Seluyanov V.N. Factors Stimulating Muscle Fiber Hypertrophy

Seluyanov V.N. Factors Stimulating Muscle Fiber Hypertrophy |
Empirical studies have shown [6] that with increasing external resistance, the maximum possible number of projectile rises or, as it is also called, repeated maximum (PM) decreases. External resistance, which in a motor action can be overcome at most once, is taken as an indicator of the maximum arbitrary strength (MPS) of a given muscle group in a given motor action. If the MPS is taken as 100%, then we can build a relationship between the relative value of the resistance and the repeated maximum.
The increase in strength is associated either with the improvement of muscle activity control processes, or with an increase in the number of myofibrils in muscle fibers [6,7,23].
An increase in the number of myofibillas simultaneously leads to an increase in the sarcoplasmic reticulum, and in general this leads to an increase in the density of myofibrils in muscle fibers, and then to an increase in the cross section [1,14,18,22]. A change in the cross section can also be associated with an increase in the mass of mitochondria [8.9], stocks of glycogen, and other organelles [14.15]. However, we note that in a trained person, in the cross section of muscle fiber, myofibrils and mitochondria occupy more than 90%, therefore, the main factor of hypertrophy is an increase in the number of myofibrils in muscle fibers, which means an increase in strength [14]. Thus, the goal of strength training is to increase the number of myofibrils in muscle fibers. This process occurs when accelerating the synthesis and at the same rate of protein breakdown. Recent studies have revealed four main factors that determine accelerated protein synthesis in the cell:
1) Stock of amino acids in the cell.

2) Increased concentration of anabolic hormones in the blood [3].
3) Increased concentration of free creatine in CF [4.24].
4) Increased concentration of hydrogen ions [10].
The second, third and fourth factors are directly related to the content of training exercises.

The mechanism of synthesis of organelles in a cell, in particular, myofibrils can be described as follows. During the exercise, ATP energy is spent on the formation of actin-myosin compounds, the performance of mechanical work. ATP resynthesis is due to creatine phosphate (CRF) reserves. The appearance of free creatine (Cr) activates the activity of all metabolic pathways associated with the formation of ATP, namely, glycolysis in the cytoplasm, aerobic oxidation in mitochondria - myofibrillar, located in the nucleolus and on the membranes of the sarcoplasmic reticulum (SPR). In fast muscle fibers (BMF), muscle lactate dehydrogenase (M-LDH) predominates, therefore, pyruvate, formed at the entrance of anaerobic glycolysis, is mainly transformed into lactate. During this process, hydrogen (H) ions accumulate in the cell. The glycolysis power is less than the power of ATP costs, therefore, Cp, N, lactate (La), ADP begin to accumulate in the cell.
Along with an important role in determining contractile properties in the regulation of energy metabolism, the accumulation of free creatine in the sarcoplasmic space serves as a powerful endogenous stimulus that stimulates protein synthesis in skeletal muscle. It is shown that there is a strict correspondence between the content of contractile proteins and the content of creatine. Free creatine apparently affects the synthesis of information ribonucleic acids (i-RNAs), i.e. for transcription in the nucleoli of muscle fibers (MV) [4.24].
It is assumed that an increase in the concentration of hydrogen ions causes labilization of the membranes (an increase in pore size in the membranes, this facilitates the penetration of hormones into the cell), activates the action of enzymes, and facilitates the access of hormones to hereditary information and DNA molecules [10]. In response to a simultaneous increase in the concentration of Cr and H, RNA is formed more intensively. The life span of i-RNA is short, a few seconds during a strength exercise plus five minutes in a rest pause. Then, the molecules of i-RNA bind to polyribosomes and provide the synthesis of cell organelles [1,3,5].
Theoretical analysis shows that when performing a strength exercise to failure, for example 10 squats with a barbell, at the rate of one squat for 3-5 s, the exercise lasts up to 50 s. In the muscles at this time, a cyclic process is going on: lowering and lifting with a barbell of 1-2 s is performed due to ATP reserves; after 2-3 seconds, when the muscles become less active (the load extends along the vertebral column and leg bones), ATP is being synthesized from the reserves of KrF, and KrF is being synthesized due to aerobic processes in the MMB and anaerobic glycolysis in the BMW. Due to the fact that the power of aerobic and glycolytic processes is much lower than the rate of ATP consumption, the reserves of KrF are gradually exhausted, the continuation of the exercise of a given power becomes impossible - a failure occurs. Simultaneously with the development of anaerobic glycolysis, lactic acid and hydrogen ions accumulate in the muscle (the validity of the statements can be seen from the data from studies on NMR installations [19,21]).
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