What Is Dehydration?
Dehydration occurs when your body loses sufficient water to affect performance and health. [Over-hydration, or hyponatremia, can be just as dangerous, or even more so. We’ll discuss that in another post.]
Your body uses water, in the form of sweat, to shed excess heat during hot-weather training. This water comes primarily from blood plasma. Unless you replace this water, your blood will thicken. This makes it harder for your heart to pump blood to your muscles, which deprives them of them oxygen that they need to perform. It also makes it harder for your heart to send blood to the capillaries near the surface of your skin, so your body has a harder time cooling off. The result: you slow down and heat up. As this occurs, you can move into heat exhaustion, and even heat stroke, which can be fatal.
What are the signs of dehydration?
1. Dry skin. You should always be sweating during aerobic exercise, particularly in the summertime. If your arms are bone-dry, you should take that as a warning sign that you need to start drinking more.
2. Cold or clammy skin. There’s no reason why you should be feeling cold on a hot summer day, unless your body is stressed from lack of water.
3. Nausea. A big warning sign!
4. Disorientation. This is a tough one to spot, but here’s a tip: try to think of some fact or list you should be able to remember, like your home address when you where growing up, your high school teachers, or your favorite cousin’s phone number. During your run, see if you can still remember your chosen fact. If you’re having trouble recalling it, you might be heading to dehydration.
Do I Stay Hydrated?
Proper hydration occurs slowly, so the best strategy is to drink regularly, both during training and throughout the day. To get an idea of how much fluid you can lose during training, weigh yourself before and after exercise to see how much weight you’ve lost. Not all of this is water — you’ve also burned calories from stored fuel and used electrolytes — but much of it is due to water loss.
You might be surprised to find that on a hot day, it’s not unusual to lose five pounds of water. And remember: a 2% loss in body fluid can seriously affect exercise performance, and further loss of fluids can be dangerous. So your strategy should be to drink regularly before and after exercise, and to replace lost fluid by taking a sip every five to ten minutes during exercise.
So, what should you drink? Water is the old standby and will serve you well, but a sports drink not only replaces lost fluids, but also essential minerals that are crucial to proper muscle function and health, and simple sugars to provide some quick energy.
What Can I do if I Get Dehydrated?
Remember: heat stroke doesn’t suddenly happen. Before you hit the danger zone, there are warning signs and a progression of symptoms. The earlier you spot these and react to them, the better your chances of staying out of trouble.
The first thing you need to do once you recognize that you’re experiencing one of the signs of dehydration is to slow down and take in fluids as soon as possible. Get something to drink wherever you can: a fountain, a friend with water to share, or a convenience store. Don’t be proud: you can slurp water from a garden hose, or knock on someone’s door and explain the problem. You might be surprised to find that people are usually happy to help out.
Also, try to cool off as quickly as possible. Pour cool water on your wrists, and over your arms and head. Wet your cap or sweatband and put it back on your head. If you don’t feel better, sit down in a shady area and rest until you do feel better.
And finally, if you still don’t feel better, seek medical help. Call 911. Don’t be brave; this is a potentially dangerous situation, and if you’re still not feeling well, emergency medical care can save your life.
If you follow these tips and keep aware of how you’re feeling, there’s no reason why you need to be afraid of the hot summer days. Train Smart, and have fun!