The key to hydration Published June 4, 2015 By Capt. Sarah Kercher 14th Medical Operations Squadron LAUGHLIN AIR FORCE BASE, Texas -- As the summer months progress here at Laughlin, it's wise to review the importance of preventing heat stress. An important element to that prevention is to stay hydrated. Did you know that over 60 percent of the human body is made up of water and all of our major body systems rely on that water to function? The cells in our body are filled with water, the plasma in our blood contains about 92 percent water, our brains are 70 percent and the lungs are nearly 90 percent water. Water regulates body temperature, lubricates joints and aids in the transportation of nutrients for energy. It is important that we don't allow ourselves to get dehydrated; it will affect every aspect of the body. We must replenish the fluids that are lost continuously through sweat, urination and even breathing. Maintaining proper hydration is incredibly important and it becomes much more important when you're exposed to the Del Rio heat. But, you may ask, how do I know if I'm dehydrated? Dehydration can have many subtle signs and symptoms that include fatigue, dry mouth and lips, confusion, dizziness, constipation, little to no urine output or dark urine color, headache and thirst. If you're running low on fluids, your body has trouble maintaining a constant core temperature, partially due to the decreased sweat rate and decreased skin blood flow, which are two of your body's mechanisms for maintaining proper internal temperature. Your ability to tolerate heat becomes more challenging and your endurance, strength and power will also decline. Every one of us strives to optimize our human performance, but even with excellent fitness, our performance can decrease by up to 50 percent simply from dehydration alone. The thirst sensation typically doesn't occur until you're already two to three percent dehydrated, which means you've lost two to three percent of your body weight in water. Your body is able to regulate water concentration and at certain levels, it signals your brain to give you a thirst sensation. Truth is, we often don't drink as much as we need to make up for the deficit. The thirst sensation is much like a warning that goes off when you're mildly dehydrated but doesn't intensify proportionally with increased dehydration, even if we don't hydrate as necessary. So then, how much water should you be drinking? Eight eight-ounce glasses of water? One quart per hour? Ideally, you should drink enough to avoid being thirsty. My advice is to consume half your body weight in ounces, so for a 150-pound person, that would be 75 ounces per day. Any fluid, excluding alcohol, can count towards this total, including foods that are high in water content, like watermelon, soups, leafy greens and tomatoes. If water is not your drink of choice, there are alternatives such as juice, sports drinks and flavored water. If you choose these alternatives, keep in mind that the calories in these drinks can add up fast. Sports drinks are not necessary unless an individual is experiencing high amounts of sweat loss from either heat exposure or high-intensity workouts that last longer than an hour, at which point sports drinks should be consumed in small amounts. They provide salt, potassium and other vitamins and minerals which aid your body in retaining the water. Bottom line: hydration is important because it allows your body to function at its optimal level. It not only increases your performance but also decreases fatigue, which is a benefit that anyone will enjoy. Grab a glass of ice cold water and enjoy! Capt. Sarah Kercher was with the 47th Medical Operations Squadron when she wrote this in 2011.