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What are BCAAs?

Proteins are made from 20 amino acids, some of which the body can make itself (non-essential) and some of which must be consumed in the diet (essential). Branched chain amino acids (or BCAAs) are three essential amino acids- leucine, isoleucine and valine. Together, they make up 35% of the essential amino acids contained in muscles(1). These must be consumed in the diet, because body cannot make them out of other amino acids. BCAAs are naturally found in foods that are high in protein, with the highest concentrations found in animal protein, including meat and dairy foods.

Benefits of BCAAs

It is suggested that the effects of branches chain amino acid supplementation is especially beneficial in sport. Here are some of their benefits:

Increase muscle growth

The branched chain amino acid, leucine, is responsible for making muscle, by activating a pathway that stimulates muscle protein synthesis.

Reduce DOMS

Delayed onset muscle soreness (DOMS) is thought to be caused by tiny tears in the muscle caused by exercise. Studies have shown BCAAs are able to reduce protein breakdown during exercise, and therefore reduce the length and severity of DOMS.

Prevent muscle breakdown

Muscle degradation occurs when protein breakdown exceeds muscle protein synthesis. Because BCAAs account for 35% of the essential amino acids found in muscle proteins, it’s important that the BCAAs and other essential amino acids are replaced during times of muscle wasting to halt it or to slow its progression.


When to take BCAAs?

The best time to consume BCAAs is prior to or during exercise. During exercise, muscle protein breakdown is increased, and protein synthesis is reduced, thus inducing a negative muscle protein balance. It is suggested that BCAAs can prevent muscle tissue breakdown and increase protein synthesis if taken before or during exercise. BCAAs can also be consumed immediately after exercise to stimulate muscle protein synthesis and build muscle.


BCAAs for endurance sports

Prolonged exercise and intense endurance sports increase muscle protein breakdown as it uses our muscle BCAA pool to help energy production. Therefore, it is useful to ingest BCAAs before, during and after in order to prevent muscle breakdown and increase protein synthesis during the recovery period. BCAA supplementation may also facilitate adaptations in aerobic power and post-exercise recovery in trained endurance athletes.


Sources of BCAAs

BCAA Perform

BCAA Perform contains 6g of branched chain amino acids known as BCAA’s ( 3 g leucine, 1.5 g isoleucine and 1.5 g valine) in a 2:1:1 ratio. The product also includes 5g of L-glutamine and 1.5g of L-Arginine. This is taken in a powder form and is best mixed in an SiS Protein Shaker with other SiS products.

BCAA Capsules

BCAA capsules provide 4g of Branched Chain Amino Acids in a 2:1:1 ratio of Leucine, Isoleucine and Valine. Packed into a convenient capsule format rather than a BCAA powder, these can be taken pre, during or post workout or anytime throughout the day.

SiS Advanced Isolate+ 

SiS Advanced Isolate+ contains 9g of BCAAs, including 5g of leucine. This is the ideal shake to have before or after exercise.


WHEY20 also provides 7g of BCAAs, without the need for water and shakers. Use before, during and/or post work-out or throughout the day to get your 20-25g of protein every 3-4 hours(6).




Should I take BCAAs if I am a vegetarian?

Yes. If you are a vegetarian, you may struggle to get enough BCAAs within your normal diet. Although soy protein does contain essential amino acids, the BCAA levels are lower than in sources such as whey protein. Therefore, vegetarian or vegan athletes may benefit from consuming BCAAs before, during and/or after exercise.

What are ‘free form’ BCAAs?

Free form amino acids are already in a pre-digested form, ready to be used by your body. They can be rapidly absorbed into the blood stream and can be taken up by muscles during exercise.

Why should I use BCAAs after strength or resistance training?

The aim of resistance or strength training is to make the muscle stronger by altering its structure and increase muscle mass. Given that the BCAAs are especially important in stimulating muscle protein synthesis, it is useful to also consume BCAAs before, during and/or after strength training sessions.

Should I take BCAAs when doing low carbohydrate training?

