Dehydration is a serious concern during outdoor activities, especially during hot summer months – although it can happen during colder months too. It can happen in summer or winter, on a day hike or several days into a long hike, even during normal daily activities.
Vigorous activity, excessive sun exposure, forgotten water breaks, and medical conditions are a few factors that can affect your hydration level.
Some of the consequences of dehydration are loss of energy and motivation, irritability, headaches, difficulty sleeping, fainting, hypothermia, and frostbite. In extreme cases, dehydration can lead to delirium and even death.
Essentially, if you‘re losing more fluids than you‘re taking in, dehydration is the result. So it‘s important to stay sufficiently hydrated while hiking, backpacking, or any time.
Signs and Symptoms of Dehydration
The rule for judging whether someone is becoming dehydrated is the phrase, “Clear and Copious”. This means that one‘s urine should not have a strong color and that urination should be fairly frequent. If your urine is not clear like gin to pale yellow, you are dehydrated. Dark yellow indicates serious dehydration.
It takes time for the body to absorb fluids, so you must drink early and often. Saving your water for later can result in dehydration instead. Thirst is not necessarily an indicator of dehydration. The body‘s thirst signal starts when you are 2 to 5 percent dehydrated. That person who is acting crankier than usual may be dehydrated, so take frequent water breaks.
Rate of Moisture Loss
We lose moisture in our breath and by sweating. For example, during eight hours of sleep about one quart of moisture is lost through breathing and another quart is lost through perspiration. The rate is even faster when exercising vigorously.
How Much Water?
The basic rule for avoiding dehydration is to drink plenty of fluids, but this doesn‘t means just any fluid. Diuretics (such as caffeine, alcohol, and a number of medicines), promote dehydration. The body does not absorb highly sugared or carbonated beverages as rapidly, which means that soft drinks are less efficient at quenching thirst than plain water. And some adults down a few soda beverages at the end of a hot day believing that they are rehydrating, but research shows quite the opposite.
The best way to keep hydrated or to rehydrate is with plain water or water with one of the specially developed rehydration mixes added (sports drinks like Gatorade, etc).
Someone exercising hard may lose more than a quart of water an hour. So a good guideline for vigorous activities at altitude is a minimum of 4 quarts a day (a gallon), up to as much as 8 quarts. For example, this might mean consuming a quart at breakfast (including hot drinks and fluids in cereal and fruit), one quart between breakfast and lunch (take frequent water breaks), a half-quart with lunch, a quart between lunch and supper (more water breaks), and a final quart at supper (including in the form of soups, hot drinks, and the main course).
Many people find that staying well-hydrated is key to a good night‘s sleep. Remember that caffeine is a diuretic, so coffee, tea, and chocolate are not as effective as non-caffeinated drinks.
Good resource for this type of information:
LDS Preparedness Manual, 2012 Edition