Health Advice Agnes Oblas

I was in the gym sweating up a storm. As the salty droplets fell from the tip of my nose, from my armpits and even from my knees I wondered, “Why do we sweat when we exercise?” Why do we sweat more in the heat of summer or when we have fevers? Why do we sweat more if we become nervous, angry or embarrassed? The quick answer, of course, is that it is the body’s way of cooling itself. I knew that, and you probably do, too. But why and how does the body know it needs to sweat to cool itself down?

We are born with 2 to 4 million sweat glands that are mostly located under the arms, on the soles of the feet, and on the palms of the hands. The function of these glands is controlled by a part of the nervous system that is not under conscious control: the Autonomic Nervous System. The purpose of sweating is to maintain the core body temperature normal at about 98.6 degrees Fahrenheit.

When the food you eat goes through the digestive process, the metabolic “burning” of the calories ingested results in heat production. Another source of heat production is simply being outside in the heat of the day, (think of a chicken or turkey sitting inside a hot oven; it gets hot and cooked, right?). Heat is also produced when you are sick and the immune system kicks into high gear to fight the infection or illness: a fever results. Even though these are normal processes, a prolonged elevation of the internal core temperature is not conducive to healthy functioning of other body systems. So Mother Nature developed sweating as the body’s own evaporative cooling system.

The Autonomic Nervous System (the hypothalamus gland within the brain specifically) can detect when the internal core temperature is elevated. It then causes the blood vessels nearest the surface of the skin to dilate (thus, we get flushed). The dilated blood vessels then loose some fluid, which is then released through the pores of the skin and via sweat glands Salt is released along with this fluid, which is why sweat tastes salty and why we need to replenish salt along with water when we sweat excessively. The sweat produced may be acted upon by bacteria, causing a noticeable odor. Nervousness and anxiety also signals the hypothalamus to initiate sweat production. Even in normal or cool ambient temperatures, the body maintains its core temperature with this evaporative cooling system. This is why it is so important to replenish this fluid loss with drinking water.

Without sweating we would cook ourselves from the inside out. Heat stroke or heat exhaustion is very real and either is a dangerous situation, especially here in Phoenix. In extreme heat or with vigorous physical activity under the sun, the body may not be able to dissipate the heat fast enough and the core temperature may exceed 104 degrees. A dehydrated person may not be able to sweat fast enough to dissipate the internal heat. So drink that water.

Heat exhaustion can progress to heat stroke, a life threatening medical emergency, quickly. Know these symptoms: fatigue, weakness, muscle cramping, nausea with or without vomiting, headache, dizziness, strange behavior or even hallucinations, the absence of sweating, severe flushing and a rapid pulse. First aid for heat exhaustion or heat stroke involves calling 911 and proceeding to rapid cooling of the body: by getting out of the heat into a shaded area or air-conditioning, applying cold wet sheets or towels or just dousing the body with cold water, getting the cold and wet evaporated by a fan or manually fanning with anything handy, and of course drinking water, water, water.

• Agnes Oblas is an adult nurse practitioner with a private practice and residence in Ahwatukee Foothills. For questions, or if there is a topic you would like her to address, call (602) 405-6320, email or visit

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