What you need to know about muscle protein synthesis and breakdown

As the science of training and nutrition advances, terms that were once hidden away in scientific journals and only understood by specialists in given fields, are now making their way into the more mainstream areas of health and fitness. One of these terms is ‘muscle protein synthesis’ (MPS) and as the name suggests, this is the creation of new proteins within the muscle, which can lead to increased muscle mass. The body, including the muscles, is constantly ‘turning over’ protein through the breakdown and synthesis of proteins from amino acids.


It is this relationship between MPS and Muscle Protein Breakdown (MPB) that determines our Net Muscle Protein Balance (NMPB), simply put this means that...




We want to ensure our bodies are kept in a positive NMPB, where MPS outweighs MPB; otherwise, we are going to be losing muscle tissue. The impact of muscle loss is detrimental, not only for health, but can impact negatively on performance, recovery and a reduction in metabolic rate. It is therefore only in exceptional circumstances, such as changing from a strength sport to an endurance sport, that many people would intentionally want to lose muscle mass to have some form of performance or health benefit.


So what influences both muscle protein synthesis and muscle protein breakdown?

MPS can be triggered in three main ways. Firstly, it can triggered directly through mechanical stimulation, such as when we exercise, secondly through detection of amino acids, in particular, leucine, which is our nutritional MPS ‘switch’ and finally through anabolic (tissue building) hormones, such as testosterone (read about testosterone here)and growth hormone (read about growth hormone here).


One important thing to remember here is that although these may trigger MPS, we still need to actually provide the right amino acids and enough energy in the diet to help support muscle recovery and/or muscle growth. This is why a high protein diet, with fairly regular protein feedings of around every 4-6 hours, is often touted as being important to provide both leucine and a full spectrum of amino acids that are required for protein synthesis to take place and be sustained for those looking to maximise their muscle gains.


Beware, increasing protein intake beyond a certain point will have no major benefit in triggering MPS

One key thing to note here is that once stimulated MPS has a maximum ceiling; this is known as the ‘muscle-full’ effect. Increasing protein intake beyond a certain point will have no major benefit in terms of triggering MPS, but may have some benefits in reducing MPB and have other impacts on things like hunger. Bigger meals of protein will also typically take longer to digest and this has been suggested to provide a more prolonged stream of amino acids and a consistent positive nitrogen balance (nitrogen levels being an indicator of amino acid availability). This is one of the reasons why eating a larger protein meal before bedtime is suggested, especially using slower digesting proteins such as casein, in order to keep the body supplied with amino acids throughout the night. A great blend protein is the Pes Select Protein.


How can you maximise protein synthesis and reduce muscle loss?

To maximise protein synthesis our muscle full effect can be achieved with around 30g of protein obtained from whole food protein sources such as meat, dairy, eggs or through supplements such as whey protein. ‘Blend proteins’ are also potentially very useful as they also trigger MPS quickly, like whey protein, but also provide a prolonged supply of amino acids to give the benefits of casein.


MPB can be influenced in almost the exact opposite manner. Although exercise causes a breakdown in muscle tissue in order for it to be ‘remodelled’, not exercising can be much, much worse. This is known as the ‘use it or lose it’ principle and is an important reason why activity should be included alongside a high protein diet in order to protect muscle in populations that might be at risk of muscle loss, such as the elderly and those undertaking a weight loss program.


Loss of muscle during dieting can happen easily if due care and attention is not paid to these things, especially if under excessive calorie restriction as the body can adapt by reducing energy expenditure by eating into muscle, which is a key determinant of our metabolic rate… this is obviously something that we want to avoid. This attack on muscle is governed by hormones such as cortisol, often referred to as our stress hormone. Read more about the stress hormone here.


Chronic elevations of cortisol can be caused by stress of all sorts; from dietary stress, excessive exercise, poor lifestyle habits and work stress. As well as being catabolic in nature (increasing tissue breakdown), it also has a negative impact on hormones like testosterone, which as we mentioned earlier is an important hormonal regulator of MPS.


Whatever your goals maximise MPS

Therefore, whether our goal is to build muscle, or lose body fat, it is important to maximise our MPS and find strategies to help reduce excessive MPB. This can be achieved through proper nutritional and training strategies and by managing our stress levels by using appropriate recovery methods including enough quality sleep and ensuring, as far as is possible, that we develop methods to manage our day to day stress levels.


As always Team CSN are here to help, call or email us today and we can give you professional, unbiased advice on all your nutrition and supplement needs.