Infrared therapy mainly uses the thermal effect and non-thermal effect of infrared to improve the physiological function and pathological state of the human body. The specific principles are as follows:
Thermal effect principle
Molecular vibration heat generation
Infrared is an invisible light with a frequency between microwaves and visible light. Various molecules in human tissues (such as proteins, nucleic acids, fats, etc.) will vibrate under the irradiation of infrared rays. Because the energy of infrared photons can be absorbed by these molecules, the kinetic energy of the molecules increases, which in turn causes the molecular vibration to intensify. This vibration generates heat, just like we feel hot when we rub our hands.
For example, when water molecules are exposed to infrared rays, the vibration amplitude of their hydrogen-oxygen bonds increases, and the thermal motion of the molecules increases, thereby increasing the temperature of local tissues. The water content in tissues such as skin and muscles is high, so infrared rays can quickly heat up these tissues.
Accelerated blood circulation
When the temperature of local tissues rises, a series of physiological reactions will occur. First, the increase in temperature will cause blood vessels to dilate, especially capillaries. This is like heating a water pipe and causing it to expand and thicken. After the blood vessels dilate, the resistance to blood flow decreases and the blood flow speed increases.
For example, infrared therapy is performed on the site of muscle strain. As the temperature rises, the blood vessels in the muscle tissue expand, and more blood can carry oxygen and nutrients to the damaged muscle cells. At the same time, metabolic wastes, such as lactic acid, can be transported more effectively, thereby relieving muscle fatigue and pain.
Enhanced metabolism
As blood circulation accelerates, cell metabolism is also enhanced. Cells can obtain more sufficient oxygen and nutrients, and their metabolic activities are more active. For example, with sufficient oxygen supply, the mitochondria in the cell can perform aerobic respiration more efficiently and produce more energy (ATP) for various physiological functions of the cell.
At the same time, the discharge of metabolic waste is also smoother, which helps to maintain the stability of the intracellular environment. For some chronic inflammatory sites, enhanced metabolism can promote the disappearance of inflammation and the repair of tissues.
