Hydration and Sports Performance
Water is the athlete!s most important nutrient.
Even a 1-2% fluid loss can cause significant performance deterioration by increasing
core body temperature and causing early fatigue. A 3-5% fluid loss increases stress on
the heart and decreases the ability to dissipate heat. By 7% collapse is likely, and the
signs and symptoms of heat illness will be evident and the risk of heat stroke and
catastrophic complications can follow.
It is not uncommon for players to dehydrate 2-4% during practices or games (or up to
6% when training in the heat). Children do not regulate their body temperatures as well as adults so the hydration habit is even more important for them.
How Much Should the Athlete Drink?
Determining the individual!s fluid needs is probably the single most performance
enhancing aspect of sport nutrition. The best way to determine individual hydration needs is to weigh the player before and after practice. After removing sweat soaked clothes, each pound of weight lost represents about 16 ounces or 1/2 litre of fluids lost. Another simple method of determining hydration status is to observe the color of one's urine. A color darker than a pale yellow indicates dehydration (some vitamin supplements also make the urine darker in color).
The following are only guidelines as each player will have specific needs according to
many variables:
• Begin prehydrating the body at least 24 hours prior to competition
• Drink about 5 ml. of water per kilogram body weight a couple hours before the game
• Sip fluids during the practice or game when possible - Ideally, take about 5 sips every
15 minutes.
• After the game, replenish fluids, carbohydrates and electrolytes. Rehydrate with 16
ounces or 500 ml. of fluid per pound of body weight lost.
• Daily needs are estimated at 1/2 - 2/3 ounce of water per pound of body weight
depending on activity levels.
Sport Drinks vs Water?
Sport drinks contain carbohydrate (sugars) and electrolytes to help replace components
lost in sweat. The carbohydrates in sport drinks vary between 6-8%, an amount
considered ideal to replenish fuel and still allow fluids to empty from the stomach
rapidly. This said, not all players tolerate sport drinks near or during competition and others find that they must dilute the drink to avoid stomach upset. Most of the
professional players I have seen drink only water in and around game time. Research
suggests that sport drinks are perhaps more useful than water for activities lasting
longer than an hour.
Remember, each player has individual needs so game day is not the time to experiment
with a sport drink. As our muscles are extremely receptive to carbohydrate replacement
immediately after exercise, a sport drink can be a useful recovery tool. In a research
study at the University of Texas, athletes drank either a diet pop, a 6% carbohydrate
drink, or plain water for a 2 hour, post-workout rehydration period. Pop drinkers
regained on average 54% of their lost sweat. Water drinkers regained an average of
65%, while those who consumed the 6% carbohydrate drink regained a whopping 73%
of their body weight lost to sweat.
The type of fluid replacement and the schedule of fluid replacement should occur early
in the season before competitions begin.
Signs of Dehydration
- Decreased endurance
- Increased heart rate
- Muscle cramps
- heavy sweating
- Decreased concentration
- Urine color darker than a pale yellow
Maintenance of ideal body hydration improves the performance, recovery and
regeneration of the player. A well hydrated player will run further, faster, and more often.
There is less stress on the heart; performance inhibitors such as early fatigue and
muscle cramping are reduced or eliminated.
Water is the athlete!s most important nutrient.
Yours in Sport and Health,
JR Justesen
Director, Goal-Tek Innovations Ltd.
Director, Parkway Physiotherapy and Performance Centre
JR is a physiotherapist, soccer player, coach and father. He has worked in amateur and
professional soccer as a physiotherapist, and has written a book on soccer safety. The
Ultimate Guide to Soccer Safety is available free of charge at www.goal-tek.com.