LED Heat Lamp Therapy Part 2: Temperature Dosing
A type of Radiant Heat Therapy is called Water Filtered IRA (wIRA). It uses a broad spectrum Near-Infrared halogen incandescent emitter with mostly non-thermal NIR wavelengths (thanks to the water filter).
Typical intensities of wIRA are 80-160 mW/cm^2 delivered in a large area with mostly Red and NIR wavelengths. [1]
This intensity range should be recognizable, as it is similar to the range we are currently seeing in many "highest intensity" LED red light therapy panels, that we affectionately call more appropriately as LED Heat Lamps.
The wIRA therapy attributes the benefits to both thermal and non-thermal mechanisms.[1] However, despite using NIR wavelengths that could be for Photobiomodulation, they know that wIRA wouldn't fit in the category of LLLT/PBM since it is a heating therapy.
wIRA states the minimum dose is 20 minutes to raise the skin surface temperature by about 6C up to about 39C.[1] Well below any safety concerning high temperature 43-45C while still maintaining therapeutic heating.
Even at the lowest dose of 80mW/cm^2 for 20 minutes, that is an Energy Density of 96 J/cm^2. Which would often be considered inappropriate for Photobiomodulation.
Luckily for us, heat therapy doesn't follow the Law of Reciprocity. That is the law of photochemistry that allows us to calculate "dosage" based on Energy (Joules or J/cm^2) by the multiplication of Intensity and Time.
One study on wIRA states this plainly:
"the Bunsen-Roscoe law of reciprocity (which states that a certain biological effect is directly proportional to the total energy dose irrespective of the administered regime) cannot be applied to the thermal effects of IR radiation in tissue"
[2]
Since most of the photons will be converted to heat, we can throw away the dosing calculations for J/cm^2 or Joules.
As one Photobiomodulation review article clearly states:
"Using higher intensity, the photon energy will be transformed to excessive heat in the target tissue"
[3]
High intensity photons being converted into heat is derogatory in the context of LLLT/PBM which are non-thermal, and those photons cannot be counted towards the energy dosing calculations.
"At low irradiances and/or energies, laser-tissue interactions are either purely optical or a combination of optical and photochemical or photobiostimulative. When laser power or pulse energy is increased, photothermal interactions start dominating."
[4]
As the quote above tells us, high irradiances (intensity) will cause heat mechanisms to dominate, not the photochemical and photobiostimulative mechanisms from true "cold" LLLT/PBM at lower intensities.
Essentially, "High Intensity Red Light Therapy" simply becomes Radiant Heat Therapy by converting photons to heat and triggering the thermal mechanisms to dominate. Or perhaps another name for this new science could be PhotoThermalBioModulation. Inserting the word Thermal into PBM to make it clear when heat is being utilized.
Our previous blog covered using LED Heat Lamps as an energy therapy. However, this blog will cover how they could be more appropriately used as what they are - a heat therapy.
As we can already see, wIRA is a much closer science to LED Heat Lamps than anything else. LED Heat Lamps have reverse-engineered wIRA, and pushed themselves out of the categories of non-thermal LLLT/PBM.
Summary - Dosing For Temperature:
The most important dosing technique with LED Heat Lamp therapy is to monitor skin temperature during treatment. This makes sure you are in the proper therapeutic heating zone and monitor for excessive temperature to avoid damage. We use the Berrcom Non-Contact Infrared Thermometer from Amazon.
LED Heat Lamps could be dosed similarly to the research on wIRA and Passive Heat therapies that we can find on PubMed.
A safe heat therapy range is typically between 38 to 41 °C for therapeutic passive heat therapy, typically sustained for 15-90 minutes per treatment.
This is assuming a normal starting skin temperature around 34-36 °C. Meaning typically we look for a skin temperature increase of about 2-6 °C for therapeutic heating. Temperatures up to 42 °C may be acceptable for some contexts or treatments. However typically 41-43 °C are a precautionary range.
