The purpose of heat therapy is generally to rehabilitate chronic injuries and late-stage acute injures. Chronic injuries are acquired from overuse and usually cause a long-term negative change in the body. Acute injuries are those that unexpectedly and suddenly happen and, though severe in nature, usually last only a short time. Late-stage acute injuries are those that have that have been present for 72 hours or longer. They may have been treated with cold therapy (such as with ice packs).
The application of heat to an injured part of the body helps to:
For instance, discomfort in the lower back due to strain or injury can be reduced by heat therapy. The application of a temperature higher than body temperature to the lower back expands the blood vessels of the muscles surrounding the lower spine. This in turn increases the flow of oxygen and nutrients into those muscles, which helps in the healing process. In addition, heat on a sore lower back helps to stimulate the sensory receptors in the skin covering the back, which decreases the processing of pain signals within the brain and appreciably lowers pains levels. The application of heat to the lower back also helps to stretch soft tissues around the spine, thus reducing stiffness and increasing flexibility, which provides for an overall increase in comfort.
In one form or another, the application of heat to inflamed, sore, painful, or swollen body parts has been performed from mankind's earliest days. Over the years, doctors found that such treatment helps in the healing process and reduces the symptoms of an injury. As more was learned about the application of heat to injuries, the concept of heat therapy was developed by the medical community.
When an injury occurs, heat therapy is effective at spurring the healing process because the application of a higher temperature (warmth) to the affected area produces an increase in the supply of amino acids, nutrients, and oxygen, and a decrease in carbon dioxide and metabolic waste.
Two primary types of heat therapy are dry and moist. Dry heat, as the name suggests, comes about from the application of heat without moisture. Electric heating pads and saunas produce dry heat therapy, which draws moisture from the body. Moist heat, on the other hand, involves the application of heat with moisture via damp towels, heating packs, and hot baths. Moist heat devices allow the heat to penetrate more deeply into muscles.
Heat therapy can be applied using several different methods:
Heat therapy should be used with caution in some cases. It is important to always place an insulating material between a directly applied heat source and the skin to avoid burning or overheating of the skin. The use of infrared radiation should be limited to a maximum temperature of about 107°F (42°C) to avoid damage to the skin
Heat therapy should not be applied to anyone:
Heat therapy should also not be applied:
The application of heat increases the flow of blood at the contact point because heat is a vasodilator—it widens the blood vessels. Therefore, heat therapy would be inappropriate in the case of a disorder in which blood does not easily clot because it could make the condition worse. Thus, heat therapy should not be applied when a person has such medical conditions such as dermatitis, deep vein thrombosis, diabetes, or peripheral vascular disease.
Heat therapy is most effective when heat is applied at a constant level and is warm to the skin, not hot. When the temperature is hot, there is a greater chance of burning the skin. Extremely hot temperatures are not more effective than lesser ones in reducing the symptoms of an injury or in increasing the healing time.
Generally, the longer that heat is applied, the better. Application time is based on the type and magnitude of the injury. For instance, minor injuries should be treated over short periods, from 15 to 30 minutes, that can be repeated as desired. For more serious injuries, heat should be applied for longer amounts of time—30 minutes to 2 hours or longer.
If the application of heat therapy does not improve symptoms, or symptoms become worse, the individual should seek medical care.
Heat therapy can provide relief from injuries to the lower back and from various problems with muscles and joints caused by a variety of physical activities.
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American Association of Orthopaedic Surgeons, 9400 W. Higgins Rd., Rosemont, IL, 60018, (847) 823-7186, Fax: (847) 823-8125, http://www.aaos.org/ .
American College of Sports Medicine (ACSM), 401 W. Michigan St., Indianapolis, IN, 46202-3233, (317) 6379200, Fax: (317) 634-7817, http://www.acsm.org .
American Pain Society, 8735 W. Higgins Rd., Ste. 300, Chicago, IL, 60631, (847) 375-4715, info@american painsociety.org, http://americanpainsociety.org .
William A. Atkins, BB, BS, MBA