Heat production Initial

Heat production is the process of heat formation in body tissues due to various biological mechanisms. In sports, this term is used to describe the process of heat production in muscles in response to physical activity. Heat production is one of the key factors determining the performance of an athlete. In this article we will look at the process of heat production in muscles, its physiological basis, as well as its importance for physical training.

Heat production is the process of heat formation in the body that occurs during muscle contractions. The initial heat production phase or T0 is one of the stages of the muscle contraction process after the preliminary contractile phase. In this phase, the power of generated heat reaches a maximum, after which it gradually decreases. Initial heat production is important for muscle activity, as it is involved in maintaining the optimal muscle temperature to perform a specific job without damaging its structure.

The mechanism of initial heat production is very complex. During muscle contraction, sarcomeres, the main structures of muscle tissue, contract. At the same time, the shape of mitochondria—intracellular organelles that ensure cellular respiration and the production of ATP (adenosine triphosphate)—the main energy material for cell functioning—changes. A change in the shape of the mitochondrion leads to an increase in the concentration of ATP, which, in turn, leads to the release of hydrogen ions and stimulation of ion transport into and out of the cell, as well as to the excitation of Na/K-ATPase, the main electrolyte pump of the extracellular space. These processes increase the electrical permeability of the cell membrane and stimulate the energy-dependent transport of heat and macroergs into the cells.

Initial heat production is observed as a result of the super-energetic state of cells resulting from the accumulation of excess ATP. This condition is characterized by high activity of the enzyme creatine kinase, which plays an important role in regulating the energy balance of the cell, the breakdown of ATP and maintaining the required concentration of its molecules in muscle cells.

During the initial stage of heat production, the maximum amount of energy and heat is released. The duration of this phase is 0.2-0.4 seconds. A significant increase in the concentration of hydrogen ions released from the mitochondrial matrix converts ionized hydrogen into molecular forms, then heat is released in the form of water. In this case, heat production is maximum, approximately 80-100 J per gram of muscle mass.