How Does Lasers Work?

Light energy from a cold laser is is absorbed by either chromophores or photoacceptors on the mitochondrial membrane ( cytochrome c oxidase and nitric oxide synthase are particularly reactive to laser stimulation). In animals and humans the most affective wavelength are in the red and near infrared light range. Stimulation increases ATP (cellular energy source) as well as nitric oxide. The results of this stimulation is the increase of cellular metabolism, circulation, and nerve function.

Low level laser therapy helps in the treatment of neuromusculoskeletal conditions in three ways: (From Richard Martin in Practical Pain Management, Nov/Dec 2003)

1. Anti-Inflammation

• Stabilization of cellular membrane Ca, Na, K, concentrations

• Production and synthesis of ATP is enhanced

• Vasodilation reduces ischemia and increases perfusion

• Acceleration of leuckocytic activity

• Increased prostaglandin production

• Reduction in Interleukin 1

• Enhanced lymphocyte response

• Increased angiogenesis for both blood and lymphatic capillaries

• Temperature modulation

• Enhanced Superoxide Dismutase levels

• Decreased C reactive protein levels

2. Pain Reduction

• Increase in b-Endorphins

• Suppression of C fibre afferent excitation

• Increase in Nitric oxide production

• Restoration of nerve cell action potential

• Axonal sprouting and nerve cell regeneration

• Decreased bradykinin levels

• Increased release of acetylcholine

• Normalization of Ca, Na, and K ions concentrations

3. Tissue Healing

• Enhanced leukocyte infiltration

• Increased macrophage activity

• Increased neovascularization

• Increased fibroblast proliferation

• Keratinocyte proliferation

• Early epithelialization

• Growth factor increases

• Enhanced cell proliferation and differentiation

• Greater healed wound tensile strength

Cells and tissue that are damaged because of ischemia, inflammation and swelling appear to be more receptive to the photons compared with normal healthy cells. Therefore, laser seems to target damaged cells vs healthy cells.