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You might have seen the ads and heard others mention using light for pain relief and healing.
If you read this recent Smart Chiropractor blog, you noticed that laser therapy was recommended in the clinical practice guidelines for chronic neck and lower back pain.
But is laser therapy truly a beneficial modality?
How does non-invasive light do anything to the tissues?
Is it just a fancy placebo?
Many chiropractors (and patients alike) are left to wonder, “How does laser therapy work?”
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Let’s define laser therapy quickly…
Laser therapy uses light to produce a specific stimulatory effect on biological tissues, usually repair, regeneration, and pain reduction.
Using laser and LED light to stimulate the body’s healing mechanisms is now termed “photobiomodulation.”
But for this post, I’m going to use the much sexier term “laser therapy” mostly.
People have been wondering if and how does laser therapy work since the 1960s.
It was way back when that a Hungarian surgeon named Endre Mester accidentally found that red lasers stimulated faster hair growth in mice.
Since then, over 4000 studies have been conducted on hundreds of conditions (nearly 400 studies were published in 2020 alone).
Overwhelmingly, the studies demonstrate excellent safety, and in many cases, good effects on painful conditions.
I’ll get back to this at the end.
First, we need to shed some light on a few things (no pun intended).
So, how does laser therapy work?
Let’s dig in.
For light to affect tissues, you need three things…
- Absorption of light energy by critical cellular components.
- Penetration of light to the tissues’ depth to be affected.
- An adequate dose delivered to that depth.
An Introduction: How Does Laser Therapy Work?
This is a bit complex, so let’s break these down one at a time.
Laser Therapy Absorption
Light is absorbed by colored matter that matches the light’s wavelength.
Think about wearing a dark shirt outside on a sunny day – you’ll get much warmer than you would with a light-colored shirt because the dark material absorbs the sun’s UV and far-infrared waves more easily.
“Colored” chromophores absorb wavelengths in the 640-1100nm spectrum (visible red through near-infrared) in human cells.
Two of these chromophores are cytochrome C oxidase and mitochondrial-bound water molecules, essential components in the mitochondrial production of ATP.
When CCO and bound water absorb this near-infrared light, they change 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 vasodilation that improves the transport of oxygen and immune cells to the tissue leading to enhanced cell repair.
Red and infrared light enhances phagocytosis, angiogenesis, collagen synthesis, keratinocyte, and fibroblast proliferation.
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 injury.
Laser Therapy Penetration
Most people don’t think light can travel through the tissues, but the right kind of light definitely can.
Think about shining a flashlight through one side of your hand and seeing your hand glow red- that’s an example of light penetrating the tissues and even coming out the other side.
Near-infrared light at 800-1100nm can go quite deep into the tissues, even going right through bone! Good penetration of light allows the absorption of photons in deep tissue injuries, and as we saw above, these wavelengths produce multiple beneficial cellular effects.
One thing before we move on, even with good penetration, light is absorbed and diffused into the tissues, and you get less and less light the deeper you go.
Laser Therapy Dose
The right dose of light is the third important factor.
Take exercise dosing as an example.
Working out too briefly with minimal exertion will get you almost no results, but going too hard for too long results in more soreness and less benefit.
Laser dosing is similar in that doing too much or too little will result in minimal effects.
Laser dosing is measured in Joules, and most experts have settled on the proper dosage of laser being 4-10J/cm2, meaning that if you have a 10 x 10 cm area to treat, your total dose should be 400-1000 Joules total.
This is something your laser device should show you.
Now the difficulty with proper dosing comes about when you start thinking about the depth of the issues you want to treat.
Superficial painful wound? 4 J/cm2 should work well.
What about a lumbar disc? Or the hip joint? You’ll need to deliver 4-10 J/cm2 to that depth! That means you can no longer look at the total superficial area for dose calculation.
You’ll need much higher amounts of light to get effective doses that deep.
But relax—most high-end lasers will have presets that do a lot of the work for you.
Laser devices are divided into classes based on their power output.
There are two main types that you’ll find in a PT or chiropractic office: Class 3 and Class 4 units, with class 3 machines producing 0.5 watts or less and class 4 lasers producing more than 0.5 watts.
Both classes of therapy lasers are safe to operate.
The main difference between the two classes is that class 4 units deliver their doses faster than class 3 machines.
A quick example: providing 400 J with a 0.5W class 3 machine will take more than 13 minutes, while a 5W class 4 machine will take less than 2 minutes.
This higher power is important when treating injuries to deeper tissues such as ligaments, muscles, tendons, and cartilage.
Beam intensities greater than 1W significantly improve light transmission through soft tissues when compared with lower beam intensities.
Several published reports have questioned low-power lasers’ ability to transmit energy beyond the skin into deep tissues effectively.
Now that we’ve checked the box for properly exploring the question “How does laser therapy work?”, you may recall I talked about evidence for laser therapy’s effectiveness at the top, and I won’t leave you hanging. Here are just a few quotes I picked out.
For my complete database of research, click here.
- Neuropathy: Laser therapy “has beneficial effects on the recovery of nerve lesion, especially when related to a faster regeneration and functional improvement.”
- Headaches: Laser for chronic migraines is just as effective as botox injections while being cheaper and reducing sleep disturbance better.
- Musculoskeletal Conditions: 94% of articles included in this study on class 4 laser for musculoskeletal pain revealed positive effects.
- Athletic Performance: Light therapy produces better muscle recovery and strength gains post-exercise than ice while still reducing soreness.
- Complex Diseases: Light therapy can raise the standard of care and improve patients’ quality of life for a fraction of the cost of many current approaches. “Progress will lead to the imminent inception of light therapy as a mainstream treatment for multiple complex diseases… it is time to begin considering light therapy as a potential drug equivalent.”
In Review: How Does Laser Therapy Work?
So, in summary, how does laser therapy work? Specific colors of light induce faster ATP production, increasing NO and ROS, causing vasodilation for improved blood flow and cellular repair.
This means that laser therapy, when used with the right equipment and techniques, can produce good results in dozens of conditions, from neuropathy to arthritis to acute injuries.
Because you’re merely accelerating the body’s natural healing processes, this perfectly aligns with the drug-free natural healing philosophy that most of us chiropractors operate with.
Light therapy reduces pain, so the consumption of pain killers and anti-inflammatory pharmaceuticals with long-term side effects can be reduced.
How Does Laser Therapy Work for Chiropractors?
Laser therapy enables us as chiropractors to amplify patient results, and of course, patient results drive patient referrals.
The laser also provides an additional revenue stream that, in many cases, is reimbursed by insurance companies and is legal for chiropractors to operate in all 50 states.
Lastly, by adding laser therapy to their practice, chiropractors expand the spectrum of conditions that can be addressed through natural, drug-free methods.
Look, merely buying a laser won’t guarantee patient results and financial success.
Along with the right laser equipment, you also need to have the right training and protocols, and figuring all that out can be daunting.
I founded Laser Therapy Institute to provide that training because laser is an excellent tool for non-invasive practitioners like chiropractors.