Once again, triple-digit temperatures surround us and the hotter we get, the thirstier we feel. “Don’t get dehydrated” is as commonly heard here in Arizona as “it’s a dry heat” so everywhere you go you see people with their water bottles. Which is a good thing, don’t get me wrong. But just like most things that are good for us, did you know that too much water could turn into a bad thing? Over-hydration is as potentially a life-threatening situation as is under-hydration. Now the average Joe or Jane is not risking anything as they down their requisite number of ounces of water during the day. It’s the athletes attempting to maintain their work-out regimens in the heat of the day that are a concern, or workers required to carry out their duties in the heat of the day. Well intentioned as it may be, as these individuals attempt to avoid dehydration, they may in fact end up drinking too much water and slip into over-hydration. Too much water could be considered a poison. No kidding; it does happen.
As always, a little bit of anatomy and physiology is necessary to better understand the topic at hand. More than half of the human body is actually water. Women should be approximately 50 percent water and men should be approximately 60 percent water.
Three body systems: skin, lungs, and kidneys are responsible for contributing to the maintenance of the delicate balance necessary for optimum cellular functioning called homeostasis. Essentially, the skin maintains the temperature of the water environment within the body. We perspire when our insides get too hot and we shiver when our insides get too cold. The lungs breathe in oxygen so the cells can metabolize energy and they breathe out carbon dioxide, a by-product of that metabolism. Lastly, the kidneys are responsible for maintaining the body’s electrolytes within certain ranges. Electrolytes are minerals (mostly sodium, potassium and chloride). When there is too much water surrounding our body’s cells, the level of sodium is diluted compared to the levels within the cells.
To maintain homeostasis water will flow into the cells actually causing them to swell. When the levels of any of these electrolytes move out of their normal ranges, the body can experience a variety of symptoms that represent the effect that the imbalances have on other major body organs such as the heart and brain.
Adequate sodium balance is necessary for transmitting nerve impulses and proper muscle function, and a major deviation of this concentration can cause problems. This is particularly evident by the earliest signs of water intoxication, which occur due to swelling of brain cells: headache, personality or behavior changes, confusion, irritability or drowsiness. Later symptoms of water intoxication include a heart rate that is too slow, muscle weakness, cramping, nausea and vomiting and seizures. The body cannot function optimally when its water/electrolyte environment is disrupted. If not recognized and treated appropriately, death could ensue.
The American College of Sports Medicine recommends if you are exercising regularly, you will probably need between one half and one whole ounce of water for each pound of body weight per day, or at least 1-2 liters depending upon your body mass. To determine your baseline range for water requirements, use the following formula:
• Low end of range: Body weight in pounds x 0.5 = ounces of fluid/day.
• High end of range: Body weight in pounds x 1 = ounces of fluid/day.
For example, if you weigh 150 pounds, your approximate water requirement will be between 75 and 150 ounces each day. And now, factor in exercise or vigorous activity: One to two hours before your workout, drink 15 to 20 ounces of water; 15 minutes before you begin, drink between 8 and 10 ounces of water; during your workout, drink another 8 ounces every 15 minutes.
Thirst is an important indicator during and after physical activity, especially in hot environmental conditions. However, the clear and important health message should be that thirst alone is not the best sign of dehydration of the body’s fluid needs and is often a late sign. Dehydration represents the opposite end of the spectrum from over-hydration and results from the failure to adequately replace lost fluids. This can lead to elevated body core temperatures and increases strain on the cardiovascular system.
Maintaining proper levels of hydration is difficult, especially for those who are not acclimated for strenuous activity in hot environments. Exercise early in the morning and calculate the number of ounces of water you need for your daily level of activity.
• Agnes Oblas is an adult nurse practitioner with a private practice and residence in Ahwatukee Foothills. For questions, or if there is a topic you would like her to address, call (602) 405-6320 or email firstname.lastname@example.org. Her website is www.newpathshealth.com.