What Causes Muscle Growth?

There are a few factors that are necessary for body muscles to grow. Research shows that for body muscle to grow, one has to subject the body to physical stress in the form of workouts. Working out leads to increased hormone release and an increase in the flow of vital nutrients to body muscles. One also needs rest, whereby muscle repair and growth occurs. In this article, we will delve into what causes muscle growth.


Your muscles need some form of stimulus for them to grow. For most people, such stimulus comes from exercise. Exercising forces your muscles to work. In the process of working, they use energy and cause microscopic damage of fibers.

The growth of muscles occurs by two factors; hypertrophy and hyperplasia. Hypertrophy is muscle growth caused by an increase in the size of muscle fibers, while hyperplasia is muscle growth due to an increase in the number of muscle fibers.

Hypertrophy can occur due to an increase in the size of the contractile or non-contractile portions of the muscle. The former is known as sarcomere hypertrophy while the latter is sarcoplasmic hypertrophy. Sarcomere hypertrophy leads to a small increase in muscle diameter and a significant increase in muscle density. Sarcoplasmic hypertrophy involves a substantial increase in the diameter of the muscle and a decrease in muscle density. The extent to which each of the two forms of hypertrophy occurs depends on how you train.

Lifting weights breaks down body muscles. The body reacts to this by growing its muscles in order to be ready for such intense workout in future.

Training volume determines how fast your muscles grow. More intense training will most probably lead to more rapid muscle growth. During or after a workout, the body releases hormones such as growth hormone, insulin, insulin-like growth factor, testosterone, and cortisol. Cortisol breaks down carbohydrates to supply the body with energy. Growth hormone controls the release of the insulin-like growth factor, which is an anabolic hormone. Testosterone causes the nervous system to signal the muscle to rebuild. For muscle growth rate to be sustained, one needs to attain higher levels of training intensity.


After muscles have been put to work, they require nutrients to replenish their power. The most important nutrients for this process is proteins. For muscles to grow, nutritionists recommend one to two grams of protein per kilogram of body weight. Not only does protein lead to muscle growth, but it also does muscle repair and is essential in hormone production. Liquid protein is the most recommended because it is easier to digest and absorb compared to solid protein. Generally, better nutrition leads to faster muscle growth.


During resting, the muscles repair the microscopic damage and grow. Ingested Carbs and creatine replenish glycogen and phosphocreatine in the body, while amino acids from food trigger protein synthesis. It is protein synthesis that is responsible for the repair of damaged muscle and the growth of muscle fibers. Resting is, therefore, an essential aspect of muscle growth.