Temperatures above 43-45 °C will typically cause a burning sensation and heat pain - sustained or repeated exposure at this temperature could be deleterious unless under medical supervision.
Applications: The best known applications of heat therapy are for temporary pain relief, muscle relaxation, wound healing, inflammation reduction, workout recovery, skin tightening, fat loss, circulatory and cardiovascular health, and more.
Safety: Naturally heat therapy runs the risk of burns if using excessive temperatures for long periods of time or repetitively. Erthyma Ab Inge is a hyperpigmentation response that can occur from sustained or repeated heat therapy. Erthyma is the skin redness from heat or inflammation of the skin similar to sunburn. Blood pressure drops from Nitric Oxide release may be a precaution with people with hypotension (low blood pressure).
Heat Therapy Types:
Heat therapy can be delivered by fire, sunlight, hot water bottles/bladders, hot water baths, heating suits, infrared heat lamps, saunas, electric heat pads, ultrasonic, radio frequency (RF), high powered lasers, incandescent bulbs, wIRA, and now high-powered LED panels.
Many brands and influencers have proposed using LED Panels as a form of heat therapy. But we need to apply real scientific parameters to this rhetoric. How much heat? What temperature? How long should we sustain the temperature dosage?
Like considering any drug or light therapy, we must look at the proper parameters of heat therapy. Typically the temperature and exposure time are the most important to heat therapy. Then how often/frequently it is used and how many treatments are required.
As one heat therapy explains about the considerations needed:
"To optimize heat therapy, future studies could use the principles of exercise prescription [frequency, intensity, time and type (mode)] in the context of passive heating (Cullen et al., 2020)."
[5]
Similarly, we need to establish some basic parameters and education how to optimize LED Heat Lamp therapy. Which likely follow similar parameters as wIRA and Passive Heat Therapy.
Dosing Radiant Heat Therapy vs Light Therapy:
Radiant Heat Therapy must be dosed differently than Cold Light Therapy, and naturally has different protocols and safety considerations.
Dosing "cold" LLLT/PBM:
- Uses Energy (J/cm^2) delivered by Intensity (mW/cm^2) and Time (seconds or minutes) for dosing.
Dosing Heat Therapy:
- Maintains an elevated target tissue temperature (38-41 C) for an allotted amount of time (minutes or hours)
Regardless of the type of heat therapy, the main objective is simply to elevate the tissue temperature for the proper amount of time.
While understanding the intensity of an LED Heat Lamp is important as a general indicator, every person will respond differently based on skin tone, skin thickness, and circulation. The skin temperature should be monitored with a thermometer for best results.
Passive Heat Therapy Treatment Protocols:
Similar to wIRA, an emerging therapeutic field is simply called Passive Heat Therapy. This is using various forms of heating to promote healing. Sometimes for spot treatments or whole-body heating.
"Passive heating methods have been used to increase core and/or muscle temperature via different temperature and exposure time, depending on their mechanistic target (e.g., part- or whole-body heating). Hyperthermia is achieved with low-temperature applications (e.g. < 41 °C applied for about 60 min) that increase blood flow and metabolic rates (Habash et al., 2006b), while interventions targeting cellular death (e.g., tumours) via heat-induced protein denaturation require hotter applications (Raaphorst, 1990)."
[6]
One passive heat therapy study utilized a hot bath of 40C (104F) for 20-30 minutes 3 times a week for osteoarthritis.[7]
It is important to keep in mind that therapeutic heating is usually capped at 41C. The consumer has a right to informed consent if they are getting an LED heat lamp, and be informed how to use it safely and effectively.
History of Heat Therapy:
None will deny that Heat Therapy is very beneficial and effective, in fact, it may be one of the oldest known therapies to humankind.
The internal process of inflammation has its root word in latin meaning "flame". It was coined by Roman physician Cornelius Celsus when observing the redness, swelling, heat, and pain from an injury. [8] Which we now know inflammation triggers healing mechanisms.
More famously, is the body's usage of fever is to raise internal temperature to fight infection. Hippocraties is credited to saying that if given the power to induce fever then he could could cure any illness.
