Hypertrophy – Increase of muscle size fibres. It’s an anabolic process of building up of muscle tissues. It occurs when protein synthesis exceeds the protein breakdown.



Protein Synthesis is the creation of new protein within the body. This is aided by the food we eat. When we consume protein sources, these are broken down and amino acids are built up and chained together to make new proteins. Not all proteins in the body are muscle tissue. It depends on the amino acids and the order they are chained together based on a specific type of protein in your body.



When protein synthesis exceeds the protein breakdown that is when we create Net Anabolic State which is concussive with Muscle Hypertrophy or growth.



Muscle fibre can increase in size. When we think about increasing muscle fibres in length, then we think about increasing Sarcomeres in series. But we want to focus on the process of increasing Sarcomeres in parallel. This is the response from resistance training.



Within the muscle fiber, we have Myofibril. We can think of it as a rod or unit where muscle contraction takes place. When running the length of the muscle fibre we have the sarcomere. It’s the specific unit in muscle fibre where muscle contraction occurs. It’s called the Sliding Filament Theory.



Muscles contain bundles of Muscle Fibers and these Muscle Fibers contain Myofibril which contains Sarcomeres. Myofibril and Sarcomeres are microscopic parts of the muscles where we look at how muscle growth occurs.



Hypertrophy, caused by the resistance training happens when there is an increase in the size of Myofibrils and Sarcomeres in parallel. And you can think of it as stacking them next to each other.



We can think of Hypertrophy in 2 categories. Contractile Hypertrophy and Non-Contractile Hypertrophy.

Non-Contractile Hypertrophy is also called Sarcoplasmic Hypertrophy which is increasing the muscle cell by non-contractile components such as glycogen and hydration. Non-Contractile Hypertrophy is also known as Non-Functional Hypertrophy. However, the term “Non-Functional” is debated. There are arguments that suggest that these non-contractile components do contribute towards Muscle Hypertrophy.



The Contractile Hypertrophy is what you focus on with resistance training. That’s an increase in Myofibers and Sacromeres in parallel to each other.



You can think of muscle fibre growth as a response to a stimulus. The adaptation to the stimulus. Your weight training is forcing adaptations within the microscopic level of muscle fibres and acting upon sarcomeres and muscle fibres which is, therefore, going to create a bigger muscle.



Muscle growth categories are:

Mechanical Tension

Metabolic Stress

Muscle Damage



Mechanical Tension is created by force generation and also the stretch of the muscle. When we are lifting weights or doing callisthenics or any type of challenging resistance training the concentric contraction will require force generation as will be eccentric. However, the eccentric contraction is known as passive tension, stretching of the muscle. Eccentric contraction is related to specific Type 2 muscle fibres.



The tension associated with resistance training disturbs the integrity of skeletal muscle. The response, your rest and your protein intake is important for protein synthesis, creation of the protein and rebuilding of the muscle tissue.



Muscle Damage is caused by micro-tears in muscle fibres. It could be smaller or larger tears but these localized tears contribute to muscle growth.



Metabolic Stress is an accumulation of metabolites such as lactate, which does not cause muscle soreness. These metabolites can be thought of having an indirect impact on hypertrophy. Accumulation of metabolites by consistent resistance training can create an environment which helps to elicit a hypertrophic response, such as creating an acidic environment which can lead to degradation of muscle fibres.