Types of muscle fibers

Muscles promote breathing, blood and lymph flow, improvement of metabolism, conversion of chemical energy occurring in muscle tissue into heat and mechanical energy. The composition of muscles includes water (80%) and solid substances: AEF, proteins, glycogen, creatinine, phosphates, lactic acid, amino acids, salts of organic and inorganic acids. Skeletal muscles are composed mainly of "white" and "red" muscle fibers, there are also "pink" muscle fibers.

Red muscle fibers, which contain a large amount of myoglobin, contract slowly (90-140 msec), restore AEF reserves slowly, and have high endurance.

White muscle fibers, which contain a small amount of myoglobin, contract quickly (within 40-90 msec), quickly restore AEF reserves, but tire quickly due to the rapid accumulation of lactic acid. They are endowed with great power and aerodynamic capabilities. Those muscle cells contain the explosive power in weightlifting, boxing, sprinting... .

Pink muscle fibers, which are considered an intermediate type in all their properties, can acquire the properties of fast or slow-twitch muscle fibers, depending on the nature of training. therefore, thanks to special training, it is possible to change the ratio of red and white muscle fibers. In general, white muscle fibers are 20% more than red ones. As a result of physical work, overgrowth of muscles occurs due to the thickening of muscle fibers. in case of significant thickening, longitudinal splitting of muscle fibers is possible with the formation of several "Daughter" muscle fibers, which have one common tendon.

There are 2 types of muscle hypertrophy Sarcoplasmic (from the Greek sarkos - flesh or cytoplasmic) and Myofibrillar (muscle).

In case of Sarcoplasmic hypertrophy, muscle fibers are thickened due to the sarcoplasm of their non-contractile part. This type of hypertrophy develops in slow-twitch muscle fibers and contributes to increased muscle endurance without significant changes in muscle strength.

In the case of Myofibrillar overgrowth, muscle fiber thickening occurs at the expense of their contractile part, muscle fiber thickening and increasing the density of their arrangement. This type of hypertrophy develops in fast-twitch muscle fibers and contributes to a significant increase in muscle strength. muscle strength also depends on male sex hormones. Myofibrillar overgrowth develops during static, and sarcoplasmic overgrowth during dynamic exercises.