Leucine, isoleucine, and valine are three branched-chain amino acids (BCAAs) that are named “branched” due to their non-linear carbon atom structure. Amino acids are the building blocks of proteins, and proteins form the body’s structure. Amino acids are either produced in the body (non-essential amino acids) or must be obtained through diet (essential amino acids). BCAAs belong to the essential amino acid category that must be absorbed through diet. This article aims to discuss the benefits of BCAA consumption.
What are the benefits of BCAA consumption?
BCAAs are essential amino acids, meaning they are not produced in the body, yet they constitute one-third of the protein in human muscle tissue. Rich sources of BCAAs include dairy products, eggs, meat, chicken, and fish. BCAA supplements are widely available in the market and are commonly used in sports nutrition. BCAAs are unique substances because unlike most amino acids that are metabolized in the liver, these amino acids are metabolized in the muscle itself. Below are two important points about the function of these amino acids:
- Rapid absorption: BCAAs quickly enter the bloodstream and are easily absorbed by active tissues (mainly muscle) without being broken down by the liver.
- Provide more energy: BCAAs provide more energy for working muscles. The breakdown of BCAAs for energy production increases during prolonged exercise. BCAAs play an important role in protein metabolism by helping regulate the body’s recovery state (tissue building) or catabolic state (tissue breakdown).
How Do Branched-Chain Amino Acids Benefit Athletes?
These amino acids can provide numerous benefits for the body. Let’s examine these properties.
Delayed Fatigue During Extended Exercise
BCAAs delay both central and peripheral fatigue during exercise, enabling longer workout sessions. Peripheral fatigue (muscle tiredness) is delayed because BCAAs serve as an energy source during prolonged exercise. Even after the body depletes its glycogen reserves, muscles can utilize energy derived from BCAAs. Central fatigue (brain fatigue) can be delayed by BCAAs through preventing tryptophan absorption in the brain. Tryptophan is the primary form of the neurotransmitter serotonin, which causes central fatigue and produces feelings of weakness (muscle relaxation) and drowsiness.
Regular BCAA Use Improves Aerobic and Anaerobic Performance
Skilled cyclists who consumed 6 grams of BCAAs for one week participated in an exercise test measuring fatigue levels. Results showed:
- 4% increase in VO2max levels
- 13% increase in VO2 at lactate threshold (LT)
- 6% increase in power output at LT compared to the placebo group
In another study involving skilled cyclists, researchers found that 10 weeks of BCAA supplementation (12 grams daily) resulted in:
- 19% increase in peak power during sprint races
- 4% increase in average power relative to body mass compared to placebo
Most importantly, these results indicate that BCAA supplements can enhance both aerobic exercise capacity and anaerobic exercise performance.
BCAAs Strengthen the Immune System
Intense, high-volume training repeated over days and weeks can lead to fatigue and immune system suppression if athletes don’t rest sufficiently between training periods. Regular consumption of 12 grams of BCAAs has been shown to improve immune response during several weeks of intense endurance training in cyclists. How? Researchers found that BCAAs, serving as an energy source, can be utilized by immune cells in the gut, allowing the immune system to regenerate and protect itself against harmful pathogens. A strong immune system can aid recovery and reduce illness frequency.
BCAAs Protect Lean Muscle Mass (“Muscle Insurance”)
BCAAs have been shown to protect muscle mass under catabolic conditions associated with protein breakdown and muscle loss, such as in marathon runners and mountaineers ascending to high altitudes. During exercise, muscle protein breakdown, especially BCAA breakdown, increases for energy production. BCAA supplementation reduces the body’s consumption of amino acid (protein) reserves. Therefore, think of BCAAs as a policy for insuring your muscles.
BCAAs Enhance Muscle Protein Synthesis
This is likely why weightlifters love BCAAs. As mentioned earlier, leucine is the most important of the three amino acids in initiating muscle protein synthesis (MPS), essential for muscle building. A 2-3 gram dose of leucine (depending on body weight) is effective in stimulating muscle protein synthesis. For reference:
- A large egg contains 0.5 grams of leucine
- About 150 grams of red meat, chicken, or fish contains 2-3 grams of leucine
- Dairy products, especially milk protein, are rich in BCAAs
BCAAs Reduce Exercise-Induced Muscle Soreness and Damage
Taking BCAAs before and after exercise can reduce the intensity and duration of muscle soreness (the painful sensation that lasts several days after an intense or unusual workout). Additionally, studies have shown that BCAA consumption can reduce muscle damage in response to both endurance and resistance exercise. This means faster recovery and less muscle soreness between challenging periods.
