Endurance athletes, especially those training multiple times during a 24 hours period, are at particular risk for dehydration due to fluid losses from sweating. Losses of fluids are due to intensive exercise, warm weather, extreme humidity or high altitude.
Even minimal dehydration (1-2 percent) body weight loss can hinder the performance by reducing blood volume. This results in the ability to maintain a safe core temperature. Also, it reduces the amount of oxygenated blood pumped to working muscles.
For exercise-induced losses, the endurance athlete should weigh before and after training to determine the amount of fluid lost through sweating. For every 1 kg lost after exercise, the athlete needs to drink 1250 ml of fluid over the next few hours to meet fluid needs and associated obligatory urine losses that occur during rehydration.
Mild dehydration ( <2 percent ) body weight loss is often unavoidable during endurance exercise, particularly during physical endeavors and competitions lasting longer than 3 hours because the athlete cannot always replenish fluids at rate that matches the fluid being lost. For example, the capacity of the gastrointestinal tract, particularly the rate which ingested fluids empty from the stomach, may become maximized and thus serves to limit the athlete’s intake of fluid. Gastric emptying rates and tolerance to large volumes of fluids in the stomach vary wildly among individuals. During training sessions, endurance athletes are advised to train there GI tract to drink in an attempt to enhance their ability to tolerate drinking larger volumes of fluid.
Fitness levels and sweat rates and consequently fluid and electrolyte needs vary widely among athletes, so do the environmental conditions. There is no one-size fits all hydration guidelines. To ensure optimal hydration, endurance athlete must personally establish and monitor their personal fluid needs. Over hydration is as dangerous as dehydration.
Athletes who gain weight during exercise for example, after running marathon or participating in a 100 mile bike ride, will need to hydrate less, Athletes should drink according to thirst with the general recommendation of no more than 400-800 ml per hours.
A gradual weight loss, often mistaken as fat loss, Accompanied by fatigue or slow recovery and small amounts of dark-colored urine with a strong odor can indicated a dehydrated state. Dehydration can best be prevented by making rehydration a priority after the previous day’s exercise and drinking small amounts throughout the day to maximize absorption. Two hours before exercise, 500 ml of fluid need to be given.
Athletes who take part in endurance events such as marathons, triathlons and adventure races need to master drinking and eating while literally in the move.
- Carry large volume of fluid, sport drink or food.
- Practice drinking and eating on the move
- Take fluid energy (from CHO source) and electrolyte (particularly sodium) needs
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