Protein 101
The macronutrient turned buzzword that’s being added on to anything and everything in the supermarket. Yes, you guessed it, protein. It is fundamental to many roles in our bodies. It helps to repair and build skeletal muscle and body tissue, permits metabolic reactions, regulates bodily functions and maintains optimal pH and fluid balance. Additionally, when there are insufficient calories from other nutrients or from fat stores within the body protein can undergo gluconeogenesis. Basically, the generation of glucose from non-carbohydrate substrates. For how important protein is for everyday bodily functions, how crucial is it for athletic performance…
For general populations there are nutritional recommendations with many counties setting their own values. In the UK, the recommended nutritional intake (RNI) for protein is 0.75g per kg of bodyweight per day (g/kg/day). Whereas in the US, the recommended dietary intake (RDI) for protein is 0.8g/kg/day. So, pretty much the same thing right?. To compare that to a relatable example, based on the UK’s RNI, the intake of a 75kg male would work out to be roughly 55g/day and roughly 45g/day for a 60kg female.
Before moving on to athlete recommendations it’s worth covering how those values were set. The current recommendations were put in place in the 1990s and were based on data captured from three populations in the 1970s. The data sets were collected utilising a method used for analysing protein intake called nitrogen balance. I don’t have to be in your head to know what you’re thinking. If the RNI is based on data and methods used in the 1970s surely it’s safe to say it’s a bit outdated?, and many experts would agree with you. Over the past five decades there have been many new methods that can be used to assess protein values that are far more reliable, one of which is called the Amino Acid Oxidation Method. Before you ask, yes I am one who believes the recommendations should be revisted, but, that is a story for another day…
Typically, athletes have higher metabolic demands and accumulate more muscle damage as a result of exercise, because of this and a myriad of other factors they should be consuming a higher amount of protein than the general public. For athletes two of the main governing bodies are the International Society of Sports Nutrition (ISSN) and the American College of Sports Medicine (ACSM). ACSM recommend a protein intake of 1.2-2.0g/kg/day, whereas ISSN recommend an intake of 1.4-2.0g/kg/day. Currently, endurance athletes would fall into the lower range with strength and power athletes targeting the upper range, however, recent studies are showing endurance athletes may benefit from the higher range as they spend significant time in a catabolic state which can lead to fatigue, excessive soreness, illness and injury. With this in mind, it might be worth endurance athletes opting for the higher range of the recommended protein intake to promote muscle maintenance and potential growth.
So, with protein being of importance to anabolic sports as well as catabolic inducing sports such as running. Let’s briefly touch on what influences said maintenance/growth, Muscle Protein Synthesis (MPS) .
Two of the main master regulators of cell metabolism and crucial to sporting performance are mTOR and AMPK. It would be a crime to attempt to squeeze these important metabolic pathways into a few lines of text so they will be covered in detail in another piece. For now, the main difference between them is that mTOR is active under nutrient rich conditions and associated with Muscle Protein Synthesis (MPS) whereas AMPK is active under nutrient poor conditions. Regardless of the sport, the aim of the game is to build or maintain muscle mass through MPS.
So, you now have an idea on protein intake per day but how much should you be aiming for around your exercise?
Pre-exercise, 0.3g/kg may reduce muscle catabolism, reduce soreness and increase MPS. However, this should be adjusted to individual gastrointestinal capabilities. If it causes more problems than solutions, it may be best to consume post-exercise only.
During, if permitted and possible, aim for 0.25g per kg of bodyweight per hour alongside a carbohydrate intake during high intensity or eccentric exercise to minimise potential muscle damage. By doing so, it can reduce creatine kinase levels from rising which can result in a reduction in feelings of muscle soreness.
Post-exercise, MPS is up regulated for 24 hours, an absolute peach of a window to kick start amino acid uptake and MPS or maintain muscle mass post endurance exercise
Aim for 0.25-0.3g per kg of bodyweight of quality protein 0-2 hours providing ~10g Essential amino acids. After that aim for doses 0.4g per kg of bodyweight, 3-5 hours apart for continued MPS in order to reach 1.6g/kg/day. If you’re dreaming and eating big then 0.55g/kg/day will set you up for the upper limit of 2.0g/kg/day. Not only will you be setting yourself up to promote MPS, if combined with carbohydrate it can increase muscle glycogen synthesis by 40-100% helping to replenish muscle and liver glycogen post-exercise.
Before I sign off, I want to quickly bring you back to MPS and mTOR. While it is important to consume complete protein sources or combining incomplete protein sources to ensure you’re getting a healthy porting of essential amino acids, one amino acid stands above the rest in relation to mTOR. Leucine is paramount for the activation of mTOR and, thus, MPS. The most recent research indicates leucine content between 700-3000mg is optimal for stimulating MPS. High leucine dietary sources include salmon, beef, chickpeas, eggs, soybeans and Brazil or cashew nuts. Prioritising salmon will also land the added benefit of omega-3 fatty acids, which are beneficial in reducing inflammation, with eggs being a potentially quick option while chickpeas are a great source for those following a plant-based diet. Nuts can obviously be used as part of a dish, but let’s be honest, they’re a great snack option.
