Preventing Dehydration and Heat Stroke

No matter how many times people hear messages about remaining properly hydrated in the hot weather, it’s easy to forget that heat, sun and even minor outdoor activity can make dangerous companions.

Proper fluid levels are important for ensuring a good flow of oxygen and red blood cells to our muscles and organs. During exercise and activity, we lose valuable nutrients and minerals. These include sodium, magnesium and potassium, which help keep our muscles working properly, reduce fatigue and prevent dehydration.

Under normal conditions, we all lose body water daily through sweat, tears, breathing and going to the bathroom. This water is normally replaced by drinking fluids and eating foods that contain water. When a person becomes sick and experiences fever, diarrhea or vomiting, dehydration occurs. It also happens if someone is overexposed to the sun and heat and not drinking enough water. Additionally, it can be caused by certain medicines, such as diuretics, which deplete body fluids and electrolytes.

Even without hot weather, our bodies create a large amount of internal heat. We normally cool ourselves by sweating and radiating heat through the skin. However, in certain circumstances, such as extreme heat, high humidity, or vigorous activity in the hot sun, this cooling system may begin to fail. This allows heat to build up to dangerous levels; it is exacerbated when we don’t replace those fluids, and compounded by the loss of essential body salts. If a person becomes dehydrated and cannot sweat enough to cool his or her body, his or her internal temperature may rise to dangerously high levels. This causes heat stroke, which can be life threatening.

The following are the most common symptoms of dehydration and heat stroke:

  • Thirst
  • Less-frequent urination
  • Dry skin
  • Fatigue
  • Light-headedness or dizziness
  • Confusion
  • Dry mouth and mucous membranes
  • Increased heart rate and breathing

In children, additional symptoms may include dry mouth and tongue, no tears when crying, listlessness, irritability and hallucinations.

In cases of mild dehydration, simple rehydration is recommended by drinking fluids. Many sports drinks effectively restore body fluids, electrolytes, and salt balance. For moderate dehydration, intravenous (IV) fluids may be needed. If caught early enough, simple rehydration may be effective. Cases of serious dehydration should be treated as a medical emergency, and hospitalization, along with intravenous fluids, is necessary.

How Much Should You Drink?

The rule of thumb should be to drink plenty of liquids before, during and after each activity.

A good guideline to use when preparing for an outdoor workout is to drink about two cups of fluid two hours before the activity. That helps make sure we are well-hydrated before we even go outdoors. Then, during the activity, we should drink four to six ounces every 15 to 20 minutes to keep our muscles well-hydrated. If planning an hour-long walk or gym workout, take a water bottle with about 16 ounces (two cups). Then, after exercise, drink again.

Fluids are vital to help our muscles function throughout our activity, but so is our blood sugar. Eat a light meal or snack of at least 100 calories about an hour or so before an activity. The nutrients from the snack will help keep hunger from interfering. The best snacks combine healthy carbohydrates, protein, and a small amount of fat. Fruit, yogurt, nuts, and granola bars are all good examples.

For most outdoor activities, regular tap or bottled water does the trick. If activity lasts an hour or more, either fruit juice diluted with water or a sports drink will provide carbohydrates for energy, plus minerals to replace electrolytes lost from sweating.

Sports drinks like Gatorade, Powerade, and All Sport can provide a needed energy boost during activity. They are designed to rapidly replace fluids and to increase the sugar (glucose) circulating in our blood. However, read the label to determine which sports drinks are most effective. Ideally, it will provide around 14 grams of carbohydrates, 28 mg of potassium, and 100 mg of sodium per eight-ounce serving. The drink’s carbohydrates should come from glucose, sucrose, and/or fructose, rather than from processed sugar or corn syrup. These are more easily and quickly absorbed. It shouldn’t be carbonated, as the bubbles can lead to an upset stomach.

“Fitness waters” are lightly flavored and have added vitamins and minerals. The additional nutrients are meant to supplement a healthy diet — not replace losses from exercise.

Fitness waters fall somewhere between the sports drinks and plain water in terms of being effective hydrators. They contain fewer calories and electrolytes but offer more taste than plain water. Whatever helps keep you hydrated is worth considering — as long as you keep drinking!


Be sure to check out the CBIA Healthy Connections wellness program at your company’s next renewal. It’s free as part of your participation in CBIA Health Connections!