You may have seen and heard the commercials about light being used for pain relief and healing. Laser therapy is recommended in clinical practice guidelines for chronic neck and back pain.
But is laser therapy really a useful method?
How can non-invasive light do anything to tissue?
Is it just a fancy placebo?
Many patients wonder, "How does laser therapy work?"
Let's define laser therapy briefly...
Laser therapy uses light to produce a specific stimulating effect on biological tissue, usually for repair, regeneration, and pain relief.
The use of laser and LED light to stimulate the body's own healing mechanisms is now known as "photobiomodulation".
Since around the1960s, people have been wondering if and how laser therapy works.
It was a long time ago when a Hungarian surgeon named Endre Mester accidentally found out that red laser stimulates faster hair growth in mice.
Since then, over 4000 studies have been conducted on hundreds of diseases (nearly 400 studies were published in 2020 alone).
The overwhelming majority of studies show excellent safety and, in many cases, good efficacy for painful conditions.
So, how does laser therapy work?
In order for light to affect tissue, you need three things....
1. the absorption of light energy by important cellular components.
2. penetration of the light into the depth of the tissue to be affected.
3. appropriate dose to reach this depth.
An introduction: how does laser therapy work?
Laser therapy absorption
Light is absorbed by colored material that corresponds to the wavelength of the light.
Imagine wearing a dark shirt outside on a sunny day - you'll be much warmer than with a light shirt because the dark material absorbs the sun's UV and far-infrared waves more easily.
"Colored" chromophores absorb wavelengths in the 640-1100 nm spectrum (visible red to near-infrared) in human cells.
Two of these chromophores are cytochrome C oxidase and mitochondria-bound water molecules, which play important roles in ATP production in mitochondria.
When CCO and bound water absorb near-infrared light, they change their conformation and position, which increases the rate of ATP formation.
This process also releases limited amounts of nitric oxide (NO) and reactive oxygen species (ROS), which activate transcription factors for growth factors and mediator proteins involved in wound healing.
NO also causes vasodilatation, which improves the transport of oxygen and immune cells to tissues, promoting cell repair.
Red and infrared light promotes phagocytosis, angiogenesis, collagen synthesis, and proliferation of keratinocytes and fibroblasts.
Laser therapy-induced changes in blood flow and microcirculation promote healing by controlling ischemia, hypoxia, and edema after injury and creating a favorable biological repair environment after musculoskeletal injuries.
Laser Therapy Penetration
Most people don't believe that light can penetrate tissue, but with the right kind of light, it's definitely possible.
Imagine shining a flashlight through one side of your hand and seeing your hand glow red - that's an example of light penetrating the tissue and even coming out the other side.
Near-infrared light with a wavelength of 800-1100nm can penetrate quite deep into tissue and even penetrate bone! Good penetration of light allows absorption of photons in deep tissue lesions, and as we have seen above, these wavelengths have several beneficial effects on cells.
Before we go any further, one more note: Even with good penetration, the light will be absorbed and scattered in the tissue, so you will get less and less light the deeper you go.
Laser Therapy Dose
The correct dosage of light is the third important factor.
Take the dosage of sports as an example.
If you exercise too short and with minimal effort, you will get almost no results, but if you exercise too long, you will get more pain and less benefit.
It is similar with the dosage of laser light: if you exert yourself too much or too little, you will get minimal effects.
Laser dose is measured in joules, and most experts have agreed on a dose of 4-10 J/cm2. This means that if you want to treat an area of 10 x 10 cm, your total dose should be 400-1000 joules.
This is what your laser device should show you.
How does laser therapy work? Laser therapy dose
The difficulty in finding the right dosage comes when you think about the depth of the problems you want to treat.
Superficial, painful wound? 4 J/cm2 should work well.
What about a lumbar disc? Or the hip joint? Then you need to deliver 4-10 J/cm2 to that depth! That means you can no longer look at the entire superficial area when calculating dose.
You need a much higher amount of light to achieve an effective dose at that depth.
But don't worry - most high-end lasers have presets that do much of the work for you.
Laser Types
Laser devices are divided into different classes based on their power.
There are two main types you will find in a PT or chiropractic practice: Class 3 and Class 4 devices. Class 3 devices have a power output of 0.5 watts or less, while Class 4 lasers produce more than 0.5 watts.
Both classes of therapy lasers are safe to use.
How Does Laser Therapy Work: Safety
The main difference between the two classes is that Class 4 devices deliver their dose faster than Class 3 devices.
As a quick example, delivering 400 J with a 0.5 W Class 3 device takes more than 13 minutes, while a 5 W Class 4 device takes less than 2 minutes.
This higher output is important for treating injuries in deeper tissues such as ligaments, muscles, tendons and cartilage.
Beam powers greater than 1 W significantly improve the light transmission of soft tissue compared to lower beam powers.
Several published reports have questioned the ability of low-power lasers to effectively transmit energy beyond the skin into deep tissue.
Prove it!
Quotes from current research
Neuropathy: Laser therapy "has positive effects on the recovery of nerve lesions, especially in terms of faster recovery and functional improvement."
Headaches: laser for chronic migraine is as effective as Botox injections, but is cheaper and better at reducing sleep disturbances.
Musculoskeletal: 94% of the articles in this study of Class 4 lasers for musculoskeletal pain showed positive effects.
Athletic performance: light therapy results in better muscle recovery and strength increase after exercise than ice, while reducing muscle soreness.
Complex diseases: Light therapy can raise the standard of care and improve patients' quality of life at a fraction of the cost of many current methods. "Advances will soon lead to the adoption of light therapy as a standard treatment for many complex diseases.... it is time to consider light therapy as a potential medication.
In review: How does laser therapy work?
In summary: How does laser therapy work?
Certain colors of light cause faster ATP production, increase NO and ROS, and cause vasodilation, which improves blood flow and cell repair.
This means that laser therapy, when used with the right equipment and technique, can provide good results for dozens of conditions, from neuropathy to arthritis to acute injuries.
Since you're just accelerating the body's natural healing processes, it fits perfectly with the drug-free natural healing philosophy that most of us chiropractors work with.
How does laser therapy work for chiropractors?
Light therapy relieves pain, reducing the use of painkillers and anti-inflammatory medications with long-term side effects.
Laser therapy allows chiropractors in Victoria BC, such as Dr. Mike Hadbavny to improve patient outcomes and improve quality of life.
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Dr. Mike Hadbavny
Victoria Sports Chiropractor FRCCSS(C)
If you are interested in learning more about how chiropractic care can be effective for your particular condition or health goals, contact Dr. Mike Hadbavny at 250-881-7881 today to make an appointment and discover the many benefits of seeing a chiropractor in Victoria BC. Contact us today.