We are fortunate to live in a beautiful city surrounded by water where in typical years it seems water falls from the sky more often then not. Come August and early September we might find ourselves seeking out the coolness of the lakes for relief from the hot, dry days. But water is good for more than a beautiful vista or a kayak trip through the Montlake Cut, it is the most essential nutrient in the body. One of the most important roles that water plays is to maintain normal body temperature by carrying heat away from internal organs before damage occurs. In hot weather, water intake becomes even more important because dehydration and heat stress can set in with little warning even if you are laying on a raft on Lake Washington. 

Dehydration occurs when fluid loss exceeds intake. Fluid is lost through sweat, urine and water vapor in the breath we exhale. Heat exposure, fever, vomiting and diarrhea can all cause dehydration. The symptoms of dehydration include increased thirst, weakness and dizziness and in some cases heart palpitations and fainting can occur. The calf cramp you get from a long walk down Lake Washington Boulevard on a hot day may be from dehydration and changes in electrolyte balance. 

Prevention of dehydration comes down to planning ahead. If you’re headed to the Music in the Park on a hot evening make sure to hydrate throughout the morning and early afternoon. Your body requires 8-10 glasses of water or clear fluids a day and you should drink often enough to prevent thirst. Once you feel thirsty you’ve probably already lost about 1% of your body water and may be dehydrated. If plain water isn’t appealing, squeeze a lemon or lime in it for flavor (plus you will add antioxidants in the form of Vitamin C). Alcohol consumption increases water loss and can impair your ability to sense early signs of dehydration. If you’re lucky enough to come across a sidewalk lemonade stand you should take advantage of the opportunity to top off your fluid balance while making the neighborhood kids happy. 

Food provides 20% of normal fluid intake and eating 5 cups of fruits and vegetables per day will help maintain hydration and provide the important nutrient potassium. Muscle function, bone strength and nerve signaling all depend on adequate potassium. Many fruits and vegetables contain 90% or more water. Fresh, juicy fruits are refreshing and many contain essential electrolytes such as calcium, magnesium, potassium, and sodium. Hit Bert’s Red Apple and grab a watermelon, apples, kiwi, grapefruit and berries to snack on. Vegetables such as celery, escarole, spinach, and broccoli and water-based clear soups such as vegetable soup will help prevent dehydration. 

Exercising and outdoor events should be limited when the thermometer crosses 80 degrees and the heat index is high. Competitive and recreational athletes need to take extra precautions when training or competing in the heat. A fluid loss of 2% is not only dangerous but can also reduce performance by 10%. It is possible to lose over 60 ounces of water per hour when exercising in the heat. Taking in 6-8 ounces of fluid every 15 minutes is needed during events when the temperature soars. A typical cycling water bottle holds 20 to 24 ounces meaning you should consume 1 per hour of exercise. When exercising over an hour in the heat a sports drink should be used to meet fluid, electrolyte and carbohydrate needs. The benefits of adequate fluid intake during exercise include lower heart rate, improved blood flow to muscles, body temperature control, lower perceived exertion, and quick recovery. 

Being active and enjoying the warm weather requires a little more planning on hot days. Add a juicy fruit and an extra glass of water to your daily routine. You’re body will thank you.

AARON SHAW is a registered and licensed occupational therapist, certified hand therapist and certified strength and conditioning specialist. He operates MoveMend, a clinic located at 2818 E. Madison St. in Seattle.