Yes. Fasted training has become a popular way to manage your body composition and promote aerobic adaptations in muscle. However, with depleted glycogen stores your body is more prone to using BCAAs as the energy source, leading to muscle breakdown. Consuming BCAAs before and/or during low carbohydrate training may help prevent muscle loss. This allows the athlete reap the benefits of fasted training.

Are there any side effects?

There are no reported side effects of amino acid supplementation, but do not exceed the recommended dose.


Take home messages

  1. Free form BCAA’s are absorbed rapidly into the blood-stream, meaning they can be delivered to our muscles quickly.
  2. Supplementing with BCAAs before, during and/or after a work-out may help reduce muscle breakdown and muscle soreness.
  3. Strength training: BCAAs are commonly used to stimulate muscle protein synthesis in the post-exercise recovery period. Leucine provides the “trigger” to switch on this process.
  4. Endurance training: BCAAs are used to contribute to energy production during exercise, especially when doing low carbohydrate training.



  1. Kephart, W. C., Wachs, T. D., Mac Thompson, R., Mobley, C. B., Fox, C. D., McDonald, J. R., & Pascoe, D. D. (2016). Ten weeks of branched-chain amino acid supplementation improves select performance and immunological variables in trained cyclists. Amino Acids48(3), 779-789.
  2. Pasiakos, S. M., McClung, H. L., McClung, J. P., Margolis, L. M., Andersen, N. E., Cloutier, G. J., & Young, A. J. (2011). Leucine-enriched essential amino acid supplementation during moderate steady state exercise enhances postexercise muscle protein synthesis. The American Journal of Clinical Nutrition94(3), 809-818.
  3. MacLean, D. A., Graham, T. E., & Saltin, B. (1994). Branched-chain amino acids augment ammonia metabolism while attenuating protein breakdown during exercise. American Journal of Physiology-Endocrinology And Metabolism, 267(6), 1010-1022.
  4. Wagenmakers, A. J., Beckers, E. J., Brouns, F. R. E. D., Kuipers, H. A. R. M., Soeters, P. B., Van Der Vusse, G. J., & Saris, W. H. (1991). Carbohydrate supplementation, glycogen depletion, and amino acid metabolism during exercise. American Journal of Physiology-Endocrinology and Metabolism260(6), 883-890.
  5. Impey, S. G., Smith, D., Robinson, A. L., Owens, D. J., Bartlett, J. D., Smith, K., & Morton, J. P. (2015). Leucine-enriched protein feeding does not impair exercise-induced free fatty acid availability and lipid oxidation: beneficial implications for training in carbohydrate-restricted states. Amino Acids47(2), 407-416.
  6. Witard, O. C., Jackman, S. R., Breen, L., Smith, K., Selby, A., & Tipton, K. D. (2014). Myofibrillar muscle protein synthesis rates subsequent to a meal in response to increasing doses of whey protein at rest and after resistance exercise. The American Journal of Clinical Nutrition, 99(1), 86-95.
  7. Churchward-Venne, T. A., Breen, L., Di Donato, D. M., Hector, A. J., Mitchell, C. J., Moore, D. R., … & Phillips, S. M. (2014). Leucine supplementation of a low-protein mixed macronutrient beverage enhances myofibrillar protein synthesis in young men: a double-blind, randomized trial. The American Journal of Clinical Nutrition99(2), 276-286.
  8. Churchward‐Venne, T. A., Burd, N. A., Mitchell, C. J., West, D. W., Philp, A., Marcotte, G. R., … & Phillips, S. M. (2012). Supplementation of a suboptimal protein dose with leucine or essential amino acids: effects on myofibrillar protein synthesis at rest and following resistance exercise in men. The Journal of Physiology590(11), 2751-2765.
  9. Jafari, H., Ross, J. B., & Emhoff, C. A. W. (2016). Effects of Branched-Chain Amino Acid Supplementation on Exercise Performance and Recovery in Highly Endurance-Trained Athletes. The FASEB Journal30(1), 683
Written By

Ted Munson (Performance Nutritionist)

Ted is a Performance Nutritionist here at Science in Sport.