In this study assessing BCAAs and muscle protein synthesis in humans, the idea that BCAAs alone are capable of promoting muscle anabolism is questioned. This claim has been put forward for more than 35 years, but has been chiefly recorded in rat and other animal studies, with almost no studies being conducted regarding the response to oral consumption. The study involves a detailed literature search, and evaluates the theoretical and empirical data used to make these initial claims regarding BCAAs. It discusses how skeletal muscle in humans comprises a much larger portion of total body mass than in rats and therefore leads to several differences in the way muscle protein synthesis is regulated. Another problem with these previous studies is that they often use the “flooding dose” technique, which involves the administration of an amino acid tracer over a very short time period, therefore neglecting any possibility of sustained effects. With that being said, many of the results found in past experiments employ methods that make the extrapolation of the data to humans unfitting and reduce the physiological significance. In addition, this study displayed how only two studies were conducted analyzing the intravenous effects of BCAAs in humans, noting in both that BCAAs decreased both muscle protein synthesis and protein breakdown. However, the rate of the catabolic processes that broke down muscle protein exceeded the rate of protein synthesis in both cases during BCAA infusion. Due to these findings, the researchers refuted the claim that consumption of dietary BCAAs initiates anabolic activity and increases muscle protein synthesis.

Overall, it is evident that additional attention to diet and supplementation is essential for athletes and individuals who regularly exercise in order to promote the growth and repair of muscles, and to maintain a healthy body. While use of protein powders in the role of muscle protein synthesis has been backed by extensive scientific research, it is still unclear of the extent to which BCAAs are capable of carrying out these same processes on their own. More studies need to be conducted in human subjects observing the activity and metabolism of proteins when dietary BCAAs are ingested to better determine the effectiveness of their use. Many factors come into play when assessing the best supplements to take in regards to exercise, including intake quantity, timing of ingestion, and interaction effects. After observing the conflicting research claims, the use of BCAAs alone may not yield noticeable results, but seems to have little to no risk involved in taking them. Many trainers and workout regimens advise the combination of protein supplements and BCAAs to maximize benefits, but the scientific research is still lacking.

Questions to Consider

  1. What would happen if an individual took more protein supplements/BCAAs than the body needed?
  2. How could studies be better designed to assess the role of BCAAs in humans?

Further Suggested Reading

[1] https://www.ncbi.nlm.nih.gov/pubmed/20048505

[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5568273/

[3] https://www.ncbi.nlm.nih.gov/pubmed/16365096/

[4] https://jissn.biomedcentral.com/articles/10.1186/1550-2783-4-8

[5] http://healthyeating.sfgate.com/primary-role-protein-diet-3403.html

Effects of Protein Supplements on Muscle Recovery and Performance

Many athletes and active individuals often seek the assistance of protein supplements post-exercise for a variety of reasons. Some take them in an effort to increase physical performance, while others aim to reduce muscle soreness and enhance the recovery process. However, the majority of these individuals decide to buy and consume these supplements based on marketing claims that are not backed by scientific research. This article outlines a literature study that examines the correlation between protein and the enhancement of muscular performance and recovery. The study takes into consideration healthy adults under the age of 50, and evaluates the effects of these supplements alone or in combination with carbohydrates on varying performance metrics.The results indicated that the continued use of protein supplements significantly reduced muscle damage and soreness after training sessions, and led to a particular increase in physical performance when participants were negative in nitrogen and energy balance.1 Other studies confirm the benefits of protein supplementation on muscle recovery and performance post-exercise, but at different degrees and with varying limitations.

This article relates to the course because it describes a study and application of the research process that addresses exercise-specific responses to physiological changes. Not only does it discuss and define the metabolic changes that arise from the use of protein supplements, but it also mentions the measurement of exercises and performance for comparison. It details a systematic approach to evaluating a problem through the collection of data, data processing, statistical analysis, evidence based results, and consideration of limitations.

Over the past few years, I have experimented myself with different protein supplements and exercise regimens to observe the potential effects on muscle growth and recovery. Although there are numerous factors that come into play, I agree with the claim that supplements are beneficial when used appropriately. However, diet, degree of activity, and frequency of use lead to large degrees of variation and pose a major limitation when comparing use among individuals. Regardless, much research should be carried out when deciding which protein supplement will be most successful for you and in achieving your goals.

