Hydration & Heat-related Illness

Here in Sonoma County, we are expecting 7+ consecutive days of temperatures above 95 degrees. So, this seems like a good time to talk about hydration and heat-related illness.

Did you know that the ideal percentage of water in the average woman’s body is 45-60%? And when you exercise regularly, your body stores more glycogen to fuel that exercise. Glycogen binds with water as part of the process required to fuel your muscles. Therefore, the more you exercise, the more water you need above and beyond the body’s general needs.

Also, when the body gets hot (either from the environment, from activity, or both), the body cools itself by releasing water through sweat. Fluid lost through sweat, but not replaced through hydration leads to dehydration. Dehydration can be serious and can lead to a decrease in strength, a drop in endurance, and a reduction in motor skills. Dehydration can also lead to feelings of fatigue and may inhibit cognitive function.

The best way to prevent dehydration is to hydrate often and early. Hydrate before you start feeling thirsty because once you start feeling thirsty, you are already starting to dehydrate. As a general rule, you should plan to consume half of your weight (in pounds) in ounces of water daily. For example, if you weight 150 lbs, you should plan to consume 75 oz (150 x 50%) of water each day. This rule replaces the old saying “8 glasses of water a day”. Eight glasses, 64 oz, works well if you just so happen to weight 128 lbs (64 oz x 2).  However, the more you weigh, the more water your body needs to function properly.

And while we usually think that more of a good thing is always is a good thing, it is possible to drink too much water. While this is usually uncommon, it is more common in athletes (and yes, you are an athlete!) than in the general population since athletes are very concerned with replacing the fluids lost during exercise, especially in hot and humid environments. When your kidneys cannot excrete the excess water, the sodium content of your blood becomes diluted leading to a condition called hyponatremia, which can be life-threatening.  

Your urine should be a pale, yellow color. Dark urine (like the color of apple juice) indicates that you may be dehydrated and should hydrate more. On the flip side, completely clear urine does not necessarily indicate they you have overhydrated.  However, a good way to avoid hyponatremia is to make sure you are consuming sodium in addition to water when exercising, rather than just water alone. By including some sodium, you can ensure the sodium content of your blood does not get diluted to the point of hyponatremia. You can accomplish this by including oranges or watermelon slices in your hydration plan, if possible. Or you can carry salty snacks such as nuts, pretzels, and potato chips to consume with water while you exercise. While these are all awesome options for hiking, you may find it difficult to carry them on your long runs.  The portability of low-sugar sport drinks designed to combat dehydration and electrolyte replacement tablets make them ideal for scenarios when you are not carrying a cooler or backpack.

Dehydration is a minor illness that is easily remedied by hydration. However, dehydration can progress to heat exhaustion. The early warning signs of heat exhaustion are nausea, light-headedness, fatigue, muscle cramping and dizziness. It is imperative to recognize the warning signs and act on them as soon as possible.

At the first sign of heat exhaustion, it is important to take the following steps to help get your temperature down and cool your body:

  • Move to cooler place (under the shade of a tree or, if possible, inside)
  • Lower the body’s core temperature. Cold compresses or wet towels under the armpits are very effective in reducing the body’s core temperature. If you do not have access to a cold compress or towel, you can use a neck gaiter or bandana and wet it with water from your water bottle. If you have access to a cool stream, river, or lake that you can dip the neck gaiter/bandana into, even better! Neck gaiters/bandanas are small, lightweight and easy to stuff into a pocket or your waistband.  Like a whistle, I always carry a neck gaiter on long runs. I call it the “MacGyver Approach” to safety.
  • Remove tight or extra clothing layers
  • Replace fluids slowly. This is not the time to start chugging water or sports drink since heat exhaustion can impair your body’s ability to digest properly. Focus first on lowering the body’s core temperature and then replacing fluids slowly.

Heat exhaustion can progress to heat stroke. Unlike heat exhaustion, heat stroke requires immediate medical attention. Someone experiencing heat stroke may have a headache, confusion, no sweating, rapid heart rate, nausea or vomiting and may lose consciousness. When the body is hot to the touch and not sweating, you should immediately suspect heat stroke.  When heat stroke is suspected, it is vital to take the following steps:

  • Call 911 immediately
  • Move the person to a cooler place
  • Use cold compresses or other options to lower the body’s temperature
  • Do not give them fluids as their body will not be able to absorb them and you will only increase the probability of vomiting.

Finally, do not let all this talk about heat-related illness paralyze you. Knowing the enemy is the best way to overcome it! Now that you know the signs to look for, you can take appropriate precautions to ensure you do not experience them. Remember to hydrate early and often. And if you feel that you are may be suffering from heat exhaustion, take the appropriate steps to keep yourself safe. And do not forget to have fun out there!

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