Rehydrating

If you’re dehydrated, just drinking a glass of water may not immediately solve the problem, although it certainly starts the rehydration process. Complete water replacement throughout the body—rehydration—may take twenty-four to forty-eight hours no matter how much you drink at one time. Unfortunately, the human body does not function like that of many other animals. By drinking a large volume of water, dehydrated animals can consume 10 percent of their total body weight in a few minutes and rehydrate quickly.

Humans, however, need to drink water in smaller amounts much more frequently to correct dehydration and maintain proper water balance. For example, after a long or hard workout, drinking sixteen ounces (500 mL) of water every thirty minutes is more effective for rehydration than drinking a very large amount at one time. A large dose of water at one time can impair the thirst mechanism and promote a diuretic response—so you can actually lose more water than normal through urine. (In addition, when drinking a large amount of water at one time, many athletes inadvertently swallow too much air, which can cause bloating.)

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Here are some general guidelines to prevent dehydration and maintain proper water balance:

 

 

 
  • Drink water every day, throughout the day—don’t wait until you’re thirsty.
  • Drink smaller amounts every couple hours rather than larger volumes at one time.
  • Have water available at all times, and get into the habit of drinking small amounts all day.
  • Avoid carbonated water as your main source; the carbonation may cause intestinal distress.
  • Learn to drink water without swallowing air—drink slowly and without tilting your head up and back. Air in the stomach is a common cause of distress, especially during competition.
  • Avoid chlorinated and fluoridated water; chlorine can be toxic, and fluoride impairs energy production.
  • An average-sized athlete may need about three to four quarts of water each day, depending on the individual, the types of training, and the environment.
  • Get used to drinking water before and immediately after workouts. When training for more than about an hour, drink small to moderate amounts of water during the workout.
  • About three hours before long, hard, or competitive events, drink at least sixteen ounces of water, and about half that much water about fifteen minutes before the start of activity.
  • During activity lasting more than an hour drink about ten ounces of water every twenty minutes.

Over-hydrating—drinking high volumes of water right before training or competition—does not help reduce the effects of dehydration. Also avoid glycerol-based products, which may not help hydration and can cause intestinal distress. Instead, maintain adequate water intake every day up to and during physical activity as needed.

In addition to the above recommendations, get used to drinking water as your main source of liquid in the course of the day between meals. While it’s true you obtain some of your water needs through food and other beverages, most should come from plain water, consumed between meals. Certain drinks such as coffee, tea, and alcohol can increase your need for water because of their diuretic effect (causing the body to lose water). So don’t rely on these beverages as part of your water intake. (Even decaf coffee and tea can contain small amounts of caffeine.) Higher levels of protein consumption also increase the need for water.

Retaining the water you drink following workouts and competition can also be accomplished with the addition of sodium, from food or drink. Tomato or vegetable juices, soups, and other salty foods can be very helpful to rehydrate. Sodium tablets can also be effective if the dose is carefully calculated. The addition of sodium also will also stimulate your desire for more water intake.

Athletes are quickly affected by dehydration. Runners can reduce their pace by 2 percent for each percentage of body weight lost by dehydration. Water losses of 6 percent to 10 percent may occur in a triathlon or marathon. Even shorter events are affected by dehydration; a 10K race run in thirty-five minutes under normal hydration can slow to almost thirty-eight minutes when the runner is 4 percent dehydrated. In addition, since dehydration causes an elevated heart rate, it’s not unusual to find a plateau or worsening in the MAF Test when an athlete is dehydrated.

In addition, temperature regulation can be significantly affected during dehydration. The ability to expel heat, especially during long or hard events or in hot weather, is reduced. This can raise body temperature, reducing the function of the brain, muscles, and metabolism. Cooling the skin with water, especially dumping water over your head, can be helpful.

The aerobic system can help water regulation, in part due to the significant amount of blood vessels that make up the aerobic fibers. In athletes with a good aerobic base, water regulation is more efficient and body temperature and sweating function more effectively.

Athletes completing long or hard training, and especially competition, who have nausea, vomiting, or diarrhea, or those who are unable to consume water because of the same problems, may require intravenous fluid replacement. This often occurs in triathlons, marathons, and ultramarathons, especially in hot weather. It’s not uncommon for those in team competition to have intravenous fluid replacement, including those in football, soccer, and other sports.