Heat therapy

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Heat therapy

Heat therapy, also called thermotherapy, is the use of heat in therapy, such as for pain relief and health. It can take the form of a hot cloth, hot water bottle, ultrasound, heating pad, hydrocollator packs, whirlpool baths, cordless FIR heat therapy wraps, and others. It can be beneficial to those with arthritis and stiff muscles and injuries to the deep tissue of the skin. Heat may be an effective self-care treatment for conditions like rheumatoid arthritis.[1]

Heat therapy is most commonly used for rehabilitation purposes. The therapeutic effects of heat include increasing the extensibility of collagen tissues; decreasing joint stiffness; reducing pain; relieving muscle spasms; reducing inflammation, edema, and aids in the post acute phase of healing; and increasing blood flow. The increased blood flow to the affected area provides proteins, nutrients, and oxygen for better healing.[2] There is some evidence to suggest that heat therapy can also aid in the treatment of neurodegenerative diseases like Alzheimer's; as well as for cardiovascular benefits.[3][4][5]


Direct contact

Moist heat therapy has been believed to be more effective at warming tissues than dry heat, because water transfers heat more quickly than air. Frequent use of saunas has been linked to a lower risk of vascular disease.[6][7][8][9][10][4] Clinical studies do not support the popular belief that moist heat is more effective than dry heat. Moist heat results in the perception that the tissue is heated more deeply. In fact, recent studies indicate that vasodilation, the expansion of the blood capillaries (vessels) to allow more blood flow, is improved with dry heat therapy. Expansion of the blood capillaries is the primary objective of heat therapy. Heat therapy increases the effect on muscles, joints, and soft tissue. Heat is typically applied by placing a warming device on the relevant body part.

Newer breeds of heat therapy devices combine a carbon fiber heater with a cordless rechargeable lithium battery and are built into the specific body wrap (i.e., shoulder wrap or back wrap) for targeted heat therapy. Such devices can be used as alternatives to chemical or plugged-in heating pads, but have not been shown to improve the clinical benefit. All devices primarily provide heat to promote vasodilation.

Infrared radiation

Infrared radiation is a convenient system to heat parts of our body. It has the advantage over direct contact in that radiation can heat directly the area where the blood capillaries and neuron terminals are. When heat comes from a direct contact source it has to heat the external layer of the skin, and heat is transferred to the deeper layer by conduction. Since heat conduction needs a temperature gradient to proceed, and there is a maximum temperature that can be safely used (around 42 °C), this means lower temperature where warming is needed.

Infrared (IR for short) is the part of the electromagnetic radiation spectrum comprised between 0.78 μm and 1 mm wavelength. It is usually divided into three segments:

IR-A, from 0.78 to 1.4 μm.
IR-B, from 1.4 to 3 μm.
IR-C, from 3 μm to 1 mm.

IR radiation is more useful than the visible radiation for heating our body, because we absorb most of it, compared to a strong reflection of visible light. Penetration depth of infrared radiation in our skin is dependent of wavelength. IR-A is the most penetrating, and reaches some millimeters, IR-B penetrates into the dermis (about 1 mm), and IR-C is mostly absorbed in the external layer of the epidermis (stratum corneum).[11] For this reason the infrared lamps used for therapeutic purposes produce mainly IR-A radiation.

Mechanism of action, and indications[edit]

Heat creates higher tissue temperatures, which produces vasodilation that increases the supply of oxygen and nutrients and the elimination of carbon dioxide and metabolic waste.[12]

Heat therapy is useful for muscle spasms, myalgia, fibromyalgia, contracture, bursitis.[12]

Moist heat can be used on abscesses to help drain the abscess faster.[13] A study from 2005 showed heat therapy to be effective in treating leishmaniasis, a tropical parasitic skin infection.[14]

Heat therapy is also sometimes used in cancer treatment to augment the effect of chemotherapy or radiotherapy, but it is not enough to kill cancer cells on its own.[15]

Heat therapy is contraindicated in case of acute injury and bleeding disorders (because of vasodilation), tissues with a severe lack of sensitivity, scars[12] and in tissues with inadequate vascular supply (because of increased metabolic rate and demand which a tissue with poor blood supply may fail to meet resulting in ischemia).[16]

The use of Heat therapy for deep-seated tissue can be treated with shortwave, microwave, and ultrasonic waves. This produces a high temperature that penetrates deeper. Shortwave produces a 27 MHz current, microwaves use 915 and 2456 MHz, and ultrasound is an acoustic vibration of 1 MHz. The way ultrasonic waves work is they selectively superimpose the incoming wave and increase the energy for absorption, and the significant part of the longitudinal compression gets converted into shear waves. When they are rapidly absorbed, the interface between soft tissue and bone is selectively heated.[17]

For headaches[edit]

Heat therapy can be used for the treatment of headaches and migraines.[citation needed] Many people with chronic headaches also experience tight muscles in their neck and upper back. The application of constant heat to the back/upper back area can help to release the tension associated with headache pain. In order to achieve heat therapy for headaches, many use microwaveable pads[citation needed] which can often overheat, potentially leading to injury, and lose their heat after a few minutes. Some new products use heated water, running through pads, to maintain a constant temperature, allowing people with headaches to use hands-free heat therapy in the treatment of their headache pain.[citation needed] However no substantial scientific evidence exist for many of these claims.

