How to keep your body working by keeping it hydrated Published May 30, 2006 By Tech. Sgt. Heather Tevebaugh Human Performance Training Team, 319 Air Refueling Wing GRAND FORKS AFB, N.D. -- Some of us think of sweat as an annoying thing our body does to let everyone else know we are either too hot or nervous. In reality, it is our body’ s way of regulating temperature. Your body can lose between one and a half and two and a half liters of water per hour, but it can only reabsorb one per hour. That means in times of strenuous activity, increased temperatures, while wearing you chemical defense gear, or playing outside, our bodies can not regain water as fast as they lose it. Physiologically speaking, there is a specific chain of events that occur as you dehydrate. At a 2 percent loss, your mouth becomes dry and you feel thirsty. At a 3 to 6 percent loss, you may feel discomfort, weariness, sleepiness or develop dizziness or a headache. As dehydration continues, your sweat rate decreases, blood volume is reduced and cardiac output is decreased, which can lead to heat illness. Performance is also affected by dehydration. By the time you are thirsty, your ability to perform decreases by 10 percent. There is also increased risk of mishaps and injuries. Most of us are pretty aware of heat-related illnesses such as heat cramps, exhaustion and stroke, but dehydration can cause even more problems. Dehydration is inevitably followed by omission errors, routine tasks taking longer, fatigue coming faster and even degraded vision. What can you do to prevent it? Hydration is an ongoing process. You should maintain one liter of hydrating fluid each hour. Don’t wait until you are thirsty to drink, because by that time you are already dehydrated. Drink beyond your feeling of thirst, because your thirst sensation will be satisfied long before you are rehydrated. You will know you are okay when you’ve drank enough to use the bathroom at least four times a day, and have light-yellow colored urine. Water is the best performance fluid for any physical activity that lasts less than 90 minutes. It absorbs quickly into your blood stream and has fewer drawbacks than other fluids. If you get tired of plain water, add something with only a few calories to it. You should avoid caffeine; it actually draws water from your body. In fact, juice and caffeine-free soda contain so much sugar that your body must use the water in the drink and in your own system to break it down. Also, electrolyte replacement drinks only provide benefits after 60 to 90 minutes of sustained strenuous activity. Before that, or while you are sitting at your desk, they are just added calories. For more information on proper hydration, contact your health and wellness center.