Insider Info: Feel the Heat

  • Department
Young boy drinking from hose

Drink Up

Know what fluids to drink, and how much, during outdoor activities.

Over half of your body is water. It’s a critical component of good health, tied to all your body’s functions. If you sweat out 3% of your body weight during an afternoon in the sun, you’re dehydrated. (That’s five pounds of perspiration if you weigh 150 pounds.) You crave fluids, feel tired, and don’t perform at your best. Lose more than that, and you’re on your way to becoming critically dehydrated. Regardless of your size, a 10% loss of your total body water causes a noticeable decline in physical and mental capabilities. A 15% loss or more and you can die.

The more physically fit you are, the more efficient your body becomes at cooling itself and thus lowering your risk of overheating. Fit folks begin to sweat sooner during exercise and at a higher rate, if they stay hydrated. The more you sweat, the more fluids you need, regardless of your fitness level.

According to the National Institutes of Health, the average person on an average day needs to take in about three quarts of water. But on a hot day, especially if you are exerting yourself, you need a lot more than that. The elderly, babies, and people taking antihistamines, blood pressure medication, diuretics, laxatives, or chemotherapy are at greater risk of dehydration.

Common symptoms of dehydration include:

  • Thirst
  • Infrequent and dark-colored urine
  • Muscle cramps
  • Lack of perspiration even though the air temperature is hot
  • Fatigue, unusual sleepiness
  • Dizziness, fainting
  • Confusion
  • Fever

For an average-size person to prevent dehydration, the American College of Sports Medicine recommends drinking 16-20 ounces of fluid one to two hours before an outdoor activity, another 6-12 ounces every 15 minutes you’re out there, and another 16-24 ounces after you’ve finished.

Electrolytes are substances like sodium, potassium, calcium, bicarbonate, magnesium, chloride, and phosphate that conduct electricity when mixed with water. Muscles need electrolytes to contract, and nerves use electrolytes to carry electrical impulses to other cells.

Some drinks keep you hydrated and help you rehydrate better than others. Water works for low- to moderate-intensity outdoor activities, such as walking for an hour or less. For high-intensity and/or longer duration activities, a sports drink is better. Excessive perspiration causes the loss of electrolytes, which need to be replaced, preferably by sipping a sports drink or a 50/50 combination of fruit juice and water mixed with some salt.

Alcoholic beverages and caffeinated drinks, such as coffee, tea, and cola, are mild diuretics that draw water from the body. They are okay in moderate amounts if you’re not already dehydrated.

You can also get fluids from what you eat, especially fruits and vegetables. So grab a slice of watermelon or a handful of cherry tomatoes to stay hydrated during, and to help rehydrate after, an outdoor activity!

Cool Off

Prevent muscle cramps or heat stroke on a hot day.

As the temperature climbs on a summer day, so does the chance of heat-related illnesses. Everyone is susceptible. What's more, heat cramps can quickly turn into more serious heat exhaustion, or worse, heat stroke, if not treated correctly.

Heat-related illnesses happen when you can no longer maintain a normal body temperature of 97.7 to 99.5°F. Your core temperature increases, which could lead to organ failure and death if it is not quickly corrected.

Women have more sweat glands – but sweat less – than men.

Evaporation of sweat is the body's chief way of dissipating heat. Humidity is a big factor in how well this works. Drier air lifts more water off your skin faster. However, when humidity is above 75%, evaporation slows. As humidity nears 100%, evaporation nearly ceases. That's why a 90° day in Arizona feels more comfortable than a 90° day in Georgia. Wind lifts perspiration off skin, providing a cooling effect. Days that are hot, humid, and still (no breeze) are the most dangerous.

If you need to be outdoors on a hot day, Virginia Commonwealth University School of Medicine offers these tips on how to prevent heat-related illnesses:

  1. Watch the heat index, which considers temperature and humidity. If it's 80 to 90°F, be careful. If it's over 90°F, save strenuous outdoor activities for another day.
  2. Stay hydrated before, during, and after you go outdoors.
  3. Exercise early in the morning or late in the evening and shorten the duration.
  4. Take frequent breaks in the shake, preferably by a fan.

Summertime is outdoor time. No need to stay inside on a hot day – just work and play wisely!

The American Heart Association recommends the following actions if you see someone who has overheated.

Heat Cramps

Symptoms: Muscle spasms, often in the calves, arms, stomach, and/or back.

First Aid: Rest. Cool off in the shade or in an air-conditioned space. Sip fluids containing sugar and electrolytes, or water if a sports drink or juice is not available. Wrap a bag of ice in a towel and apply it to the cramping area for 20 minutes.

Heat Exhaustion

Symptoms: Nausea, dizziness, vomiting, muscle cramps, feeling faint or fatigued, heavy sweating, pale clammy skin.

First Aid: Lie down in the shade or in an air-conditioned space. Remove excess clothing. Spray with cool water or place cool, damp towels on the neck, armpits and groin. If the person can drink, sip fluids with sugar and electrolytes in them or water if a sports drink or juice is not available.

Heat Stroke

Symptoms: The same as heat exhaustion, plus confusion, gasping for breath, high heart and respiratory rates, elevated body temperature, hot, red, dry skin, unconsciousness, seizures.

First Aid: Every minute counts! Call 911. Immerse all but the person’s head in cool water. If the person begins to recover, stop cooling to prevent hypothermia. (The body’s ability to regulate its temperature may be compromised.) Give CPR if the person is unresponsive.

Writer/photographer Lisa Ballard is an Ike from Red Lodge, Montana. She is one of the top-ranked master ski racers in the world. To stay in shape during the summer, she's constantly hiking, running, biking, paddling... and sweating.