Yes, the power to use heat to heal has been inside us all along. It is an innate part of our biology.
However, humans quickly learned that externally applied heat can also stimulate a healing response. Thus, heat therapies have emerged even in ancient civilizations.
Another quote from Hippocrates is as follows:
"“those who cannot be cured by [medicine or] surgery can be cured by heat; and those who cannot be cured by heat are to be considered incurable”."
[9]
Many passive heat therapy studies introduce themselves by referencing Hippocrates:
"The use of thermal therapies involving passive heating has occurred since the time of Hippocrates (Papaioannou et al., 2016). Since then, passive heating has been therapeutically administered as part of various cardiovascular, metabolic, oncological, and other health treatments (Brunt et al., 2016; Habash et al., 2006a; Maley et al., 2019; Pallubinsky et al., 2017)."
[6]
Here is a quote saying Heat Therapy being credited as being centuries old, we would say heat therapy is actually many millennia old.
"Passive heat therapy is in fact not novel but centuries old, historically used as a form of healing to treat health conditions such as rheumatism and skin conditions (Fagan, 2006; Lehtmets, 1957; Nicholls & Harwood, 2017)."
[10]
This lack of novelty has led many companies selling LED Heat Lamps to promote themselves as Red Light Therapy instead.
Although Heat Therapy is tested by time and well-recognized as beneficial, it is more marketable to piggy-back claims on a newer type of therapy like Photobiomodulation, even though PBM is explicitly defined as non-thermal.
Amazingly, brands have accidentally re-invented heat therapy with new LED technology. It's like the old saying of re-inventing the wheel, except heat therapy is also older than the wheel.
Benefits of Heat Therapy:
Conventionally heat therapies are utilized for wound healing, muscle relaxation, and temporary pain relief.
Whole-body heat therapies like sauna and hot baths are known for supporting cardiovascular health, brain health, mental health, and detoxification.
Similar to Red Light Therapy, Passive Heat therapies are also getting a lot of attention in recent Pubmed studies and articles.
Articles like these are very positive torwards the many benefits of heat therapy.
2016: Passive heat therapy: the next hot thing for cardiovascular health!
2017: Heat: A New Approach to Treating Depression?
2021: Heat therapy: mechanistic underpinnings and applications to cardiovascular health
Even a low level laser therapy study acknowledges the benefits of heat:
"Use of applications that increase the temperature of muscle tissue in the physiotherapy clinic generates many therapeutic effects such as vasodilation (dilation of blood vessels), promoting blood flow, muscle cell activation that can encourage relaxation, tissue renewal that helps promote DNA synthesis and therefore cell proliferation [12]-[14]."
[11]
And another one notes that small temperature increases are used in skincare and dermatology:
"Indeed, it is recognised by the dermatology community that a small incremental rise in temperature of 1–2 °C can enhance the quality of healing processes [73,74]." [12]
We expect the clinical studies on Heat Therapy will rapidly expand similar to Red Light Therapy, especially with the many new technological methods available apply heat therapy.
Mechanisms of Heat Therapy:
One of the most exciting things about Photobiomodulation is the mechanisms of improving mitochondrial function and using fancy words like CytoChrome C Oxidase, Chromophores, and Electron Transport Chain.
Perhaps if we can uncover some equally exciting mechanisms for heat therapy, then brands will be brave enough to promote themselves properly as the LED Heat Lamps that they are.Despite being a very old form of therapy, the mechanisms of heat therapy are not fully understood.
"That said, there is much that we still do not know, and more studies on the mechanisms that underpin the benefits of passive heat therapy are warranted."
