Introduction

Water is an essential nutrient that represents approximately 60% of a person's body. It plays a critical role in athletic endeavors. During training or competition, an athlete will lose fluid through the skin as sweat and through the lungs while breathing. Additional fluid is lost on a normal occurrence through the urine and feces. If proper fluid replenishment is not met, dehydration may occur. Dehydration is excessive water loss, which decreases the blood volume circulating throughout the body. Consequently, this also decreases the amount of blood pumped with each heartbeat, which also reduces the amount of oxygen working muscles receive, thus causing exhaustion. This chain of events significantly decreases an athlete's performance. Research shows that a loss as little as 2% body weight can negatively affect performance. Fluid replacement is key to dehydration prevention and reducing the risk of heat cramps, heat exhaustion and heat stroke.

Signs and Symptoms of Dehydration

How to Determine Dehydration

Several techniques have been used to estimate hydration status: Urine Color Urine Osmolality Bioelectric Impedance to indicate total body weight Before and after activity weigh-ins Thirst The easiest way to determine dehydration, besides thirst (when its often too late) is to compare your urine to the urine chart, included below. Urine Chart The target is to achieve numbers 1, 2 or 3. Numbers 4 and 5 suggest dehydration. Numbers 6, 7 and 8 indicating severe dehydration.

Proper Fluid Replacement

Before Exercise 17 fluid ounces (500ml), 2 hours prior to exercise This promotes adequate hydration Allows time for excretion of excess ingested water During Exercise Consume fluids at a rate sufficient to replace water lost through sweating, OR Consume maximal amount that can be tolerated Exercise less then 1 hour Drink plain water There is no evidence proving a carbohydrate and electrolyte mixture will make a difference Exercise longer then an hour Consume 5-12 fl oz (150-350ml) every 15-20 minutes Choose a sports drink that contains 4-8% carbohydrates 30-60g carbohydrates per hour Sodium 0.5-0.7 per liter After Exercise Need to replenish water and sodium loses Normal fluid & food at meal time is usually sufficient When exercise sessions are at least 24 hours apart Re-Hydration Re-hydrate within 6 hours of exercise A total of 2 liters (68 fl oz, 2000ml) 17 fl oz (500ml) Every 20-30 minutes Requires water & sodium Consuming at intervals 20-30 minutes is more efficient then consuming all at once Rapid fluid replacement after exercise stimulates increased urine production, resulting in a decrease in water retention Sports Drinks Sports drinks are an excellent fueling and hydration source. Research shows that sports drinks significantly boost endurance when exercise lasts 60 minutes or longer, in comparison to water. Composed of carbohydrates (sugars) and water, sports drinks come in a wide variety of flavors. Possible sugars include: sucrose, glucose, fructose, galactose and maltodextrins, which can be seen on the nutrition label on the back of the product. A blend of different carbohydrate sources has been proven to improve the amount of carbohydrate that eventually gets to the muscle as fuel. This is a result of sugars being absorbed by different routes, thus improving absorption rate. Some come with added electrolytes. Sodium helps maintain fluid balance and promotes fluid uptake in your intestines, thus improves hydration. What to Look For: A blend of sugars (carbohydrates) at 4-9% solution or 13-19g of carbohydrates per eight ounces. Drinking 1 ½ - 4 cups per hour, depending on the length and intensity of activity. Although "fitness waters" are tasty and keep you hydrated, they don't provide enough carbohydrates to boost endurance. Carbohydrate Gels Gels come in small, single serve packages that are easily squeezed into your mouth on the run. They have a pudding-like texture and come in a variety of flavors. Gels consist of easily digested sugars, like sports drinks but without the water. Some even come with added electrolyte that can help fluid balance. Caffeine may also be added to the gels in varying amounts. This can cause nervousness in those not accustom to it. What to Look For: About 100 calories and about 25 carbohydrates. Consume 3 packets for every hour of intense exercise. Take with 4-8 ounces of water.

Prevention

Tips on Dehydration Prevention and Proper Hydration Choose a beverage that tastes good This will help promote fluid consumption Avoid carbonated drinks May cause GI distress and decrease the volume of fluid consumed Avoid beverages that contain caffeine and alcohol Do Not try a new fluid replacement drink on a day of competition. Use the trial and error approach during practice, until you find what works for you. Monitor fluid losses Weigh-in before and after training Be sure to replace fluid loss For every pound lost, drink about 3 cups of fluid Do Not restrict fluids before, during or after activity Do Not rely on thirst as an indicator Keep an eye on urine color Be aware of your environment during activity Hot, dry weather increases risks of dehydration and heat illnesses Prepare ahead of time for such conditions