Avoid heat stroke: Quench your thirst and stave off dehydration
Summer Howatt-Nab, Athens NEWS Special Projects Contributor
June 6, 2005
Each year, more people in the United States die from extreme heat than from hurricanes, lightning, tornadoes, floods and earthquakes combined, according to the federal Centers for Disease Control and Prevention (CDC). As the weather accommodates more outdoor activities, the risk of dehydration and heat-related illness rises.
Dehydration occurs when a person loses more fluids than he or she takes in. On a hot summer day, an active person can become dehydrated in just 15 minutes, according to the CDC Web site. The body cools itself by allowing heat to evaporate from the body in the form of sweat. However, when the humidity is high, sweat will not evaporate as quickly, preventing the body from releasing heat quickly. "Drinking plenty of liquids -- especially in hot, humid weather -- will prevent weakness, cramps and dehydration," according to the CDC.
Ohio University alumnus Monty Hunter said hydration is key to his training for the Marine Corps physical fitness test, which is a pre-requisite for Officer Candidates School.
"Pre-hydration is essential to my exercise regimen," he said.
Nicole Hughes, fitness director at the Athens Community Center, agreed. "First of all, if you have any signs of dehydration before you start your workout, then you should rehydrate first," she said.
However, Hughes said she does not encourage pre-workout "hyper-hydration" because it could cause hyponatremia, which can occur when the body becomes over-saturated with water, causing too little sodium in the blood. Hughes said hyponatremia is a plausible result of athletes drinking too much water, as it can dilute their plasma sodium, but said moderate to light exercisers are not usually at risk of hyponatremia. Hughes recommends drinking two to three cups of water two to three hours before exercising and consuming smaller amounts during the workout.
"I think hydration is really important during exercise," said Hunter, who lifts weights five days a week at Ping Center. "For every 15 minutes of working out, I drink water."
The Gatorade Sports Science Institute (GSSI) recommends incorporating fluid breaks into your routine.
"It's important to drink on schedule and not just when you're thirsty," according to the GSSI. "One 'gulp' usually equals about one ounce. A good rule of thumb is to drink seven to 10 gulps every 15 minutes of exercise."
Although eight glasses of water is the popular daily recommendation, Hughes explained that there isn't one generally recommended amount, since everyone's body is different.
According to an article in Women's Health magazine, a person's daily requirement depends on diet, size and unique body chemistry.
The GSSI states that "sweat composition not only varies among individuals but also with time during exercise, and is further influenced by the state of acclimatization."
The body's reaction to the climate in which a person is exercising plays a role. "On a hot day, you should make sure that you are continually drinking water as you work out," Hughes said.
Though one may feel cool and water-logged after swimming for an extended period of time, the body still requires fluids to prevent dehydration. "If a person feels any symptoms of dehydration at all while exercising, then stop exercising and rehydrate as soon as possible," Hughes advised. Dehydration warning signs include dizziness, rapid breathing, and dry lips and tongue, she said. (See accompanying article for practical tips to prevent dehydration this summer.)
The CDC's dehydration prevention guidelines include an increase in fluids, regardless of the activity level. According to the GSSI, "When heat and humidity are high, even a sedentary lifestyle is accompanied by a large increase in the body's water turnover. During hot weather, you will need to drink more liquid than your thirst indicates."
A more accurate indicator, according to the GSSI, is sweat. "Drinking on a schedule based upon your sweat loss before, during and after exercise can help you stay properly hydrated so that you can feel and perform at your best." A sweat-rate equation can be found on Gatorade's Web site (www.gatorade.com) to calculate one's sweat loss and replenishing needs.
Dieting can sap a person's water reserves as well. The GSSI warns against diets that emphasize shedding "water weight" as a quick way to lose weight. Darlene Berryman, assistant professor of human and consumer sciences at OU, explained, "Your initial weight loss from a low-carbohydrate diet would be water and glycogen stores. This has very little to do with the type of weight people are trying to lose."
Research conducted by the GSSI shows that a small percent change in body weight is due to a loss of fluid from sweat and can place a big strain on one's body during exercise. Rapid weight loss is an indicator of fluid loss and not of desirable body-fat loss, according to the GSSI Web site, which provides a sweat-rate equation. "When you lose this type of weight, you're losing fluids your body needs to perform and function properly."
The GSSI also recommends checking the color of your urine to determine your hydration level: "If the color of your urine looks like the color of apple juice, that is a good indication that you are dehydrated. If the color of your urine looks more like the color of lemonade, that indicates you are doing a good job at staying hydrated."
Diuretics, or substances that tend to increase urination, can trigger dehydration, especially in hot climates. The National Academy of Sciences' Institute of Medicine, which advises the government about recommended levels of nutrients, concluded that all fluids -- soft drinks, caffeinated beverages and alcoholic drinks -- factor in to your daily water totals. However, beverages that contain caffeine, such as colas, coffee or tea, stimulate fluid loss and promote dehydration.
Fitness specialist Hughes advises people to avoid diuretics, such as caffeine and alcohol. "I suggest people stay away from alcohol due to the fact that it is a diuretic and will dehydrate you really quickly on a hot, humid day and could lead to heat stroke," she said.
Recognizing heat-related illness is the first step in preventing a potentially fatal condition. If left untreated, dehydration can lead to heat exhaustion or heat stroke, according to the CDC. Conditions related to risk include age (the elderly and young children), obesity, fever, dehydration, heart disease, mental illness, poor circulation, sunburn, prescription drug use and alcohol use. Hughes said drinking water before, during and after exercise helps regulate heart rate and body temperature.
"When someone becomes dehydrated, it could lead to heat stroke and heat exhaustion, so drinking water will help prevent the body from overheating," she said.
Heat stroke occurs when the body becomes unable to control its temperature; the body's temperature rises rapidly, the sweating mechanism fails, and the body is unable to cool down, according to the CDC. Body temperature may ris
Comments
Please log in to post a comment.
