Attention! Scientists have finally understood how and why muscle growth occurs. Rather do a new workout program and hurry to the gym. With a constant progression of loads, the transverse dimensions of the muscle fibers increase, which leads to an increase in their volume. This process is called hypertrophy. Now we will try to consider in detail the theory of muscle growth in bodybuilding.
Mechanisms of muscle tissue hypertrophy
When studying muscle tissue hypertrophy, scientists pay special attention to the role of satellite cells, growth factors, and the response of the immune system in this process. Let's consider each of these factors in more detail.
Satellite cells
Companion cells accelerate muscle growth, help repair tissue fiber damage, and support muscle cells. These cells got their name due to their location, namely, on the outer surface of the fibers. Most of the volume of satellite cells is occupied by the nucleus. They are dormant most of the time and can be activated when muscle tissue is damaged, say, after training.
After cell activation, satellites begin to multiply and are attracted to the fibers, merging with them. This leads to the restoration of damage. In this case, new fibers are not synthesized, but the size of the existing ones increases.
Satellite cells are active for two days after injury. The number of satellite cells depends on the type of fiber. Slow (type 1) in comparison with fast (type 2) have twice the number of satellite cells.
Immune system response
We have already said that during training, muscle tissue is damaged and the immune system reacts to this series of rather complex processes, the first of which is inflammation of the damaged areas. This is necessary to localize damage and clean these areas.
The immune system synthesizes various cells, whose task is to destroy metabolites of the process of fiber damage, after which they produce cytokines and growth factors. Cytokines are protein structures that "direct" the recovery process.
Growth factors
Growth factors are specific protein structures composed of proteins and hormones involved in the hypertrophy process. Let's take a look at three of the most interesting growth factors.
The first is IGF-1 (insulin-like growth factor), which is produced in muscle tissue. Its task is to regulate the production of insulin and accelerate the production of proteins. With a high concentration of this substance, muscle growth is significantly accelerated.
Fibroblast growth factor (FGF) is no less interesting. Today, scientists know nine forms of this growth factor that act on satellite cells. The more serious tissue damage is, the more actively FGF is synthesized. The last growth factor is the growth factor of hepatocytes. It is essentially a cytokine that performs a wide variety of tasks. For example, it is responsible for the migration of satellite cells to damaged areas.
Influence of hormones on the process of muscle hypertrophy
Hormones in the human body regulate all processes and the work of various organs. Moreover, their activity is influenced by a large number of factors, for example, nutrition, sleep, etc. Several hormones have the maximum effect on the process of muscle tissue hypertrophy.
Somatotropin
This hormone belongs to the peptide group and stimulates enzyme immunoassays in muscle tissues. It activates satellite cells, as well as the processes of their differentiation and proliferation. But when exogenous growth hormone is used, the effects it produces on muscles may be less related to an increase in the rate of contractile protein production and more to connective tissue accumulation and fluid retention.
Cortisol
Cortisol has a steroidal nature of origin and is able to penetrate from cell structures through membranes, bypassing receptors. It activates the gluconeogenesis reaction (the production of glucose from fatty acids and amines). In addition, cortisol can reduce glucose uptake by body tissues. Cortisol also triggers the breakdown of protein compounds into amines, which the body may need in a stressful situation. If we consider this hormone from the standpoint of hypertrophy, then it slows down the growth of muscle tissue.
Testosterone
Testosterone has a strong androgenic effect and affects the nervous system, muscles, bone marrow, skin, male genitals and hair. Once in muscle tissue, testosterone produces an anabolic effect, accelerating the production of protein compounds.
Types of muscle fibers
The power that a muscle can develop directly depends on the composition of the fibers and the size of the muscle. In total, two types of fibers are distinguished in muscle tissues: slow (type 1) and fast (type 2). They have a lot of differences, for example, in metabolism, rate of contractions, glycogen storage, etc.
Slow fibers - type 1
Fibers of this type are responsible for supporting the posture of the human body and bone structure. These fibers have the ability to work for a long period of time and they need less power of nervous excitation to start contractions. At the same time, they can develop less power than fast fibers. Through the use of preferential oxidative metabolism, type 1 fibers actively use carbohydrates and fatty acids for energy. An example of slow fibers is the soleus muscle, which is composed primarily of this cell type.
Fast fibers - type 2
These fibers make up muscles that are capable of developing great power over a short period of time. There is also a division of this type of fiber into two types - type 2a and type 2b.
Type 2a fibers are called glycolytic fibers, and they are a hybrid version of type 1 and type 2b. Fibers 2a have similar characteristics to the above types and use anaerobic reaction as well as oxidative metabolism to generate energy. If fibers 2a are not used for a long time, then they turn into type 2b.
Fibers 2b use only anaerobic reactions to generate energy and are capable of generating great strength. Under the influence of physical exertion, they can turn into type 2a.
Consider the muscle growth theories in this video:
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