[13]
However, with a lot of recent research on the topic of heat therapies, here are many mechanisms we could find:
- Activate heat-gated ion channels and promote cell proliferation and ATP production. [14]
- promote increased NO bioavailability. [5]
- release of heat shock proteins (HSP70 and HSP90) [5]
- heat stress (40°C, 60 min/day, 5 days) induces mitochondrial biogenesis [15]
- muscle growth also occur during physiological hyperthermia (increased core temperature) [6]
- changes in gene expression (i.e., upregulated polypeptide 1 myosin, heavy polypeptide 2 myosin and alpha 1 actin (Guo et al., 2016) [6]
- anti-inflammatory and antioxidant effects (Takeuchi et al., 2014; Vardiman et al., 2015) [6]
- improves glucose metabolism (Hoekstra et al., 2018) [6]
- heat shock protein (HSP) expression (e.g. HSP27, HSP70, HSP72 and HSP90) (Castellani et al., 2016; Ogura et al., 2007) [6]
- passive heating can promote cell proliferation and induce muscular hypertrophy (Goto et al., 2004; Naito et al., 2000; Uehara et al., 2004). [6]
- "An elevation in tissue temperature of just 1 °C is associated with a 10–15% increase in the local metabolism. " [19]
Many of these mechanisms and benefits should sound familiar to LLLT/PBM.
It would be the perfect crime to sell high-intensity LED Heat Lamps under an exciting new category of LLLT/PBM Red Light Therapy - and the consumer won't notice the difference that they actually got a Heat Lamp as long as they get similar results.
Safety of Heat Therapy
Brands registered at Medium-Risk Class II Heat Lamps under the ILY code have a medical obligation to provide informed consent to their customers and patients of possible risks of heat therapy.
"How safe is it? No side effects were reported in the studies, but in general, studies report that thermotherapy is safe when applied carefully."
[16]
Carefully applied heat therapy is indeed extremely safe. Keyword being "carefully".
Unfortunately, if the manufacturers aren't designing devices properly and not properly educating the consumer with informed consent, then improperly applied heat therapy is certainly problematic. As we know sustained temperatures of >45C causes deleterious effects.
One wIRA study describes how they monitor skin temperature during treatment with 185 mW/cm^2 of Red and NIR.
"During some of the treatments the skin surface temperature of the treated skin area was continually monitored by the infrared camera. On other occasions the skin temperature was periodically checked during the treatment using a Raytek Raynger MX4 high performance non-contact hand held infrared thermometer (Raytek, Berlin, Germany). Skin surface temperature was not allowed to increase above 41°C. "
[17]
Then they increase the distance (and thus decrease irradiance) to manage the temperature properly or if the patient felt unpleasantly warm.
"On the few occasions that the patient felt that the skin surface temperature was uncomfortably high, the irradiation distance was increased by approximately 5–10 cm. "
[17]
Assuming the temperatures are monitored (<41C) and intensities and exposure times are not excessive. Then generally heat lamp therapies can be safely administered with proper training and awareness.
One study with wIRA showed unsafe heating with 250mW/cm^2 in less than 10 minutes to reach 43C. [18]
Which is likely why they found 80-160 mW/cm^2 is the ideal range for the proper amount of heating. So even with heat therapies, there is a limit to the appropriate amount of intensity.
Most people are aware of the risks of burns with heat therapy. Which is why skin temperature monitoring is crucial. As studies do clearly recognize that prolonged and/or excessive heat exposure has safety hazards. [5]
Temperature Profiles for LED Heat Lamps
In some extremely boring YouTube videos, we documented the first attempted usage of high intensity LED panels as a potential for theraputic heating.
We had custom-made high intensity LED panels made with single-wavelengths to test the effects of different wavelengths and intensities on the heating profile. We also tested on high-intensity LED Heat Lamp from AliExpress.
On the chart above, we see the individual wavelengths at high intensity 105-115 mW/cm^2. While we want to be in the optimal heat therapy zone 38-41 C, we see within only 4 minutes all of the wavelengths caused heating past the ideal theraputic zone. So ironically intensities >100mW/cm^2 are not only inappropriate for Photobiomodulation, but these intensities may also be too much for even a heat therapy usage.
Now at intensities between 54-61mW/cm^2 we see a much more gradual heating up period. So this range may be more ideal for a heat therapy, with proper monitoring and adjusting the distance if the temperature gets too high.
