Dmitry Rassokhin – Energetics of muscular activity
The direct energy source for muscle contraction is the reaction of enzymatic hydrolysis (hydrolysis – the cleavage of chemical bonds in a molecule of a substance with water) molecules of adenosine triphosphate (ATP).
Cleavage reaction adenosine triphosphate is accompanied by the release of a significant amount of energy used during muscle activity. ATP is the universal energy source for all biological processes in a living organism
(in all cells and cellular structures of living organisms). Adenosine triphosphate (ATP) refers to high-energy compounds that differ by the presence of chemical bonds, which accumulated a large amount of free energy.
The enzymatic reaction of ATP hydrolysis is irreversible.
If the contraction of muscle fibers requires an energy of ATP, it is possible to reverse the process associated with subsequent stretching (relaxation) of the muscle fibers, the energy of ATP is not required.
Conversion of chemical energy into mechanical energy that occurs in muscle fibers, according to its principle is different from the action of heat, as if the chemical energy first would be turned into heat and then into mechanical work, while the conversion of chemical energy released through the oxidation of organic substances) into heat, the inevitable temperature increase inside muscle fibers would lead to denaturation of contractile filaments.
Denaturation – the process of destruction of the spatial structure of protein molecules under the influence of various negative factors (one of which is a high temperature).
Under natural conditions the level of ATP content in muscle is relatively constant, and does not change under the influence of sports training.
Increasing the ATP concentration above the permitted level leads to loss of ability of muscle fibers to contraction; in turn, the reduction of ATP levels leads to a functional abnormality of the process of relaxation in muscle fibers. The movement of molecules of ATP in the muscle fiber occurs in the process of simple diffusion, thus can be regulated by the relative balance of ATP inside the muscle fibers.
The reserves of ATP in muscle fiber insignificant and can provide only one – two single contraction. During prolonged muscle activity of lower concentrations of ATP in the muscles does not occur, since simultaneously with the expenditure of ATP are processes of recovery (resynthesis) of ATP. The speed with which ATP is cleaved in the process of muscle activity, with the same speed are processes for its recovery.
During the hydrolysis of chemical bonds in a molecule of ATP is released a large amount of energy. For the reverse reaction recovery (resynthesis) ATP must be expended the same amount of energy, what stood out in the cleavage of ATP. The energy required for resynthesis of ATP molecules formed during the biological oxidation of various organic substances, mainly of glucose and fatty acids.