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

How It Works: Heart Rate Monitors

By: Margot Farnham, Juliana Gullotta & Nicholas Ruggiero

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Can Altitude Masks Improve Athletes Efficiency in Utilizing Oxygen and Increase Athletic Performance?

Eric Bartholomew and Joe Yovanovich

Altitude training has been shown to give athletes a competitive edge by increasing VO2 max, endurance performance, and lung function. The “live high-train low” method as been adopted as one of the most beneficial training methods. By athletes living high and training low, they get the benefits of altitude acclimatization which increases their performance on sea level. As the human body reaches altitude of around 2,100 m, the saturation of oxyhemoglobin decreases significantly. However, a long-term adaptation of living at high altitude is that your body starts to accomodate for the lack of oxygen. By exposing the body to hypoxic conditions, the body will increase its red blood cell (RBC) production as close to 30-50%. This increase in RBCs, increases the oxygen carrying capacity as sea level which will lead to a higher VO2 max, and an increase in athletic performance.  An easy and accessible way to simulate altitude training is through the use of altitude training masks.  

Elevation Training Mask

Many products have been put on the market in order to simulate high altitude training while training at sea level. One of these products is the “Elevation Training Mask” (ETM). The ETM covers both the nose and mouth, using different sized opening and fluxed valves in order to increase resistance of respiration in hopes of increasing VO2 max and lung function. The resistance system in the masks allows the user to stimulate altitude ranges from 914m to 5486m. But in order to truly stimulate a hypoxic state, the masks would have to be able to decrease the partial pressure of oxygen, questioning if ETMs can truly simulate high altitude training and help with overall performance.

In this study, they tested to see the effects of wearing the ETM on endurance performance variable to conclude if ETMs can act as altitude simulators. Using two groups (a control and those using masks), twenty five subjects completed two, 30 minute, high-intensity workouts per week for 6 weeks. Before and after the 6 week training period, VO2max, ventilatory threshold (VT), peak power output (PPO), respiratory compensation threshold (RCT) and maximal heart rate (MHR) were measured in all subjects. The results are shown in Table 1.

Table 1: Changes in Performance Variables

There was significant improvement in VO2max and PPO in both the control and mask groups. Only the mask group had significant differences in VT, Power Output (PO) at VT, RCT and PO at RCT but improvements in VT and PO at VT did not reach statistical significance (VT p=0.06, PO at VT p=0.170). This study was a well executed study, including  pilot testing and constant monitoring of each subject. A limitation of this study is that the subjects volunteered to participate in the study who claimed they were moderately trained. However, the mask and control groups were similar in age, height, weight and BMI at the start of the study.  This decreased the amount of variability in the study. Also, the 6 week training period was titrated based on subjects RPE. RPE is a very subjective way to measure intensity and is not always seen to be the most accurate. This however would not skew results significantly. With all this in mind, it is safe to say that the conclusions made from this article are valid. From this study, we can conclude that wearing an EMT during high-intensity workouts does not appear to act as a simulator of altitude, but more like a respiratory muscle training (RMT) device.


The next study, completed at Lindenwood University is a follow up to the previous study to try and determine if the EMT functions as a RMT device. The study was comprised of 20 recruited resistance-trained men to track the acute effects of the EMT in regards to resistance exercise and maximal effort sprint performances, as well as overall metabolic stress. Baseline testing was completed 3-7 days before the subjects experimental results were obtained. These tests were used to determine the subjects body composition and to assess their 5-repetition maximum (5RM) for bench press and back squat after they were appropriately familiarized with the equipment (bench press, squat rack and non-motorized treadmill). Two trials for all subjects were completed on non-consecutive days with and without the mask (EMT and No Mask (NM) conditions, respectively). The subjects were to complete a bench press and back squat (using weight based off their individual 5RM), as well as a 25-second all out sprint test. Velocity of the bars for the bench and squat tests were determined using a linear position transducer (accuracy correlation coefficient of 0.97). Blood samples were collected to determine blood lactate and oxygen saturation was determined using a finger pulse oximeter.  ANOVA was used for statistical analysis to compare the EMT and NM conditions. Peak velocity of the bench press and back squat were significantly greater in the NM trial (both p = 0.04 < 0.05). Blood lactate was higher in the NM condition for the bench press and sprint test (p < 0.001). Using a 5-point Likert scale to the subjects self-selected their energy, fatigue, alertness and focus for both conditions. The EMT surprisingly did not differ significantly from the NM condition. It should also be noted that 3 subjects were unable to complete the protocols using the EMT masks due to extreme discomfort and their results were omitted from the study. Contrary to the original hypothesis, the EMT condition did not significantly decrease the amount of bench and squat repetitions completed to failure. It was confusing, however, that the blood lactate was found to be higher for the NM condition. It would be expected, since the mask’s purpose is to restrict the user’s access to oxygen, that the EMT group’s blood lactate would be higher since less oxygen would lead to more anaerobic respiration and therefore more lactate. The researchers attribute this phenomenon to less fast twitch fibers being recruited, which explains why the velocity for the bench and squat were lower for the EMT condition. They also admit that more studies need to be completed before that claim can be made.

Overall, this study was well controlled. All subjects diets were monitored carefully before all testing, and all results were obtained in a relatively consistent manner. However, using a 5-Point Likert scale opens the study up to subjective bias, especially since the subjects were not blinded to the different test conditions (they were consciously aware of wearing the mask). Also, the long-term aim of this study seems to be a little unclear. They mentioned in the introduction they wanted to see if the masks could serve as a RMT device, but only measured the acute responses. The effects of the EMT on respiratory muscle function would probably not be seen after weeks or even months after training. All in all, the study yielded few significant results to support that EMTs can acutely affect respiration at an anaerobic capacity.

Both studies were able to conclude that the EMTs did not completely mimic an environment of higher elevation. As mentioned previously, this probably has to do with the EMT’s inability to alter the partial pressure of oxygen. The first study had indicated that the mask served more as an RMT device, rather than a simulator of altitude. The second study, however, did not obtain results to support this claim. Elevation masks are a relatively new technology, and more extensive studies will need to take place before any conclusive claims can be made. Studies in the future, should probably follow the first’s with studying the effects long-term, rather than one time use. Additional studies lasting weeks or even months will be able to determine if EMTs have any long lasting effects on aerobic capacity and respiratory muscle function with training.

Questions to Consider

  1. How can Elevation Masks be designed differently to alter the partial pressure of oxygen?
  2. Do EMTs have any negative effects on the brain (oxygen deprivation, ect.)?
  3. What effects to EMTs have on the different portions of the respiration system (i.e. lungs, gas exchange, ect.)?


References/Further Reading

[1] Porcari, John P., et al. “Effect of Wearing the Elevation Training Mask on Aerobic Capacity, Lung Function, and Hematological Variables” Journal of Sports Medicine and Science, Online, 15(2): 379-386, 2016. 

[2] Jagim, AR, Dominy, TA, Camic, CL, Wright, G, Doberstein, S, Jones, MT, and Oliver, JM. “Acute effects of the elevation training mask on strength performance in recreational weightlifters”. Journal of Strength and Conditioning Research, Online, 32(2): 482-489, 2018.

[3] Elevation Training Mask

[4] Do Elevation Masks Work?

[5] Effects of Simulated Altitude on Maximal Oxygen Uptake and Inspiratory Fitness