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Fri, March 19, 2021 | Fitness


The Phases of Muscular Hypertrophy (building muscle)

First, in our ‘resistance’ series we focused on the different aspects of Strength training. In part two we look at the in’s and out’s of muscular hypertrophy and what we can do from a training perspective to build muscle. 

What are our muscles made up of?

Muscle cells are referred to as myocytes. A myocyte is a long tubular shaped structure that has various different subcomponents. Its structure is organised in the following hierarchy:

Myocyte -> Myofibril -> Sarcomeres -> Actin & Myosin sliding protein filaments

Collectively, myocytes make up skeletal muscle tissue as a single functioning muscle group.

Muscular Hypertrophy 

Hypertrophy is an increase and the growth of muscle cells. Hypertrophy refers to an increase in muscular size achieved through exercise.

If you want to tone or improve muscle definition, lifting weights is the most common way to increase hypertrophy.

There are two types of muscular hypertrophy. ‘Functional’ and ‘Non-Functional’ although they will both yield an increase in muscle size they both have slightly different benefits. 

Functional (Myofibrillar) training will help with strength and speed. This is most common in track athletes, powerlifters, combat sports athletes and team sports (football, hockey, rugby). 

Myofibrillar hypertrophy is the increase in skeletal muscle protein mass through the creation of new contractile sarcomere units, a process known as sarcomerogenesis.

Skeletal muscles can adapt and respond according to the exercise-stimulus, by either becoming thicker in the cross-sectional area or increasing in functional length.

The capacity of force production of a myofibril is determined by the number of contractile actin and myosin sliding protein filaments. In other words… the more motor units you recruit, the more potential for the strength you have. 

Non-Functional (Sarcoplasmic) increases the storage our body has for glycogen (stored glucose) which can help give your body more sustained energy for endurance athletic events.

Sarcoplasmic hypertrophy is the increase in the volume of sarcoplasmic fluid. In other words, muscle cells become pumped-up with extracellular fluids and glycogen.

Therefore sarcoplasmic hypertrophy is said to increase lean muscle mass and perhaps even create an appearance of larger muscles. That said because this doesn’t involve an increase in the number of contractile protein structures, the capacity to generate force is not enhanced.

This means that having bigger shaped muscles doesn’t always equate to having more strength. 

Phases of Hypertrophy

To gain both functional and non-functional hypertrophy we can break things down into a further three phases. 

  1. Muscular Strength (functional)
  2. Muscular Damage (non functional) 
  3. Metabolic Stress (non functional)

Muscular Strength

Muscular Strength or ‘Mechanical tension is created by using a heavy load and performing exercises through a full range of motion for a period of time.

Typically the aim is to recruit the maximum number of motor units or even better go beyond your current capacity and recruit new motor units. We can do this with mental intent or speed and aggression of movement. 

When we do recruit new motor units by progressively overloading the weight lifted, we gain more potential for strength and an increased cross-sectional muscle mass.

We can also recruit a large number of motor units by doing maximal effort plyometric movements like a high box jump or max distance broad jump. 

Muscular Damage

Muscular Damage stimulates a repair response in the body. The damaged fibres in muscle proteins result in an increase in muscle size. 

The more time spent under load, the more tension provided. This would relate to the eccentric portion of the lift and contribute to cellular swelling (non-functional hypertrophy). 

Metabolic Stress

Metabolic stress occurs when the muscle fibres exhaust the available supply of energy. They aren’t able to continue fuelling muscular contractions or can no longer lift the weight properly, this can also lead to muscle gain. 

Both muscular damage and metabolic stress are important for achieving muscular hypertrophy. 

Within any phase, you don’t necessarily need to work your muscles to the point of “failure” — meaning you’re unable to follow through with repetition to get the results you want.


Incorporating both functional and non-functional hypertrophy in your training week or in distinct blocks where you focus on one at a time will contribute to muscular hypertrophy. 

Beginner trainees may favour a training plan that incorporates 1-2 functional hypertrophy and 1-2 non-functional hypertrophy sessions per week with adequate rest and recovery between sessions. 

More advanced trainees could look to spend consecutive weeks focusing on either functional or non-functional training before cycling onto the opposite for a change in stimulus. 

If you are interested in finding out more about how you could adapt and improve your current training program, reach out to one of our SF Coaches and be sure to sign up to find out more about the upcoming app launch

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