LASER THERAPY MECHANISMS OF ACTION
Laser therapy uses an induced emission of electromagnetic radiation to transfer energy to biological cells to stimulate photobiomodulation. For those photons to produce a biological response, they must be absorbed by the tissue. Chromophores absorb the light, which produces biological reactions.
• High-intensity laser therapy, also known as Photobiomodulation therapy (PBMT) can result in beneficial therapeutic outcomes such as the alleviation of pain, increased blood flow, muscle relaxation, and relief from joint stiffness. 3-4 Relieving pain and increasing muscle relaxation allows patients suffering from back and neck conditions to get more out of their therapy program which can lead to improved outcomes and an accelerated recovery. • PBMT is a form of light therapy based on the photochemical process called photobiomodulation (PBM). In PBMT, a light source is placed near or in contact with the skin. The light energy penetrates the skin, reaching the cell’s mitochondria and creating a cascade of biological responses. PBM-Mechanisms of Action The application of a therapeutic dose of light to impaired or dysfunctional tissue leads to a cellular response mediated by mitochondrial mechanisms involved in pain relief and tissue repair processes. 4 The primary target for the process is the cytochrome c complex which is found in the inner membrane of the cell mitochondria. Cytochrome c is a vital component of the electron transport chain that drives cellular metabolism. As light is absorbed, cytochrome c is stimulated, leading to increased production of adenosine triphosphate (ATP), the molecule that facilitates energy transfer within the cell.
In addition to ATP, laser stimulation also produces free nitric oxide and reactive oxygen species. Nitric oxide is a powerful vasodilator and an important cellular signaling molecule involved in many physiological processes. Reactive oxygen species have been shown to affect many important physiological signaling pathways including the inflammatory response. In concert, these molecules have been shown to increase growth factor production and promote extracellular matrix deposition. The resultant increase in cell proliferation and motility leads to pro-survival pathways for the cell. 4-6 Many electrotherapy interventions claim to influence pain but only a few have direct influence on nociceptors. LightForce Therapy is one of those and can provide both immediacy and long term pain relief. 7
The Thermal Effect of HILT Melanin, hair follicles, chromophores, and other superficial absorbers attract and absorb light during photobiomodulation treatments. The heat produced by class IV lasers is considered superficial heat. It will increase skin temperature, thus producing an additional analgesic effect. The thermal effect provides additional value to the biological process of photobiomodulation.
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