Notice how the 630nm and 660nm Red wavelengths deliver significantly more heating than the Near-Infrared wavelengths.
This has been well documented that Red is more heating than NIR. And as we recommended previously that NIR will be required for high-intensity devices to reduce superficial skin heating that is caused by Red. So if you have a high-intensity LED Heat Lamp already, it is better to turn off the Red to reduce heating.
With a 5-wavelength panel from AliExpress with 69mW/cm^2 shows a nice temperature profile that stays in the theraputic range. The plateau of temperature that we see in these graphs shows the thermoregulation mechanisms of my skin (i.e. increased blood flow) working to balance out the constant heat load from the panel.
So even with our initial rudimentary testing, a reasonable heat therapy intensity would be between 55 to 70 mW/cm^2 with LED Panels, and of course monitor the skin temperature and adjust the distance or intensity to stay within the theraputic range for the required exposure time (20+ minutes).
The Best Red Light Therapy is... Heat Therapy?
Influencers promoting high-intensity LED Panels have inadvertently declared that Radiant Heat Therapy is the best form of Red Light Therapy.
Many brands have already FDA-registered as the ILY code as heating lamps under the Class II medium-risk category. Conspicuously not registered as true Photobiomodulation devices that even the FDA defined as non-thermal.
https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfRL/rl.cfm?lid=712608&lpcd=ILY
A disclaimer on Joovv's website reads:
"*Joovv light therapy products are intended to provide topical heating for the purpose of elevating tissue temperature"
[Link]
https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfRL/rl.cfm?lid=735369&lpcd=ILY
A disclaimer on Mito Red Light's website reads:
"DISCLAIMER: Mito Red Light devices are Class II wellness devices aimed at affecting the body through topical heating"
This should be rather strange, as PBM and LLLT studies don't describe themselves as intentionally causing heating.
Literally the opposite, as the PBM and LLLT are strictly a non-thermal light therapy that is dosed by low intensities and delivering the proper amount of Energy (J) or Energy Density (J/cm^2).
Statements like "topical heating" and "elevating tissue temperature" are literally describing a Heat Therapy, not a Red Light Therapy.
They mostly instruct the consumer how to use them as a red light therapy device and dose based on Joules, but we think they don't provide adequate warnings and instructions to use them for what they are actually FDA-registered for - as a heat therapy.
Joovv actually provides some instructions on how to use their panels as a Topical Heating device:
"The topical heating treatment distance is ideal for treating symptomatic areas. 10-20 minute treatments at 1-2 inches from your device is optimal"
[Link]
As we accurately prophesied in our Distance blog, using high-intensity LED Panels too close turns them into a Heat Therapy. Joovv has finally accepted their FDA-registered status as a "true medical grade" heat lamp.
A similar instruction would be expected for all the other brands FDA-registered as heat lamps.
According to the world's leading fake reviewer, the Best Red Light Therapy devices aren't even red light therapy at all, they are Therapeutic Heating devices as registered with the FDA.
A cynical person would assume that these brands got registered this way as a convenient loophole to make meaningless marketing claims of being FDA-Registered for a different category of medical product than they are actually selling. But that would be incredibly misleading, and these brands have never given us any reason to doubt their integrity or authenticity.
As positive people, we have to assume these brands got FDA-Registered as Therapeutic Heating devices because they genuinely believe that their products are indeed Heat Lamps.
It is clear these brands and influencers have doubted the efficacy of true "cold" red light therapy. Perhaps as a silent admission that their non-contact Red Light Therapy devices were ineffective, many brands secretly started selling LED Heat Lamps instead. A LED Heat Lamp at least delivers a tangible feeling of warmth for instant gratification.
Regardless, if "experts" want to debate that LED Heat Lamp Therapy is better than true "cold" Red Light Therapy - then we are all for it. However, we at least think there should be more transparency and giving the consumer informed consent that they aren't getting a true "cold" LLLT/PBM device, they are getting a fancy heat lamp.