Works Cited

[1] Pasiakos SM, Lieberman HR, McLellan TM. Effects of protein supplements on muscle damage, soreness and recovery of muscle function and physical performance: a systematic review. Sports Med. 2014 May;44(5):655-70. doi: 10.1007/s40279-013-0137-7. Review.

No Whey? No Problem!

In today’s world of social media “fitspo” blogs and fad diets are at our fingertips more than ever.  The “recommended page” on Instagram, for example, is full of fitness bloggers telling you exactly what to eat and what work outs to do for the best results.  And while their advice is often based on some truth, it is also can be blown out of proportion or can be easily misconstrued.   It is important to remember that diet is based on individual needs and that what works for one person may not work for you- therefore, the best way to choose new meal plans is through education. First off, why are proteins so important?

Figure 1: 9 essential amino acids we must ingest.

Proteins have four layers of structures that all play a role in how they work and  how they interact. The primary structure, is simply the sequence of amino acids (AAs) in a polypeptide chain.  There are essential AAs that we must ingest, non-essential AAs that our body can produce, and conditional AAs that are pertinent in times of stress and illness. Protein is extremely beneficial and unarguably critical to our diets, we excrete excess amino acids, so over eating protein poses to additional benefit.

So knowing this, how do you decide how much protein you should eat? Maybe to some surprise, science have shown that athletes actually require the same general range of protein intake when compared to sedentary persons of the same sex. According to the U.S. and Canadian Daily Reference Intakes,  0.8 g·kg−1 of protein is enough to meet the needs of 98% of healthy adults. “There is not a strong body of evidence documenting that additional dietary protein is needed by healthy adults who undertake endurance or resistance exercise, the current DRI for protein and amino acids does not specifically recognize the unique needs of routinely active individuals and competitive athletes.” They also suggest that for adults 18 years and older,  10%-35% of total caloric intake should be comprised of protein. This supports the accepted ideal that the recommended intake levels can be met through regular diet and without supplementation.

What does this mean for those trying to lose or gain weight? Whilst, in both of these cases, it may be easy to fall victim to one of the fad diets, you should take the time to understand them and to find the truth behind them.  CrossFit is currently one of the most popular fitness plans and many of their athletes use meal templates to guide them in fueling their bodies. The Paleo Diet and Zone Diet are two of the most common choices for these athletes, or a combination of the two.  Paleo (sometimes called the caveman diet) is bases on eliminating processed food and eating a high fat, moderate protein and low carb diet. The Zone Diet is based on “blocks” where you eat a specific number of daily servings of proteins, carbohydrates, and fats.  The “blocks” are structured throughout the day rather than in the normal 3 meals a day.  The diets claim to increase metabolism and when tailored to specific goals, can result in significant weight loss and muscle development.

Figure 2: The 40/30/30 breakdown of the Zone Diet.

Samuel N. Cheuvront found that the Zone Diet does not result in the promised outcomes. He found that any significant contribution of active muscle oxidation was not even found in skeletal muscle.  In another investigation by Tipton, et al,  they looked at the differences between ingesting protein (such as whey protein supplements) before weight training versus after. Their results allowed them to conclude that the timing of supplementation does not matter but that having protein in your system consistently does have positive impacts.

Based on the review of the current literature, the biggest conclusion that can be made is that protein does play a large role in diet and in over all health.  What cannot be confirmed is the benefits of protein supplements or high protein diets. According to daily recommended intakes,  it is much more important to have a balanced diet, and the main benefit of a high protein diet may actually be limiting sugar and carb intake.


Further Reading

Orders of Protein Structure

Nutrition and Athletic Performance

Role of Protein in Diet

A Review of Protein Recommendations for Athletes


Questions to Consider

  1. How cognizant are you of your protein intake? Do you stagger it throughout the day?
  2. Have you tried any high or low protein diets? Did you notice any difference in your workouts?
  3. What, if any, do these conclusions have on vegetarians?