Turn GROWTH MODE On With Leucine : mTOR Is Key To Growth : Leucine Is Key To mTOR...Simple!

Amino acids have a major part to play in physiological development, particularly when it comes to muscle size and body composition. Legend has it that the Olympic Wrestler Milo of Crotona first demonstrated the importance of resistance work and consuming amino- acids for growth through his progressive overload training whereby he would squat with a calf on his shoulders right up until the day it became a bull, after which he would finally carry the bull into the Olympic stadium, squat with it and then eat it! Albeit this is a myth from over 2500 years ago, but the sentiment remains the same…we need to exercise, recover and replenish in the form of protein and amino- acids in order to promote muscle growth.

Role of amino acids and mTOR

If you haven’t heard of mTOR before then you will hopefully see how important it is to your progression in terms of muscular development, tone and definition. The mammalian target of rapamycin (mTOR) helps to stimulate muscle growth, whilst the amino acids we consume on a daily basis (via food or supplements) help to activate it. So what is the relevance of mTOR? Well, it is thought that we can predict how much muscle a person is likely to add by how well their bodies can activate the protein mTOR (Baar and Esser, 1999).

What is mTOR?

The mammalian target of rapamycin (mTOR) is an enzyme known as a kinase, this kinase basically adds negatively charged phosphate groups onto other proteins. The importance of this negative charge means that the target proteins (proteins receiving a message from the brain) change their shape which can result in one of a number of things. The mTOR enzyme can change the activity of the target protein (basically make it do something else), change the location of the target protein, or change the ‘binding partner’ of the target protein. So what’s the relevance of all this? Well, in the case of mTOR, the ‘target proteins’ that I spoke of are key to controlling muscle protein synthesis. So considering muscle protein size and strength is directly linked to your bodies ability to synthesise (grow) and degrade (breakdown) muscle protein, it makes absolute sense to maximise mTOR!

Turn mTOR on to grow!

Scientists are clear on the role of mTOR and  promoting muscle protein synthesis (growth). mTOR’s role in prompting muscle growth after resistance exercise is well understood and evidence based, and this was further validated when people were given an mTOR inhibiting drug which seemed to negate (reduce) muscle synthesis after training. So the need to turn mTOR on after exercise is paramount…but how do you do it?

How to turn mTOR on!

By activating mTOR you are literally turning BEAST MODE on, and one of the main ways that you do this is through amino acid feeding. All amino acids are needed in order to effectively turn mTOR on, but one Branched Chain Amino Acid (BCAA) activates mTOR better than any other…LEUCINE! So if you want to maximise your training capacity and growth then consider a BCAA supplement that delivers a Leucine, Isoleucine and Valine ratio of approximately 2:1:1 or 4:1:1, and take it before and during your training session.


Baar, K. (2013). Using molecular biology to improve the effects of amino acids. University of California Davis. Nestle Nutrition Institute.

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!
Post a Comment

Please wait...