What is sweating?

Structure and Functions

Sweat glands are exocrine glands, which secrete products that are passed outside the body. There are two major types. Eccrine sweat glands excrete sweat that contains water and several salts. They are located in the skin throughout the body but are found in greater concentrations in the palms of the hands, soles of the feet, and forehead. Apocrine sweat glands excrete sweat that contains water and fatty substances. They are primarily found in the armpits and genital area. When bacteria break down the fatty materials, distinctive sweat odors develop.

The primary function of sweating in humans is to regulate body temperature. When the body temperature rises, the blood flow to the skin increases by opening more capillaries in the skin. Since blood can hold heat and circulates throughout the body, the blood can transport heat from the inner core of the body, where the temperatures are higher and the heat is more insulated, to the surface, where the heat is less insulated. In the skin, the warm blood will transfer the heat to the surface, where sweat glands release sweat. When the sweat evaporates, changing its physical state from a liquid to a gas, significant amounts of heat are removed from the body.

Disorders and Diseases

Sweating is a normal process that is important for the temperature regulation (thermoregulation) of the body, but complications can arise. The most critical result of excess sweating is dehydration. The biggest risk for dehydration occurs when people exercise in hot, humid environments. Therefore, it is important to drink plenty of water. Additionally, when sweating a lot for a period of days, additional salts may be beneficial. Most sports drinks supply adequate salts. In extreme conditions, the excess loss of water in sweat can lead to heatstroke and death. When the body loses too much water, the sweating mechanism shuts down. Without the advantage of sweat evaporation to cool the body, the temperature will continue to rise until death ensues. Anyone who has symptoms of heat stress—such as a body temperature over 105 degrees Fahrenheit, cessation of sweating, or altered mental state—should get immediate medical attention. The intravenous administration of fluids by medical personnel will rehydrate the body quickly.

A less concerning disorder of sweating is hyperhidrosis. People with this condition sweat frequently and in excess of what is required to regulate body temperature. About 1 percent of people have this condition; it is often linked to obesity. There are numerous treatments but no cure. Typical treatments include surgery, medications, biofeedback, relaxation, hypnosis, and weight loss.

In July 2013, the American Heart Association published a study showing that sweating through excercise could reduce an individual's risk of stroke.

Bibliography

"Breaking a Sweat While Excercising Regularly May Help Reduce Strong Risk." American Heart Association. July 22, 2013.

Brooks, George A., Thomas D. Fahey, and Kenneth M. Baldwin. Exercise Physiology: Human Bioenergetics and Its Applications. 4th ed. Boston: McGraw-Hill, 2007.

"Hyperhidrosis (Excessive Sweating)." Mayo Clinic. September 21, 2012.

McArdle, William, Frank I. Natch, and Victor L. Natch. Exercise Physiology: Energy, Nutrition, and Human Performance. 7th ed. Boston: Lippincott Williams & Wilkins, 2010.

"NIH-Funded Study Suggests That Moving More May Lower Stroke Risk." National Institutes of Health. July 18, 2013.

Powers, Scott K., and Edward T. Howley. Exercise Physiology: Theory and Application to Fitness and Performance. 7th ed. New York: McGraw-Hill, 2009.