Therapeutic Benefits[edit]

Thermotherapy increase the extensibility of collagen tissues. Using heat, it can relieve the stiffness in joints in different cases. Shortwave and Microwave heat application may reduce muscle spasms, and selective heating with microwaves can accelerate absorption of hematomas. This will, in turn, allow the stiff muscle to stretch. Ultrasounds are not absorbed significantly in homogenous muscle. Heat therapy using hyperthermia has been used to treat cancer in combination with ionizing radiation.[18]

See also[edit]


  1. ^ Thermotherapy for treating rheumatoid arthritis, from Cochrane Library
  2. ^ Prentice, William E. Arnheim's Principles of Athletic Training: a Competency Based Approach. New York. McGraw-Hill. 2008.
  3. ^ Gravel, Hugo; Behzadi, Parya; Cardinal, Sarah; Barry, Hadiatou; Neagoe, Paul-Eduard; Juneau, Martin; Nigam, Anil; Sirois, Martin G.; Gagnon, Daniel (2021-03-01). "Acute Vascular Benefits of Finnish Sauna Bathing in Patients With Stable Coronary Artery Disease". Canadian Journal of Cardiology. 37 (3): 493–499. doi:10.1016/j.cjca.2020.06.017.
  4. ^ a b Shepley, Brooke R.; Ainslie, Philip N.; Hoiland, Ryan L.; Donnelly, Joseph; Sekhon, Mypinder S.; Zetterberg, Henrik; Blennow, Kaj; Bain, Anthony R. (2021-03-01). "Negligible influence of moderate to severe hyperthermia on blood-brain barrier permeability and neuronal parenchymal integrity in healthy men". Journal of Applied Physiology. 130 (3): 792–800. doi:10.1152/japplphysiol.00645.2020. ISSN 8750-7587.
  5. ^ Von Schulze, Alex T.; Deng, Fengyan; Morris, Jill K.; Geiger, Paige C. (2020-12-01). "Heat therapy: possible benefits for cognitive function and the aging brain". Journal of Applied Physiology. 129 (6): 1468–1476. doi:10.1152/japplphysiol.00168.2020. ISSN 8750-7587.
  6. ^ Brunt, Vienna E.; Howard, Matthew J.; Francisco, Michael A.; Ely, Brett R.; Minson, Christopher T. (2016-09-15). "Passive heat therapy improves endothelial function, arterial stiffness and blood pressure in sedentary humans: Passive heat therapy and vascular function". The Journal of Physiology. 594 (18): 5329–5342. doi:10.1113/JP272453.
  7. ^ Laukkanen, Jari A.; Laukkanen, Tanjaniina; Khan, Hassan; Babar, Maira; Kunutsor, Setor K. (2018-04-01). "Combined Effect of Sauna Bathing and Cardiorespiratory Fitness on the Risk of Sudden Cardiac Deaths in Caucasian Men: A Long-term Prospective Cohort Study". Progress in Cardiovascular Diseases. 60 (6): 635–641. doi:10.1016/j.pcad.2018.03.005.
  8. ^ Laukkanen, Tanjaniina; Kunutsor, Setor K.; Zaccardi, Francesco; Lee, Earric; Willeit, Peter; Khan, Hassan; Laukkanen, Jari A. (2017-12-21). "Acute effects of sauna bathing on cardiovascular function". Journal of Human Hypertension. 32 (2): 129–138. doi:10.1038/s41371-017-0008-z. ISSN 0950-9240.
  9. ^ Laukkanen, Tanjaniina; Kunutsor, Setor; Kauhanen, Jussi; Laukkanen, Jari Antero (2017-03-01). "Sauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish men". Age and Ageing. 46 (2): 245–249. doi:10.1093/ageing/afw212. ISSN 0002-0729.
  10. ^ Laukkanen, Tanjaniina; Khan, Hassan; Zaccardi, Francesco; Laukkanen, Jari A. (2015-04-01). "Association Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality Events". JAMA Internal Medicine. 175 (4): 542. doi:10.1001/jamainternmed.2014.8187. ISSN 2168-6106.
  11. ^ The International Commission on Non-Ionizing Radiation Protection (ICNIRP). "ICNIRP Statement on Far Infrared Radiation Protection" (PDF). Health Physics Society. Archived from the original (PDF) on 2011-07-19. Retrieved 2011-02-12.
  12. ^ a b c Raj, P. Pritvi, Practical Management of Pain. Mosby. 2.000. ISBN 978-0-8151-2569-3.
  13. ^ "Skin abscess: MedlinePlus Medical Encyclopedia". medlineplus.gov. Retrieved 2016-08-03.
  14. ^ Reithinger, R.; Mohsen, M.; Wahid, M.; Bismullah, M.; Quinnell, R. J.; Davies, C. R.; Kolaczinski, J.; David, J. R. (2005-04-15). "Efficacy of Thermotherapy to Treat Cutaneous Leishmaniasis Caused by Leishmania tropica in Kabul, Afghanistan: A Randomized, Controlled Trial". Clinical Infectious Diseases. 40 (8): 1148–1155. doi:10.1086/428736. ISSN 1058-4838. PMID 15791515.
  15. ^ "Hyperthermia to Treat Cancer". www.cancer.org. Retrieved 2016-08-03.
  16. ^ West, Sterling (2014-10-23). Rheumatology Secrets. Elsevier Health Sciences. ISBN 9780323172875.
  17. ^ Lehmann, Justus F. "Thermotherapy." AccessScience. McGraw-Hill Education, 2014. Web. 2 May 2015.
  18. ^ Lehmann, Justus F. "Thermotherapy." AccessScience. McGraw-Hill Education, 2014. Web. 3 May 2015.
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