The Science of Growing your Muscles – Protein Synthesis and Training for Hypertrophy

Science of Growing your Muscles

Unlike fat loss, muscle growth can often be harder to achieve. This is largely because of the various principles of muscle growth that need to be implemented.

Not only is a calorie surplus necessary for the majority of people, you may also need to think about the timing of your protein intake as well as how you are training.

This article will tackle both of those topics, but it is also good to remember that progressive overload is necessary as well. 


Protein as a whole plays a really important role in muscle growth. Before considering the timing of protein, it’s first good to know how much you should be eating. While the reference nutrient intake is set at 0.75 grams of protein per kilogram of bodyweight, it is recommended that for muscle growth you consume 1.2 to 2.2 grams of protein per kilogram.

But Layne Norton has suggested that the amino acid leucine is responsible for the stimulatory effect of dirty protein on protein synthesis. There are twenty amino acids which form the building blocks of protein, but only nine of these are essential. 

In the late 1930s, William Rose discovered the essential nine amino’s after conducting a set of studies on rats. He gave them a controlled diet, containing fat, carbohydrates, vitamins, minerals and a source of protein that contained all 20 amino acids.

He then methodically removed single amino acids from the diet and observed what happened. The removal of some didn’t make a difference to the rats development and health, but the removal of others dramatically halted the rat’s development and eventually resulted in weight loss and death.

Rose repeated the experiment on people and discovered which amino acids are required in our diet. He found nine: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. 

But what has this got to do with timing your protein intake?

Protein synthesis is the process in which cells make proteins, and is often thought of as how our body ‘absorbs’ protein but our bodies don’t actually absorb protein (or amino acids). It’s really about what level of protein in a meal gives the maximum benefit of building muscle. 

In order to build muscle the body must increase the rate at which it synthesis muscle tissue above the baseline rate. Norton states that it appears maximising skeletal muscle protein synthesis requires approximately 15 grams of essential amino acids, and that 15 grams would contain 3.2 grams of leucine (which Norton suggested was responsible for the stimulatory effect on protein synthesis). 

This suggests that rather than thinking about how much protein you consume, you need to think about how much leucine you are consuming, which will differ from source to source.

A 2012 study suggested that 3 to 4 grams of leucine is needed to promote maximum protein synthesis. To achieve this you would need to consume around 133 grams of beef or 139 grams of chicken for example. 

Does it matter when you eat protein? 

It has been shown that the duration of protein synthesis in response to a complete meal containing protein, carbohydrates and fats is approximately three hours long. This suggests that it is unlikely eating another meal would be sufficient to induce another rise in protein synthesis. 

But, in terms of pre- and post-workout, it doesn’t make a huge difference. Most studies concluded that total protein intake is a far superior factor in promoting exercise-induced muscle development. 

So in short, it is best to consume 1.2 to 2.2 grams of protein per kilogram of bodyweight across the day in 25 to 50 gram increments, depending on the food source and how much protein you need to consume. It is also best to leave three hours between those meals/ snacks.


While nutrition is important, you do still need to consider your training. This is where training for muscular hypertrophy comes in.

Hypertrophy means the enlargement of an organ or tissue from the increase in size of its cells.  So muscular hypertrophy is the enlargement of the cells in muscle tissue. 

According to Schoenfield, there are three evidence based guidelines of hypertrophy training. These are sets, reps, and intensity. 

A 2017 meta analysis found that 10+ sets per muscle per week elicited greater hypertrophy than <10 sets. However, there was not enough research to see if high volumes would promote greater benefits. 

Schoenfield also found that periodising volume so that you push a lifter to the point of overreaching and then pulling back in the volume to allow proper recovery. For example, you might have 10 sets per muscle per week during the first month of a periodised cycle, go up to 15 sets the next month, and then culminate with a period of 20 sets of overreaching – then repeat. There are many ways that this can be incorporated into a program. 

When programming it’s important to also consider the way muscles are used in compound movements. For example, the biceps are involved in pulling movements for the upper body, like lat pulldowns, rows, etc. Therefore, they tend to need less isolation work. 

Schoenfield also found that hypertrophy can be attained across a wide spectrum of rep ranges, as high as 30 per set. However, there is also some emerging evidence that suggests a benefit to training with both high and low loads to maximise whole muscle hypertrophy, but this needs more research. 

Number of reps needed for hypertrophy can change depending on your specific training goals. Muscle strength is maximised when training heavy loads but muscular endurance is maximised with lighter load training. 

The typical range most people use for hypertrophy is between 8 and 15. However, many incorporate strength reps (3 – 8) in as well. 

As for intensity, there is conflicting evidence as to whether you need to be training till failure. Schoenfield believes that training till failure can be a great way to maximise hypertrophy in advanced lifters. 

It can be great for beginner and intermediate to use Eric Helms Reps in Reserve technique. This technique provides a way to gauge how many reps you stop short of failure. One good thing about this is that it can be a lot safer as well, especially if you are lifting by yourself. 

Reps in Reserve can also be a great way to achieve progressive overload as each week you can have less reps in reserve.