Table of Contents:

[ Health / Dietary / Liquid ]
[ Carbohydrate / Fat / Protein ]
[ Vitamin / References ]

How much liquid does a student athlete need?
Water makes up to 70% of total body weight. An average 75kg human contains about 60% or 45 liters of water (Sawka and Pandolf, 1990). Student athletes with lean body and low fat mass have higher water content. The fluid losses of student athletes depend upon the the intensity at which the student athlete is exercising, an individual genetic predisposition for sweating, his or her level of fitness, the environmental and climatic conditions, and the amount and type of clothing and headgear worn by the student athlete (Sawaka and Wenger, 1988). During low intensity exercise in cool and dry settings sweat loss can be less than 500 ml/h. In hot and humid conditions during intense exercise sweat loss may exceed 3 litres/hour (Sawka and Pandolf, 1990). Therefore, fluid intake should be carefully monitored to ensure that fluid needs during these conditions are met by adequate intake.

Under normal conditions the water content of the body is constant. An imbalance between fluid intake and fluid losses results in dehydration (Brouns, 1993). The volume of fluid varies widely among athletes but in general the amount of fluid needed to compensate for the fluid lost is about 50% of the sweat loss (Noakes et. al., 1988).

Even slight dehydration can have noticeable and negative effects on performance during high intensity exercise. Dehydration causes fluid imbalances in the body that can lead to impaired mental focus, impaired energy metabolism, and important changes in electrolyte concentration levels. Plasma fluid volume plays an important role in maintaining a normal blood flow through the tissues.

Dehydration causes a decrease in plasma volume, and as a result leads to decreased blood flow. This will lead to reduced transport of substrates and oxygen to the muscles needed for energy production. This will result in decreased energy and a marked, rapid onset of fatigue (Brouns, 1993).

The American College of Sports Medicine (ACSM) recommends that athletes regardless of sport should ensure that they are well hydrated before training or competition. Athletes should drink at least 500 ml (about 16 oz) of fluid (water, juice, sports drink) 2 hours before exercise. When the urine is darkly colored, and the urine volume is low the student athlete is in a dehydrated physical state and should consume more fluid until the urine returns to a normal, clear or very light amber color. To assure adequate hydration prior to training and competition athletes should consider ingesting an additional 250 -500 ml of fluid 30 minutes before exercise.

Athletes should stay well hydrated before and during exercise, and make sure that cool fluid is available at all times, because cool fluid leaves the stomach more quickly. Drinks can be flavored and sweetened sufficiently to encourage student athletes to drink. One teaspoon of salt per liter helps to ensure complete hydration and normalize the body's sodium levels. Some commercially available sports beverages are available and can be used to sustain normal electrolyte levels (ACSM, 1996; Broad, 1996; Burke, 1995).

Team sports: Athletes who are involved in team sports such as soccer have tended in the past to limit fluid intake to the half-time break. This is not adequate for maintaining optimal fluid levels in the body. Student athletes should drink fluids freely on an as needed basis. Coaches and team trainers should encourage student athletes to drink at all times, and attention should be given to student athletes with above average sweat rates to make sure they are drinking appropriately (Broad, 1996; Burke, 1995).

Short duration and high intensity sports: Athletes involved in high intensity sports can experience rapid and significant dehydration. Depending on the level of competition, efforts of less than 30 seconds do not involve significant dehydration (Horswill, 1991). However, participation involving extreme efforts of greater than 30 seconds in duration can cause rapid weight loss from fluid depletion (Horswill, 1994).

Long duration moderate intensity sports: Athletes who compete in long distance running, cycling, and skiing events that last longer than 30 minutes generally have access to fluids at regular intervals. Sometimes runners restrict fluid intake when experiencing gastrointestinal problems that are already due to dehydration, and increase the effects of dehydration. Student athletes need to practice in training drinking habits that will be effective in maintaining adequate body fluid levels during competition.