Muscle Reconditioning & The Role Of Branched Chain Amino Acids (BCAAs)

The ‘skeletal muscle adaptive response’ is a scientific term for ‘muscle growth’ or ‘muscle development’ as a consequence of exercise, particularly resistance training. When we exercise our bodies undergo muscle protein catabolism (breakdown), and to a larger extent muscle protein synthesis. When it comes to promoting muscle synthesis as well as staving off muscle catabolism, there are courses of action that can favourably support muscle anabolism (growth).

It is well established that whey protein supports muscle synthesis, especially if consumed within 30-60mins after training, but what is lesser known/understood is the role of BCAAs. The BCAAs include Leucine, Isoleucine and Valine and are known to be the main amino acids supporting muscle growth and development, as well as reducing muscle breakdown.

Why bother taking BCAAs & Whey Protein?

I’m asked this question on a regular basis, and I can understand why. We bang on about how amino acids are the building blocks of whey protein, and whey protein contains amino acids anyway, so the logical question is why bother taking both?

Well, the answer is this, Whey protein and BCAAs work the same, yet via subtly different mechanisms. They offer unique benefits, despite yielding the same outcome…muscle growth. BCAAs were originally thought to work by convincing the body not to break down so much muscle; it did this by drip feeding the muscle with amino acids enabling the muscle to draw upon this instead of eating itself. Alongside this, the BCAAs were seen to moderate hormonal responses i.e. stave off the accumulation of stress hormones such as cortisol, but it is now understood that BCAAs also help stimulate growth, and not just keep muscle breakdown (catabolism) at bay. The main amino acid for ‘stimulating’ growth, and I place this is inverted commas to emphasise the fact that it doesn’t enable actual tangible growth, but rather signals the body to start growing (even during the training session)…is Leucine.

Leucine : The growth stimulator

Leucine signals to the body that growth should take place, but on its own it lacks the building blocks to actually enable muscle anabolism (growth), so this is where the other BCAAs (Isoleucine and Valine) and whey protein come into play. In both animal and human studies, Leucine was seen to overcome the resistance of anabolic signalling pathways i.e. stopping the inhibitive signalling pathways that kick into action when training. So by ingesting Leucine before and during exercise your body is able to keep the anabolic pathways switched on, enabling your muscles to grow whilst training (Tipton and Luc van Loon, 2013)!


Tipton, K, D & Luc van Loon, (2013). Nutritional Coaching Strategy to Modulate Training Efficiency. Sodium Bicarbonate. Karger.

About the Author

Job Role Qualified Dietitian and Sports Nutritionist Qualifications BSc (Hons) Sports Science | BSc (Hons) Dietetics Tom has always participated in sport both recreationally and competitively which led to an unquenchable thirst for information on anything health, nutrition and fitness. After leaving school Tom went on to play for a football academy during which time he studied Sport and Exercise Science. From here he went on to study a BSc (Hons) Sport Science at UEA followed by his second BSc (Hons) degree, this time at the University of Hertfordshire studying Dietetics. Tom has worked in the fitness, educational and clinical nutrition industry starting out at David Lloyd Health and Leisure Clubs. He then went on to work as a Dietitian (RD) in the NHS, during which time he conducted clinics for healthy eating, weight loss and weight gain, as well as specialised consultations on Diabetes, IBS and Coeliac disease to name a few. He has vast amounts of experience at devising diet plans and supplement regimens, as well as working in the community with schools and competitive athletes. As Head Nutritionist and Supplement expert at Discount Supplements Tom is here to provide current and evidence based health and nutrition information to help you reach your health and fitness goals!
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