Water is the largest component of the human body, making up 50 to 70% of the body’s weight. Lean muscle tissue contains about 73% body water; adipose (fat) tissue is about 20% water. Depending on how much fat has been stored, an adult can survive for about 9 weeks without eating food but only a few days without drinking water. This occurs not because water is more important than carbohydrate, fat, protein, vitamins or minerals but, rather, because there is no storage site for water.
Two main functions of water in the body include temperature regulation and removal of waste products. Most water comes from the liquids we consume. Some comes from the moisture in foods (especially fruits and vegetables), and the remainder is produced in the body as a metabolic byproduct. Water output includes that lost via the lungs, kidneys, skin and bowels. Water deficiency occurs if an individual is not drinking enough water. At this point, the body generally alerts us by signaling thirst; however, the thirst mechanism is not always reliable, especially during athletic practices and events, during illness and in one’s older years.
For this reason, athletes should weigh themselves before and after training sessions to determine their rate of water loss and thus their water needs. Progressive dehydration reduces sweating (our mechanism for cooling) and blood flow to the skin, which leads to excessive body heating.. It is essential to keep well hydrated before, during and following exercise, especially in the heat.
The following guidelines can help athletes maintain proper hydration during practice and competition in hot weather :
Weigh in without clothes before and after exercise, especially during hot weather. For each pound of body weight lost during exercise, drink two cups of fluid.
Drink a rehydration beverage containing sodium to quickly replenish lost body fluids. The beverage should also contain 6-8 percent glucose of sucrose (carbohydrate).
Drink 2.5 cups of fluid 2 hours before practice or competition.
Drink 1.5 cups of fluid 15 minutes before the event.
Drink at least one cup of fluid every 15 to 20 minutes during training and competition.
Some may worry about water toxicity (too much water). Water toxicity is whatever amount of water the kidneys are unable to excrete. This can lead to serious side effects; however, an excessive amount of water would have to approach many liters each day. Very few are at risk of drinking too much water. When excessive water overwhelms the kidneys’ capacity to excrete it, headache, cramps, blurred vision, convulsions and possibly death may occur.
