Muscle hypertrophy is an increase in the size of muscle fibers and therefore in muscle mass, observed when a muscle reaches a larger diameter or greater cross-sectional area. Through physical exercise, muscle work with overloads leads to an increase in muscle mass through this biological adaptation.
Muscle hypertrophy is an adaptation that our body implements in response to a stimulus given by an overload. It is an increase in the volume of the muscle due to the increase in volume of the elements that compose it.
The components within the muscle that contribute to increase its volume are: fibers, myofibres, ATP (Adenosine TriPhosphate), glycogen, phosphocreatine, connective tissue, capillaries and mitochondria.
We must also take into account the fact that, in each muscle, both fast (FT) and slow (ST) fibers coexist and that the two types of fibers should be trained differently.
This brief introduction should make us understand that there is no effective method for hypertrophy. But there are different methods of muscle stimulation, each of which will produce changes that overall will lead to hypertrophy.
What is muscle hypertrophy: definition and characteristics
The term hypertrophy refers to an increase in the volume of an organ or tissue, resulting from an increase in the volume of the cellular elements that make it up.
Hypertrophy is the increase in the volume of the cells that make up a tissue or organ. This modification does not alter the number of cells within the tissue or organ in question but increases their size. Generally hypertrophy is the result of a synthesis of greater quantities of structural proteins of the cell.
In medicine they define it as a biological and physiological adaptation which involves the increase in the volume of muscle fiber cells. In general, there is an increase in the cross-sectional diameter of the whole muscle due to two factors:
- Thickening of contractile proteins.
- Growth of the various constituent elements of the muscle such as capillaries, connective tissue, number and volume of mitochondria, glycogen, etc.
Difference between hyperplasia and hypertrophy
Although hyperplasia and hypertrophy are two distinct processes, they often occur together and can be triggered by the same mechanisms. What’s the difference?
Hyperplasia is an increase in the number of cells in an organ or tissue, which will therefore have a larger volume.
Hypertrophy refers to an increase in the size of the cells, and therefore of the organ, which will not have more cells, but bigger cells. The increase in size is not due to cell swelling, but to the synthesis of several structural components.
Types of muscle hypertrophy
There are two types of muscle hypertrophy:
However, there are some considerations to make: in physiology these two phenomena are distinguished to help us better understand the stimuli to look for during training, but in achieving certain sporting goals they can be connected to each other.
Muscle hypertrophy: what happens to the muscles?
Muscle hypertrophy occurs as a result of the application of increasing stimuli (stress) over time to the muscle through overload training, which can be represented by dumbbells, barbells, machines but also by bodyweight exercises.
Muscle tissue therefore adapts to the increased work demand (principle of progressive overload) by triggering a series of chemical reactions and processes aimed at maximizing protein synthesis.
In order for everything to be made possible, it is essential to follow a diet that is appropriate and functional to the goal. The anabolic processes of protein synthesis are made favorable under certain caloric conditions (surplus) and in the presence of adequate quantities of proteins and carbohydrates.
The growth of muscle mass can only occur through training stimuli, especially for athletes who want to work on strength. In order for the volume of muscle mass to increase during exercise, the muscles will always have to be subjected to slightly greater stress than usual.
But what exactly happens to your body?
If the muscle is overloaded with work, small lesions of the muscle fibers are produced, real microtraumas. However, all of this has a positive side. The human body is in fact an efficient and farsighted machine. During the post-training recovery phase, injured muscle fibers are repaired by storing new proteins, the raw material of muscles.
Muscle damage occurs when the smallest units of muscle cells (called sarcomeres) are damaged during exercise. Usually this injury occurs mainly in eccentric contractions and is a real muscle injury (reversible) that leads to muscle pain (DOMS).
Muscle damage also activates the immune response. Our body therefore sets in motion a non-specific immune defense to eliminate the damaged elements. It seems that the activation of some immune cells is responsible for the increase in muscle fibers.
In addition, muscle damage stimulates the activation of satellite cells (deactivated and silent muscle cells) which aid in the regeneration of damaged muscle tissue to prevent the damage from leading to cell death.
Our body not only repairs the damage to the muscle structures, but also further strengthens the fibers to prepare the muscles for new efforts of the same type. The entire system thus adapts to the training stimulus and muscle growth takes place.
Metabolic stress is sometimes used to facilitate muscle hypertrophy. Metabolic stress occurs when we increase workloads on a muscle or a certain group of muscles. This causes a progressive increase in muscle growth.
In particular, metabolic stress refers to the accumulation of metabolites in the muscle fibers such as lactate, hydrogen ions and inorganic phosphates and is characteristic of workouts with:
- A moderate and/or high number of repetitions.
- Very short recovery times.
- Restriction of blood flow.
- Maintaining constant voltage.
Other elements that are able to amplify the effects can also be included, such as the strong production of myokines and free radicals or cell swelling.
All the benefits of muscle hypertrophy
The benefits of training aimed at increasing muscle mass are diverse. Although what most frequently pushes a subject to model his own muscles is the aesthetic reason, it is not uncommon for this to involve, often indirectly, an improvement in the person’s self-esteem with positive repercussions on the psychological sphere.
However, even before the aesthetic purpose, the increase in muscle tissue is useful for the subject’s ability to express strength. Of the various strength determinants, the most impactful as a percentage is the size of the cross-sectional area.
The strengthening of deficient muscle groups guarantees, in part, the improvement in sports such as calisthenics, powerlifting and any other sport that requires strength and power.
From a purely health and preventive point of view, the impact on:
- Global efficiency of the organism.
- Improvement of body composition, ally against overweight and obesity and for weight loss.
- Less predisposition to dysmetabolic pathologies.
- Better management and uptake of nutrients (insulin sensitivity).
- Release of a series of beneficial chemical mediators.
- In the field of rehabilitation and the physiological physical decay given by advancing age (sarcopenia) it becomes essential to seek an increase/maintenance of an optimal muscular trophism and consequently of functional autonomy.
Through hypertrophy training your body learns to engage more muscle fibers than it usually does. Furthermore, in this way the so-called intramuscular coordination is improved, i.e. the ability of the individual fibers to collaborate with each other.
For example, as you perform more and more push-ups and level up your workout, you will simultaneously activate more and more parts of your biceps and triceps.
If you are interested in the topic, discover our in-depth study on arm training.
Muscle hypertrophy and training: how to stimulate it