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The Biological Effects of Laser Therapy

Laser therapy is a type of photobiomodulation therapy that has a wide variety of applications that helps relieve pain and repair damage throughout the body. The power of laser therapy is in the effect it has on our bodies at the microscopic level, so in this article, we’re going to focus on the details of the biological effects of photobiomodulation therapy. 

What is Photobiomodulation?

Photobiomodulation is a process in which light is absorbed by an organism and causes a change in the organism. Photobiomodulation therapy, or PBMT, is a form of light therapy that utilizes nonionizing forms of light, such as lasers, LEDs, and broadband light in the visible and infrared spectrum. PBMT is a nonthermal process that involves endogenous chromophores which elicites photophysical and photochemical events at various biological scales.

The body’s natural processes triggered or energized by PBMT are those responsible for the alleviation of pain and inflammation, as well as immunomodulation, vascular and metabolic activity, wound healing, and tissue regeneration.

How Does PBMT Work?

Photobiomodulation therapy is a photochemical process, meaning exposure to specific wavelengths of light regulates chemical reactions in the body. PBMT is used to target the cytochrome C complex within the mitochondria of the body’s cells. This heme protein is responsible for electron transport, which is part of the synthesis of ATP (adenosine triphosphate). ATP transports energy for cellular functions, and stimulating the body’s cells through PBMT increases ATP synthesis, leading to increased cellular health and energy.

Both acute and chronic conditions respond to the photochemical mechanism provided by photobiomodulation therapy. Acute concerns, such as injury, have shorter recovery periods with PBMT treatments. When treated with PBMT, chronic conditions, like arthritis, are more manageable, and patients have a significantly improved quality of life.

Reduce Inflammation

PBMT increases inflammatory mediators, such as macrophages, neutrophils, and lymphocytes, that accelerate and resolve the inflammatory process. At the same time, PBMT reduces damaging free radical levels by increasing levels of super oxidase dismutase (SOD). This helps control painful inflammation by targeting cells and enzymes that make inflammation worse.

Long-Lasting Relief from Joint & Muscle Pain

PBMT decreases nerve sensitivity by decreasing levels of bradykinin, a pain-eliciting chemical, and has a pain-blocking effect on certain nerve fibers. PBMT also normalizes ion channels and releases endorphins and enkephalins from the brain and adrenal gland that produce an analgesic effect.

Improve Vascular Activity

PMBT provides an antiedemic effect, which causes blood vessels and lymphatic vessels to widen in a process called vasodilation. Areas treated with PBMT undergo a process of angiogenesis, or the growth of new, small blood vessels, allowing more nutrients to be supplied to an injured area and aid in the removal of dead or damaged cells. Improved lymphatic drainage also assists with reduction of excessive swelling.

Increase Metabolic Activity

PBMT creates higher outputs of specific enzymes, as well as greater oxygen and food particle loads for blood cells. This energizes cells and stimulates molecules in the target area while increasing tissue oxygenation, ATP synthesis, and intercellular exchanges. This process increases the energy available to cells so they can more readily take on nutrients and remove waste products. As a result, tendons, ligaments, nerves, and muscles are repaired faster.


PBMT has a direct effect on the immune system through stimulation of immunoglobulins and lymphocytes. Chromophores absorb and react to laser light, and the enzyme flavanone-nucleotide is activated and begins the production of ATP, a major carrier of cellular energy and the energy source for all chemical reactions in cells.

Improve Nerve Function & Regeneration

PBMT increases the proliferation of growth factors that promote neuronal sprouting and myelin formation for optimal nerve recovery. Slow recovery of nerve functions in damaged tissue can result in numbness and impaired limbs. PBMT helps improve nerve signal transmission and speeds up the process of nerve cell reconnection, increasing the amplitude of action potentials and optimizing muscle action.

Repair & Regenerate Muscle Tissue

PBMT penetrates deep into tissue and stimulates cellular reproduction and growth that repairs damaged muscle fibers. PBMT also activates myogenic satellite cells that leads to the regeneration of muscle tissue.

Accelerate Wound Healing & Reduce Formation of Scar Tissue

PBMT stimulates fibroblast development in damaged tissue, which increases collagen production that allows for proper alignment and remodeling of collagen. These processes accelerate wound healing and reduce the formation of scar tissue following damage from repetitive motion injuries, cuts, scratches, burns, or surgery. Receiving treatment early can prevent the buildup of scar tissue for torn ligaments, tendons, muscles, or post-surgery. Less tissue scarring reduces chronic pain often associated with scars.

Learn More About Photobiomodulation Therapy With Aspen Laser University

We’ve just launched our new resource library at Aspen Laser University where we’ve curated over 100 case studies and articles on laser therapy and its applications from head to toe. Click the link below to get a deep dive on PBMT for specific conditions, including traumatic brain injuries, tendinopathy, and diabetic neuropathy.

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