Benefits and Safety would actually be improved if LED Heat Lamps provided proper instructions on how to use them as a heat lamp as we detailed in this blog, and not being misled as a different medical category of LLLT/PBM that is non-thermal.
Conclusions:
High Intensity LED Panels reside in a perfect grey area of being not exactly PBM, not exactly LLLT, not exactly HILT, not exactly wIRA, and not exactly Passive Heat Therapy.
They are the Schrodinger's Box of delivering all of these therapies simultaneously for massive benefits, none of these therapies for inhibitory actions, or worse could overheat the skin for detrimental effects.
In these recent 2 blogs, we dared to open the box and collapse the superimposed state. Giving these products a name of LED Heat Lamps perhaps under new sciences like High Intensity Light Therapy (HILT) and PhotoThermalbiomodulation. This way the naming is properly indicative of expecting heat, whereas LLLT and PBM are clearly for light therapies that do not deliver significant heating.
In the first blog, we likened LED Heat Lamps to High Intensity Laser Therapy (HILT), with dosing based on Energy (Joules or J/cm^2). This could prove to be an effective way to dose high intensity LEDs, but there are massive differences between a large LED panel and a laser delivering extremely high intensity at a small spot size.
In the current blog we considered allowing LED Heat Lamps to deliver heat therapy akin to the sciences of wIRA and Passive Heat Therapy. Heat therapies require longer treatment times of 20-60 minutes to saturate the tissue with a therapeutic amount of heating, contrary to brands claiming higher intensities shorten the treatment times.
This would deliver an inhibitory amount of Red Light Therapy, but promote the heat therapy mechanisms to dominate. Skin temperature should be monitored by thermometer to keep the temperature increase in the therapeutic range of 38-41C for the duration of the treatment, with adjusting the intensity or distance if the heat becomes uncomfortable or outside the safe range.
Ironically, intensity measurements are not as relevant for LED Heat Lamps, as we don't need to calculate J/cm^2 anymore, and just monitor the tissue temperature with a cheap thermometer. So after years of lying about intensity anyway, the LED Heat Lamp brands have made intensity entirely irrelevant to dosing for their products that they specifically claim to "elevate tissue temperature" and provide "topical heating".
Indeed, there are very few true Red Light Therapy devices left on the market. Most of them have become glorified LED Heat Lamps. When brands and fake experts stop false advertising their LED Heat Lamps as Photobiomodulation devices, then it would actually vastly improve safety, effectiveness, and informed consent to the consumer.
Perhaps one day LED Heat Lamps will become their own area of medical science, and we are simply witnessing the advent of a new health device.
References:
[1]
Hoffmann G. Principles and working mechanisms of water-filtered infrared-A (wIRA) in relation to wound healing. GMS Krankenhhyg Interdiszip. 2007;2(2):Doc54. Published 2007 Dec 28.
[2]
Piazena, H.; Kelleher, D.K. Effects of Infrared-A Irradiation on Skin: Discrepancies in Published Data Highlight the Need for an Exact Consideration of Physical and Photobiological Laws and Appropriate Experimental Settings. Photochem. Photobiol. 2010, 86, 687–705.
[3]
Zein R, Selting W, Hamblin MR. Review of light parameters and photobiomodulation efficacy: dive into complexity. J Biomed Opt. 2018;23(12):1-17. doi:10.1117/1.JBO.23.12.120901
[4]
De Moor RJ, Verheyen J, Diachuk A, et al. Insight in the chemistry of laser-activated dental bleaching. ScientificWorldJournal. 2015;2015:650492. doi:10.1155/2015/650492
[5]
Pizzey, F. K., Smith, E. C., Ruediger, S. L., Keating, S. E., Askew, C. D., Coombes, J. S., & Bailey, T. G. (2021). The effect of heat therapy on blood pressure and peripheral vascular function: A systematic review and meta-analysis. Experimental Physiology, 106, 1317–1334.
