Heat and Hydration

The weather forecast is 90 degrees for the next 4-5 days in Michigan. In many areas of the country this heat is felt often. For my sister living in California's middle desert, it's a dry heat. For my sister in Richmond, it's both heat and humidity. Wherever you live, when heat waves hit, it's important to be cautious and drink more fluids.

Understanding the effects of heat and adequate body water is essential to minimize the change of heat injury. Young children and older adults are more at risk for dehydration and need to be monitored carefully.

Many people think that as long as they don't feel thirsty, they are getting plenty of fluids. Unfortunately, thirst is not the best indicator of dehydration. Doctors suggest a better way to evaluate hydration is to monitor urine color. Darker gold or amber urine signals dehydration (though some vitamin supplements may also temporarily darken urine). Clear or pale straw color indicates adequate fluids. Go for clear.

  • Heat Exhaustion can produce mild to moderate dehydration. Symptoms include:
    • Dry, sticky mouth and increased thirst
    • Flushed skin & rise in body temperature
    • Increased pulse & breathing rate or labored breathing
    • Dry skin
    • Paleness
    • Muscle cramps
    • Reduced urination
    • Headache
    • Nausea
    • Constipation
    • Dizziness
    • Weakness
    • Results in loss of fluid from blood which makes the heart work harder.
  • Heat stroke causes severe dehydration and is a life threatening medical emergency. The body has lost it's ability to cool itself, and body temperatures can rise to dangerous levels. Classic heat stroke is due to high environmental temperatures. Very young children, older adults, and though with chronic illnesses are most at risk. Exertional heat stroke is caused by internal body heat from high levels of exercise.
    • Irritability
    • Extremely dry mouth
    • Cessation of sweating
    • Skin that appears shriveled, lacks elasticity, red 
    • Little to no urination
    • Muscle cramping
    • Nausea, vomiting
    • Sunken eyes
    • Low blood pressure
    • Rapid heart rate and breathing
    • Fever
    • Confusion, irrational behavior, delirium
    • Unconsciousness

To prevent heat related illnesses, it's critical to pay attention to hydration. Water remains the best fluid for normal hydration, though all other fluids also work, though some not as well. Alcoholic beverages during excessive heat should be avoided due to their dehydrating effect. Caffeinated beverages have long been labeled dehydrating, though to its actual effect is now questioned for regular caffeine consumers. Even the food you eat contributes to a lesser degree. Water remains the top choice. Sports drinks contain sodium and other electrolytes that can be good for excessive sweating and when exercise lasts more than an hour.
When exercising in higher temperatures, it's critical to drink plenty of fluids before, during, and after exercise. Stick to early morning hours or after four for all strenuous outdoor activity. Interestingly, it's the well-trained athletes who are more at risk, due to their well-trained ability to sweat and lose more fluids. 

The need for fluid replacement goes up with:

  • Higher temperatures
  • Larger body size
  • Higher trained athletes
  • Increase in exercise intensity
  • Longer time outdoors
  • Longer the workout

You can drink too much. Extremely large water consumption can lead to a dangerous, hyper-hydrated state called hyponatremia, which can dilute sodium and other electrolyte concentration to life-threatening levels.

Heat can affect anyone. Pay attention to heat advisories and adjust your plans accordingly. When temperatures rise, start increasing water or other fluids throughout the day. Strive to keep your urine clear or straw colored.