Phil Learney is a performance coach specialising in strength, conditioning and nutrition. He is based in London.
In theory, adding lean muscle mass is easy. All you need to do is synthesise more protein than you break down. If you do, you are in an anabolic state, but if degradation outstrips synthesis, then you are in a catabolic state. That’s why a positive protein turnover is critical to your success in attempting to increase the size and strength of your skeletal muscles. Think about it: if you can build more muscle tissue through your diet than you damage through training, you are going to get bigger.
In reality, the ratio at which protein synthesis and degradation occurs is determined by your age, gender, hormonal profile, nutritional profile and training regime. However, you can take steps to limit protein degradation while enhancing utilisation.
All intracellular – and many extracellular – proteins are in a constant state of turnover. The degradation of proteins into smaller, more useable, polypeptides or amino acids is called proteolysis. It occurs by the separation of the peptide bond through hydrolysis, the process where bonds are broken apart with the addition of a water molecule, and is facilitated by cellular enzymes called proteases.
This process is continuous, yet highly selective, for a multitude of reasons, including the preservation of the integrity of certain protein-based structures, such as hormones.
Unfortunately, preventing the constant breakdown of protein and keeping synthesis as elevated as possible isn’t as simple as shoveling as much protein down your throat as possible.
There are a significant number of negative adaptations that occur from this approach, including an adverse effect on glycogen-mediated pathways, which are the intracellular pathways that signal for the generation of glucose from carbs. Therefore, the starting point should be the best way to minimise degradation, then examining ways to increase synthesis.
The need for protein
For the general population the recommended daily intake of protein for men is 55g in the UK, and 56g in the US. That American guys need one extra gram of protein each and every day compared to us Brits demonstrates that this RDA shouldn’t be taken too seriously. Another widely-accepted figure is 0.8g per kilo of bodyweight per day, yet this figure is also flawed.
It’s based largely on the hypothesis that tissue maintenance revolves around nitrogen balance within the body, but the methodology utilised in measuring nitrogen balance isn’t a tissue-specific metric, so therefore cannot be seen as an accurate measure when evaluating tissue loss or gain.
For athletic populations the scientific literature suggests that for positive muscular adaptations daily protein intake needs to be at least 1.5-1.6g per kilo. If we take this as the absolute minimum requirement for preserving lean body mass, then we can begin to consider increasing this number, by evaluating other important factors, to ensure a positive balance of synthesis over breakdown.
The level of free androgens, particularly testosterone, increase muscle protein synthesis, according to numerous studies. This indicates that someone with a genetically higher androgen profile would require a higher basal amount of dietary protein. This would also be applicable for drug-assisted athletes.
Also, if you are dieting and restricting caloric intake, we know that over time the level of total and free testosterone will drop alongside thyroid hormones and plasma levels of insulin and IGF-1.
This has the twofold effect of lowering protein-sparing hormones whilst elevating the use of protein as a fuel. Therefore, this would suggest that protein requirements should increase linearly as caloric intake decreases.
If you lower the carbs in your diet then the oxidation of protein is stimulated as you move between glycogen-mediated pathways (the generation of glucose from carbs) and gluconeogenesis (the generation of glucose from non-carb sources). If your rationale for lowering of calories is to also reduce subcutaneous fat stores, then less preferential fat also becomes fuel. The leaner someone becomes the more evident this is. Again, an increase in protein intake would be recommended.
Finally, another major consideration is that the higher your volume of training the greater the protein requirements. During phases of training that utilise higher volumes – or all the time for experienced bodybuilders – the net amount of protein required will increase.
After careful consideration of the above factors, and also the caloric intake of the individual, we can come to a strategy pertaining to protein intake and maximising synthesis. Research currently supports around 2-2.4g per kilo when factoring in the above scenarios. To claim that this is an absolute would be nonsensical because there are too many variables to consider, but it certainly puts us in a position where protein degradation is prevented at the very least. In my view there currently isn’t enough research to support specific maximal protein dosing.
Another major factor when investigating maximal protein synthesis is the leucine content of the proteins we consume. Leucine, an essential amino acid, has a major influence on protein synthesis and the ability of dietary proteins to be utilised in tissue regeneration. Leucine intake at 0.05g per kilo has been show to saturate the mTOR pathway – the intracellular signalling pathway that contributes to hypertrophy – and thereby increase maximal protein synthesis.
Target versus timing
A final consideration for maximal protein synthesis is that the overall target of daily protein appears to more important than both frequency and timing. The bodybuilding standard of six-to-eight feedings per day in my view only appears to be beneficial when it aligns with daily total protein intake.
Therefore, to ensure that you maximise protein synthesis and minimise protein breakdown, the first step should be to evaluate your baseline dietary protein requirements, based on the factors above, so that degradation is prevented from occurring. This will maintain your current level of muscle mass.
From this point, you need to consider your dietary and training protocols to further adjust your protein intake accordingly, ensuring adequate leucine, to stack the odds of synthesis – and consequently lean muscle growth – in your favour.