Beat the Heat with Proper Hydration

With summer temperatures soaring to the 90 degree mark it’s more important than ever for people participating in outdoor activities to remember that nagging advice ” be sure to drink plenty of fluids”.   Whether you are running a marathon or simply cutting the grass, adequate fluid intake is essential for comfort, performance and safety. Dehydration is a major cause of fatigue, poor performance, decreased coordination, muscle cramping and even worse, the possibility of heat exhaustion or heat stroke.

How much is enough?

Do not rely on thirst alone to determine when and how much to drink.  Thirst is a poor indicator of the amount of fluids you may actually need – by the time you are thirsty, you may already be well on your way to dehydration.  During just one hour of moderate exercise, you can sweat away more than a quart of water.  An easy way to determine your fluid intake needs is to weigh yourself before and after exercise.  Weight changes reflect sweat losses (sorry, that two pounds wasn’t body fat). Each pound that you have lost sweating is equal to two cups or 16 ounces of fluid that you will need to replace accordingly.  So, if you have lost two pounds of sweat during an hour of exercise, you will need to consume two pounds or 32 ounces of fluids during each hour of future exercise.  This will work out to drinking 8 ounces every 15 minutes.  Prehydration is also important in preventing dehydration.  When preparing for strenuous exercise, drink at least 16 to 20 ounces of water two hours before exercise and another 8 ounces 15 to 30 minutes just prior to the activity.

Water or sports drinks?

Just plain water is probably the most appropriate choice for casual exercise and activities that last no more than an hour.  For more intense exercise lasting longer than an hour, such as running, cycling or rollerblading, it may be advantageous to consume a sports drink or diluted fruit juice providing 30 to 60 grams of carbohydrates per hour to delay fatigue and fuel muscle contractions.  It is really not necessary to replace losses of sodium, potassium and other electrolytes since it is unlikely you will deplete your body’s stores of these minerals during normal training.

If, however, you do exercise over 5 or 6 hours or in extreme conditions, such as a marathon or triathlon, you will want to use a complex sports drink that contains both carbohydrates and electrolytes.  Athletes who don’t consume electrolytes under these conditions risk overhydration from consuming excessive amounts of electrolyte free water, causing low blood sodium concentration or hyponatremia. A tip to athletes who train with water because it’s cheap and readily available, then decide to use a sports drink for competition – experiment prior to competition. Unfamiliar sports drinks may cause upset stomach, so it’s a good idea to find which one works best for you before the big event.

It is also a good idea to choose carbohydrate rich fluids such as recovery drinks or fruit juices that replace water losses and muscle glycogen to enhance recovery after exercise.
What about beer?

Beer is often a popular postexercise “recovery drink” but the alcohol in beer has a dehydrating effect that causes you to lose valuable fluids at a time when you should be replacing them.  If you intend to drink beer, quench your thirst first with water, eat something so you aren’t drinking on an empty stomach, and then enjoy a beer or two in moderation.

What about caffeine?

Caffeine has ergogenic properties and is often used pre-exercise for that extra energy boost.  Caffeine, however, also has diuretic properties causing your body to excrete fluid instead of retaining, so it’s not the wisest choice when you’re trying to retain proper hydration.

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