Heat therapy, also called thermotherapy, is the use of

heat In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is ...

therapy A therapy or medical treatment (often abbreviated tx, Tx, or Tx) is the attempted remediation of a health problem, usually following a medical diagnosis. As a rule, each therapy has indications and contraindications. There are many differe ...

, such as for

pain relief Pain management is an aspect of medicine and health care involving relief of pain (pain relief, analgesia, pain control) in various dimensions, from acute and simple to chronic and challenging. Most physicians and other health professional ...

and health. It can take the form of a hot cloth, hot water bottle,

ultrasound Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies ...

, heating pad, hydrocollator packs, whirlpool baths, cordless FIR heat therapy wraps, and others. It can be beneficial to those with

arthritis Arthritis is a term often used to mean any disorder that affects joints. Symptoms generally include joint pain and stiffness. Other symptoms may include redness, warmth, swelling, and decreased range of motion of the affected joints. In som ...

and stiff

muscle Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of mus ...

s and injuries to the deep tissue of the skin. Heat may be an effective self-care treatment for conditions like

rheumatoid arthritis Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and hands are inv ...

. 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 Edema, also spelled oedema, and also known as fluid retention, dropsy, hydropsy and swelling, is the build-up of fluid in the body's tissue. Most commonly, the legs or arms are affected. Symptoms may include skin which feels tight, the area ma ...

, 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. 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.

Application

;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. 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 Conduction is the process by which heat is transferred from the hotter end to the colder end of an object. The ability of the object to conduct heat is known as its ''thermal conductivity'', and is denoted . Heat spontaneously flows along a te ...

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 Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of Light, visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from ...

(IR for short) is the part of the

electromagnetic radiation In physics, electromagnetic radiation (EMR) consists of waves of the electromagnetic (EM) field, which propagate through space and carry momentum and electromagnetic radiant energy. It includes radio waves, microwaves, infrared, (visib ...

spectrum comprised between 0.78 μm and 1 mm

wavelength In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tr ...

. 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). For this reason the

infrared lamp Infrared lamps are electrical devices which emit infrared radiation. Infrared lamps are commonly used in radiant heating for industrial processes and building heating. Infrared LEDs are used for communication over optical fibers and in remote c ...

s used for therapeutic purposes produce mainly IR-A radiation.

Mechanism of action, and indications

Heat creates higher tissue temperatures, which produces

vasodilation Vasodilation is the widening of blood vessels. It results from relaxation of smooth muscle cells within the vessel walls, in particular in the large veins, large arteries, and smaller arterioles. The process is the opposite of vasoconstrictio ...

that increases the supply of oxygen and nutrients and the elimination of carbon dioxide and metabolic waste.Raj, P. Pritvi, Practical Management of Pain. Mosby. 2.000. . Heat therapy is useful for

muscle spasms A spasm is a sudden involuntary contraction of a muscle, a group of muscles, or a hollow organ such as the bladder. A spasmodic muscle contraction may be caused by many medical conditions, including dystonia. Most commonly, it is a muscle c ...

myalgia Myalgia (also called muscle pain and muscle ache in layman's terms) is the medical term for muscle pain. Myalgia is a symptom of many diseases. The most common cause of acute myalgia is the overuse of a muscle or group of muscles; another li ...

fibromyalgia Fibromyalgia (FM) is a medical condition defined by the presence of chronic widespread pain, fatigue, waking unrefreshed, cognitive symptoms, lower abdominal pain or cramps, and depression. Other symptoms include insomnia and a general hyp ...

contracture In pathology, a contracture is a permanent shortening of a muscle or joint. It is usually in response to prolonged hypertonic spasticity in a concentrated muscle area, such as is seen in the tightest muscles of people with conditions like sp ...

bursitis Bursitis is the inflammation of one or more bursae (fluid filled sacs) of synovial fluid in the body. They are lined with a synovial membrane that secretes a lubricating synovial fluid. There are more than 150 bursae in the human body. The bursae ...

. Moist heat can be used on abscesses to help drain the abscess faster. A study from 2005 showed heat therapy to be effective in treating leishmaniasis, a tropical parasitic skin infection. 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. Heat therapy is contraindicated in case of

acute injury Major trauma is any injury that has the potential to cause prolonged disability or death. There are many causes of major trauma, blunt and penetrating, including falls, motor vehicle collisions, stabbing wounds, and gunshot wounds. Depending ...

and bleeding disorders (because of vasodilation), tissues with a severe lack of sensitivity, scars and in tissues with inadequate

vascular The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away f ...

supply (because of increased metabolic rate and demand which a tissue with poor blood supply may fail to meet resulting in ischemia). 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.

For headaches

Heat therapy can be used for the treatment of

headache Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches. Headaches can occur as a result ...

s and

migraine Migraine (, ) is a common neurological disorder characterized by recurrent headaches. Typically, the associated headache affects one side of the head, is pulsating in nature, may be moderate to severe in intensity, and could last from a few hou ...

s. 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 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. However no substantial scientific evidence exist for many of these claims.

Therapeutic Benefits

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.Lehmann, Justus F. "Thermotherapy." AccessScience. McGraw-Hill Education, 2014. Web. 3 May 2015.

References

* Israel, Beth. "Pain". Stoppain.org. 2005. Date Assessed: 28 April 2009.

* "Deep Heat Treatment.." CRS - Adult Health Advisor (Jan. 2009): 1-1. Health Source - Consumer Edition. EBSCO. Kent Library, Cape Girardeau, MO. 30 Apr. 200

* Scott F. Nadler, DO, FACSM, Kurt Weingand, PhD, DVM, and Roger J. Kruse, MD. "The Physiologic Basis and Clinical Applications of Cryotherapy and Thermotherapy for the Pain Practitioner". Pain Physician. 7 (2004): 395–399. {{DEFAULTSORT:Heat Therapy Pain management Athletic training

Application

Mechanism of action, and indications

For headaches

Therapeutic Benefits

See also

References