[6]
Patrick Rodrigues, Gabriel S. Trajano, Lee Wharton, Geoffrey M. Minett,
Effects of passive heating intervention on muscle hypertrophy and neuromuscular function: A preliminary systematic review with meta-analysis,
Journal of Thermal Biology,
Volume 93,
2020,
102684,
ISSN 0306-4565,
https://doi.org/10.1016/j.jtherbio.2020.102684.
(https://www.sciencedirect.com/science/article/pii/S0306456520304563)
[7]
Upper-Limb High-Intensity Interval Training or Passive Heat Therapy to Optimize Cardiorespiratory Fitness Prior to Total Hip or Knee Arthroplasty: A Randomized Controlled Trial
Brendon H. Roxburgh, Holly A. Campbell, James D. Cotter, Ulla Reymann, Michael J. A. Williams, David Gwynne-Jones, Kate N. Thomas
First published: 20 September 2023
https://doi.org/10.1002/acr.25238
[8]
Rivas F. In this Issue: Inflammation. Cell. 2010 Mar 19;140(6):755,757. PMID: 20361418.
[9]
Geddes L. The fever paradox. New Sci. 2020;246(3277):39-41. doi:10.1016/S0262-4079(20)30731-4
[10]
Roxburgh BH, Campbell HA, Cotter JD, et al. Acute and adaptive cardiovascular and metabolic effects of passive heat therapy or high-intensity interval training in patients with severe lower-limb osteoarthritis. Physiol Rep. 2023;11(11):e15699. doi:10.14814/phy2.15699
[11]
Durmuş, Hüseyin & Gün, Neslişah & Karaböce, Baki & Seyidov, Mirhasan. (2021). Investigation of temperature effects of a low-level laser source within the muscle phantom. International Journal of Advances in Applied Sciences. 10. 373. 10.11591/ijaas.v10.i4.pp373-377.
[12]
Cronshaw M, Parker S, Grootveld M, Lynch E. Photothermal Effects of High-Energy Photobiomodulation Therapies: An In Vitro Investigation. Biomedicines. 2023;11(6):1634. Published 2023 Jun 4. doi:10.3390/biomedicines11061634
[13]
Brunt VE, Minson CT. Heat therapy: mechanistic underpinnings and applications to cardiovascular health. J Appl Physiol (1985). 2021;130(6):1684-1704. doi:10.1152/japplphysiol.00141.2020
[14]
Wang Y, Huang YY, Wang Y, Lyu P, Hamblin MR. Photobiomodulation of human adipose-derived stem cells using 810nm and 980nm lasers operates via different mechanisms of action. Biochim Biophys Acta Gen Subj. 2017 Feb;1861(2):441-449. doi: 10.1016/j.bbagen.2016.10.008. Epub 2016 Oct 15. PMID: 27751953; PMCID: PMC5195895.
[15]
Passive heat therapy in sedentary humans increases skeletal muscle capillarization and eNOS content but not mitochondrial density or GLUT4 content
… See all authors
23 Jun 2019https://doi.org/10.1152/ajpheart.00816.2018
[16]
Brosseau L, Yonge KA, Robinson V, et al. Thermotherapy for treatment of osteoarthritis. Cochrane Database Syst Rev. 2003;2003(4):CD004522. doi:10.1002/14651858.CD004522
[17]
Mercer JB, Nielsen SP, Hoffmann G. Improvement of wound healing by water-filtered infrared-A (wIRA) in patients with chronic venous stasis ulcers of the lower legs including evaluation using infrared thermography. Ger Med Sci. 2008;6:Doc11. Published 2008 Oct 21.
[18]
Piazena H, Kelleher DK. Effects of infrared-A irradiation on skin: discrepancies in published data highlight the need for an exact consideration of physical and photobiological laws and appropriate experimental settings. Photochem Photobiol. 2010 May-Jun;86(3):687-705. doi: 10.1111/j.1751-1097.2010.00729.x. Epub 2010 Apr 16. PMID: 20408985.
[19]