What is Muscle Protein Synthesis?

April 30, 2021 5 min read

What is Muscle Protein Synthesis?

There are actually two distinct types of protein synthesis - there is whole body protein synthesis, which affects the organs and then there is specifically muscle protein synthesis, which indicates the process of building muscle mass.  We will be focusing on muscle protein synthesis today as this is a fitness and health blog and also because this process is pivotal in exercise recovery and adaptation for strength. 

What is Muscle Protein Synthesis? 

As we are sure you’ve heard many times, protein is the building block of new muscle tissue.  When we consume protein, our body takes that protein and breaks it down into amino acids, which are absorbed in the gut and then transported throughout the body via blood circulation to be used by cells.  

A great analogy to help us understand this concept is thinking of muscle as a brick wall, and each brick to that wall is an amino acid.  Muscle protein synthesis is the process of adding bricks to the wall, but there is an opposing process as well known as muscle breakdown or degradation - which is the removal of amino acids from that muscle.  Both of these processes - protein synthesis and protein breakdown are constantly in motion, but the difference in speed that they occur is what gives us the result of more muscle mass, or less muscle mass.  

It is important to realize that muscle protein breakdown does not fluctuate very much based on our actions (i.e. exercise and/or food intake), so where our focus needs to lie is with optimizing muscle protein synthesis (SOURCE).   

What Type of Exercise is Optimal for Muscle Protein Synthesis? 

When it comes to resistance training versus cardio, it is relatively clear that weights and resistance are necessary for muscle development and growth.  Although within weight training, what methods seem to be the most effective for optimal muscle protein synthesis - or the growth of your muscles?  

There have been a number of studies that have tested different variations of sets, reps, and experienced vs. non-experienced lifters, and this is what we know so far: 

  • Different rep ranges are equally effective for muscle protein synthesis - As long as those rep ranges are taken close to failure.  For example, for a novice athlete, this may be more effective to do a set of 8-12 at a lighter weight, whereas an experienced lifter will find more effectiveness in a rep range of 1-8 reps (SOURCE). 
  • Working muscle groups more than once per week is ideal - Research has shown that muscle protein synthesis peaks around 24 hours, but lasts for a full 72 hours post-workout.  It is actually recommended to train muscle groups 2+ times per week for optimal protein synthesis and muscle development (SOURCE).
  • Larger rests between sets results in higher protein synthesis - When comparing a 1 minute rest to a 3 minute rest, the longer rest periods resulted in higher muscle mass development (SOURCE). 

The main takeaway is that for muscle development, we must exercise consistently, work our full body, and take adequate rest.  We cannot build muscle without movement, and for our body to adapt positively to run faster, lift more, and build strength - we must push it close to its limits on occasions.  

How Can Nutrition Optimize Muscle Protein Synthesis? 

Amount of Protein  

Obviously since protein is how our body receives amino acids, protein is essential for muscle protein synthesis, but how much do we need?  

There are actually quite a few different opinions on this topic, and non-active individuals vary greatly from athletes or those of us who train regularly.   The ‘recommended daily allowance’ (RDA) of protein is 1.0g per kilogram of body weight, but this is actually just to avoid malnourishment, this is not for optimal health or performance (SOURCE).  It is also important to note that this recommendation was created using an outdated testing model, and with the new testing model, the RDA gets closer to 1.2g per kilogram of body weight.  Again, this is for sedentary individuals to avoid malnourishment.  

So what about us athletes and training individuals?  

In the largest meta-analysis done around optimal protein intake for muscle recovery and building, the following ranges were found for optimizing protein synthesis (SOURCE): 

  • Female athletes required 1.4 to 1.7 grams per kilogram per day of protein.  
  • Male athletes required 1.7 to 2.7 grams per kilogram per day of protein. 

The best results were on the higher end of the range in this study, so we take the ‘average’ of these ranges at around 2.1 grams of protein per kilogram, which is nearly equivalent to 1g of protein per pound of body-weight (in US metrics).  

So for optimizing recovery and muscle mass development, it appears that between 0.9-1.2 grams of proteinper pound of body-weight is ideal for trained individuals. 

Whole Food Protein  

When comparing whole food protein sources, it is important to note that muscle protein synthesis depends on ALL 20 amino acids, which includes both non-essential amino acids that our body can create, and the 9 essential amino acids we must get from food.  Although the amino acid leucine is particularly important, as it has been shown to strongly activate anabolic (growth) signaling and muscle protein synthesis.  

It should be noted that plant-based proteins have limiting amino acids and lower amounts of leucine, and this can interfere with protein synthesis levels and effectiveness.  

Protein Powders  

The main thing that impacts protein synthesis positively is the timing and make-up of the protein source.  Casein protein is slower digesting compared to whey protein, which in turn results in whey protein sources providing a better muscle protein synthesis response.  This is why we developed our CLEAN Whey Protein with adequate amino acids, especially leucine, and made sure that it was easy to digest so you can get it quickly post-workout.  

Protein Timing 

Research shows that exercise improves the muscle protein synthesis response when it comes to protein ingestion.  This means that taking in your protein within 1-hour post exercise is ideal for maximal muscle mass development and recovery.  Protein supplementation also has other positive benefits including its ease of use, its ability to increase overall protein intake, and CLEAN’s delicious taste! 

Studies have also shown that the range per meal for protein intake seems to vary between 20-40g for optimal protein synthesis, and it is recommended to consume 4-5 meals or snacks throughout the day to assist best in muscle growth.  

Overall Calorie Intake 

The data is really clear when it comes to eating in a calorie deficit and the negative benefit it has on the rate of muscle protein synthesis.  Simply 3 days of a calorie deficit showed a reduction in muscle protein synthesis (SOURCE).  The most optimal place for intake to ensure high levels of muscle protein synthesis seems to be right around maintenance calories or slightly above.  

We know that was a lot of information, but the main take-aways to realize here are that for the body to be able to recover, maintain, and build muscle mass - it requires support to ensure muscle protein synthesis happens at a faster rate than muscle breakdown.  To provide this support, keep your workouts varied and challenging, and keep your protein intake up and consistent throughout the day, with adequate calorie intake overall!

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