Delayed onset muscle soreness (DOMS) is that burning, aching feeling in the muscle that starts one to three days after exercise. Since I want to be strong with as little pain as possible, I set out to find how red light therapy reduces DOMS muscle pain.
Using red light therapy for muscle pain reduces delayed onset muscle soreness by increasing adenosine triphosphate (ATP), increasing short burst reactive oxygen species (ROS), decreasing oxidizing ROS, and signaling the cell to reduce inflammation. Studies show that an effective dose of red light therapy reduces the inflammatory cytokines and the DOMS-based creatine kinase, effectively reducing muscle pain.
What is Photobiomodulation / Red Light Therapy / Low-Level Laser Therapy
Photobiomodulation (PBM), also known as red light therapy or low-level laser therapy (LLLT), uses specific wavelengths of light to promote healing and reduce pain and inflammation in the body. Medical professionals have been using this therapy for many years because it’s considered safe and effective.
Red light therapy involves exposing the body to red or near-infrared light. This light penetrates the skin and is absorbed by the cells, stimulating the production of energy (ATP) in the mitochondria of the cells. This helps to promote healing and reduce inflammation.
Red light therapy can be used to treat arthritis, sports injuries, and delayed onset muscle soreness pain. It’s an incredibly powerful therapy that has a transformative effect on one’s body and overall well-being.
The Biology of Red Light Therapy
RLT speeds recovery and lessens muscle pain through a number of mechanisms. The light triggers activities that result in:
- less muscle pain
- less muscle fatigue
- accelerated muscle recovery
- improved muscle performance
The mechanisms responsible for these gains include:
- increased adenosine triphosphate (ATP)
- increased short burst reactive oxygen species (ROS)
- reduces oxidizing ROS
- increased transcription factors that signal lower inflammation
To learn more about red light therapy and its many uses, see my article What Everyone Should Know About Red Light Therapy
Increased Muscular ATP
Red light therapy increases the mitochondrial production of adenosine triphosphate (ATP), the energy currency of the cell. Because muscles use so much energy, having access to more ATP improves their function.
Increased “Messaging” Short Burst ROS but Decreased Oxidizing ROS
Red light therapy results in a short burst of reactive oxygen species (ROS) but reduced amounts of damaging ROS.
In large amounts, ROS produces oxidation, which is harmful to the muscle. However, in short bursts, the mechanism is usually a message that the mitochondria send to the cell nucleus. The message the mitochondria send to the cell is to slow down the inflammation. As inflammation prevents muscle function, reducing inflammation improves muscle function.
The ROS Message is to Reduce Inflammation
Red light therapy does reduce inflammation, which is evidenced in a decrease of inflammatory cytokines, and in the case of muscles, a decrease in creatine kinase. When cytokines and creatine kinase go down, so do pain and inflammation. The ROS short burst that red light therapy sets off also triggers messaging to “transcription factors” that turn off turn down the cytokine and creatine kinase in the blood.
The Biology of DOMS Pain
Delayed onset muscle soreness (DOMS) is the muscle pain you get after exercise. It takes one to three days to show up. It’s more likely to happen if you exercise more intensely than usual. DOMS can last for days.
Delayed onset muscle soreness pain is from the same activity that grows muscle. The pain is from the same muscle fiber tears you make every time you exercise. It’s just that this time, the tears were bigger, or in a part of the muscle that was too weak to handle the load.
If you have DOMS, then that muscle has toxic waste and inflammation. One of the waste products in creatine kinase (CK). Researchers use creatine kinase levels as representative of the severity of the DOMS. When CK is high, so is DOMS. When red light therapy helps decrease CK, study subjects also report that their pain is reduced.
DOMS feels stiff, sore, and tender. Your range of motion decreases, and so does your strength. While DOMS is technically “normal,” it still hurts in a way that you want to stop.
How Using Red Light Therapy for Muscle Pain Reduces DOMS Severity
A 2017 study published in the Journal of Athletic Training[i] looked at three commercial red light therapy devices and their effect on DOMS.
The subjects did heavy-load leg extensions after the researchers treated their legs with red light therapy. One group in particular had significantly reduced DOMS pain over the next four days, compared to the other groups.
The difference in the group that did the best concerned the energy output of the lamp, and the pulsation (on-off) of the light.
Therapy Device Differences
You should know that these were not the types of devices you buy for $300 to $2500 from red light therapy companies. The asking price on this equipment starts at $10,000.
Does that make a difference to the outcome?
Supposedly, if you get the right amount of light to the muscle, the result from a lowly LED should be the same as from a gold-plated laser. Is that really the case?
There are two answers, and they’re both “maybe” or “it depends.” So long as your LED device is pointed at your muscle for an adequate time, and it has a minimum amount of power, it should do as well as an expensive laser.
