Not enough water? Dehydration. Too much water and/or not enough salt? Hyponatremia. Both can make you feel really sick and send you to the hospital. If you just walk for 30-60 minutes, you may never have a big problem. But if you are on a long hike or walking a 10K, half marathon, or marathon, these can be big problems. One of my walking buddies ended a grueling, sweaty, mountainous half marathon feeling like she had hyponatremia. What is the difference?
Hyponatremia is a condition in which your water and salt balance is off. Walkers may get hyponatremia by drinking plenty of water but losing salt with sweating and not replenishing salt. Signs of hyponatremia include nausea, headache, cramps and bloating. A study of runners in the Boston Marathon found that 13% of the slower runners developed hyponatremia, and it can cause heart arrhythmia and even kill you.
Dehydration is usually the biggest concern for walkers and runners, as many people don't want to carry the extra weight of a water bottle or large enough hydration pack. The current guidelines are to drink when you are thirsty. It's hard to do that if you are relying on water fountains. I find that using a Camelbak hydration pack is my best way to keep the water handy. For walks of over an hour, especially in warmer weather, it's wise to switch to an electrolyte-replacement sports drink so you are replacing both lost water and lost salt.
Weigh Yourself: If you are going to be walking long distance in warm weather, you should test yourself to see if you are drinking enough or too much using the method suggested by the International Marathon Medical Directors Association. Weigh yourself before and during your long walk or run. You shouldn't gain or lose any weight -- if you are drinking the right amount. My walking buddies and I tested this and I was drinking right based on thirst, while one of my buddies was dehydrated. Having watched her get sick on a half marathon and marathon, I now understand that she has to be reminded to keep drinking.
Drinking alerts: If you don't trust your thirst, you can set an alarm on your watche or cell phone to remind you to drink every 20 minutes or every mile. With an app like Walkmeter, the mile announcement can be your reminder to take a drink.
Photo © Wendy Bumgardner