This is because the slow delivery of light at the bottom end of the energy window is, according to studies, as effective as the faster delivery of light at the very top of the energy window.
The difference between an LED and a laser — and between any weak device and a stronger device — is time. So long as the LED is at least 3 watts — and assuming a number of parameters are in place to direct that 3 watts at the target — you should only have to add time to your LED treatment to obtain the same effects as the shorter laser treatment.
To learn about the at-home red light therapy devices to choose from, see my article The Complete Guide to Choosing a Red Light Therapy Device
Baseline Muscle Values
Forty young men participated in the DOMS red light therapy study. Researchers took blood samples to compare test baseline levels of creatine kinase, the enzyme associated with DOMS pain.
They then gave the men the standardized “visual analogue scale” (VAS) test to measure the subjects’ current level of soreness, pain, or discomfort.
Next, the men stretched their legs and then pedaled a stationary bike at 100 rpm for five minutes.
The researchers then recorded the subjects’ “maximum voluntary contraction” (MVC). For this test, the subjects did one very difficult leg extension. Researchers measured the force put into the lift, which created a baseline MVC to compare later after therapy and more exercise.
Muscle Pre-Treatment with Red Light Therapy
The researchers then treated the men with sham or real red light therapy. The sham group thought they were getting therapy, but the device emitted a non-bioactive light.
The remaining men received real therapy with a large dose (180 joules) of light but from three devices with different characteristics.
Group 2 was treated with a high-powered, continuous wave device. Group 3 received light from a low-powered, continuous wave light. Group 4 was treated with a low-power light that pulsed 16 times per second (16 Hz).
The DOMS Exercise and the Results
Now came the exercise to create the DOMS. The men did 75 knee extensions, using their maximum output to produce the most force possible against the weight. There were rest periods within the exercise period, but every one of the 75 reps was performed at maximum force.
At 24 hours post-exercise, the sham group, the low-power continuous wave group, and the high-power continuous wave group all experienced an increase in pain. This was the DOMS set in. Using the visual analog scale (VAS) assessment, 30 of the 40 men did not obtain a protective effect from therapy pre-treatment. Only the low-powered pulsed laser reduced the pain.
What this shows is that red light therapy does reduce DOMS when applied in the right dose. Dosing is the Achilles’ Heel of getting good results. It’s so easy to do therapy for too long or for too short of a time, or to put the light too close or too far away from the target.
The study showed that had everyone has been treated with the low-powered pulsed light, everyone would have received significant relief from the onset of DOMS. The pulsed-light group’s VAS score fell significantly at 24 hours, 48 hours, and 96 hours after the exercise.
What went wrong with the continuous wave groups that they did only as well as the sham treatment group?
We can guess, but we don’t know. Perhaps 180 joules is too much light: the cells can only absorb that much energy if the device delivers it with tiny breaks in delivery.
Perhaps the problem was the continuous wave as compared to the pulsed delivery of light. That is possible, but there are so many studies in which continuous wave, non-pulsed light does deliver a positive result.
One clue comes from the creatine kinase results. The low-power continuous wave and the low-power pulse groups experienced a significant decline in creatine kinase, indicating a lower level of DOMS. But the high-power, continuous wave group had a significant increase in creatine kinase above the baseline levels!
This indicates that the high-power device was too high-powered. It delivered light above the high end of the low-energy window.
This study proved that the right dose of red light therapy reduces DOMS and creatine, and the wrong dose makes matters worse.
The MVC results show whether the men were weak or strong after the test. The two low-power light groups were significantly stronger during the four days post-exercise. The pulsed group did the best. The high-power light and the sham group were weak after the exercise test.
The DOMS Biology Results
The high-power light group had significantly more creatine kinase compared to the baseline. Their capacity for DOMS pain went up, the opposite of the desired result. The low-power continuous wave group saw a significant CK drop only at the 48-hour post-exercise mark, not at 24 hours, 48 hours, or 96 hours. The low-power pulsed group had a significant CK drop starting at 24 hours that they maintained through the 96-hour mark.
Please remember that we are still in the infancy of figuring out optimal doses, which is what makes this study so valuable. The results add to the parameter literature that at 180 joules, the low-power continuous wave is marginally effective, the high-power continuous wave is detrimental, and low-power pulsed light hits the sweet spot of reducing DOMS pain. Red light therapy helps with chronic pain too. Learn about that in my article What Happens When You Use Red Light Therapy for Chronic Pain?
[i] De Marchi T, Schmitt VM, Danúbia da Silva Fabro C, da Silva LL, Sene J, Tairova O, Salvador M. Phototherapy for Improvement of Performance and Exercise Recovery: Comparison of 3 Commercially Available Devices. J Athl Train. 2017 May;52(5):429-438. doi: 10.4085/1062-6050-52.2.09. Epub 2017 Mar 20. PMID: 28319422; PMCID: PMC5455246.