Drink plenty of liquids
before, during and after workouts and competitions.
Dehydration can affect a swimmer's performance in less
than an hour of exercise, even sooner if you begin the session dehydrated.
And yes, you DO sweat and can become dehydrated
during a good workout in a swimming pool.
Dehydration of just one to two percent of body weight can
negatively influence performance. Dehydration of greater than three percent
of body weight increases an athlete's risk of heat illness (heat cramps,
heat exhaustion, heat stroke).
Signs & symptoms of dehydration
- Fatigue and/or loss of energy.
- Headache or body ache.
- Dry mouth.
- Urine is dark colored.
- Very dry mouth.
- Diminished amount of urine.
- Increased dizziness.
- Skin is less firm.
- Rapid and weak pulse.
- Changes in mental state (disorientation/memory loss).
Severe to Life-threatening Dehydration
- Loss of consciousness.
- Sunken looking eyes.
- Extremely dry mouth and cannot swallow.
- Swollen tongue.
Recommendations for Hydration to Prevent Heat Illness
from the Journal of Athletic Training: 35(2): 212-224; NFHS Handbook
Heat Related Illness, Sandra Shultz Phd, ATC, CSCS, Steven Zinder
SPORTS DRINKS TO DRINK
- Examples: Water, Gatorade,
10K, Quickick, Max
- These drinks are absorbed as quickly as water and typically
are used for activities lasting less than 2 hours.
- Examples: Gatorlode, Exceed
- These drinks replace more muscle glycogen to enhance
greater endurance. They should be used after ultra-endurance events to
increase muscle glycogen resynthesis after exercise.
- Examples: Gatorpro, Exceed
Sports, Ultra Energy
- These supplements are fortified with vitamins and minerals
and they help athletes maintain a balanced diet. They can be used as a
meal replacement supplement for athletes who wish to skip a high fat meal,
or as extra calories for athletes who wish to gain weight.
- Drinks with Carbohydrate (CHO) concentrations of greater
than eight percent should be avoided.
- Fruit juices, CHO gels, sodas, and sports drinks that
have a CHO greater than six to eight percent are not recommended during
exercise as sole beverages.
- Beverages containing caffeine, alcohol, and carbonation
are not to be used because of the high risk of dehydration associated with
excess urine production, or decreased voluntary fluid intake.
TO PREVENT HEAT ILLNESS
- Drink according to a schedule based on individual fluid
- Drink before, during and after practices and games.
- Drink 17-20 ounces of water or sports drinks with six
to eight percent CHO, two to three hours before exercise.
- Drink another 7-10 ounces of water or sport drink 10
to 20 minutes before exercise.
- Drink early - By the time you're thirsty, you're already
- In general, every 10-20 minutes drink at least 7-10 ounces
of water or sports drink to maintain hydration, and remember to drink beyond
- Drink fluids based on the amount of sweat and urine loss.
- Within two hours, drink enough to replace any weight
loss from exercise.
- Drink approximately 20-24 ounces of sports drink per
pound of weight loss.
- Dehydration usually occurs with a weight loss of two
percent of body weight or more.
TO DRINK DURING EXERCISE
- If exercise lasts more than 45-50 minutes or is intense,
a sports drink should be provided during the session.
- The carbohydrate concentration in the ideal fluid replacement
solution should be in the range of six to eight percent CHO.
- During events when a high rate of fluid intake is necessary
to sustain hydration, sports drinks with less than seven percent
CHO should be used to optimize fluid delivery. These sports drinks have
a faster gastric emptying rate and thus aid in hydration.
- Sports drinks with a CHO content of 10 percent have a
slow gastric emptying rate and contribute to dehydration and should be
avoided during exercise.
- Fluids with salt (sodium chloride) are beneficial to
increasing thirst and voluntary fluid intake as well as offsetting the
amount of fluid lost with sweat.
- Salt should never be added to drinks, and salt tablets
should be avoided.
- Cool beverages at temperatures between 50 to 59 degrees
Fahrenheit are recommended for best results with fluid replacement.
PERFORMANCE AND RELATIONSHIP TO HEAT ILLNESS
- Dehydration can affect an athlete's performance in less
than an hour of exercise - sooner if the athlete begins the session dehydrated.
- Dehydration of just one to two percent of body weight
(only 1.5-3 lb.. for a 150-pound athlete) can negatively influence performance.
- Dehydration of greater than three percent of body weight
increases an athlete's risk of heat illness (heat cramps, heat exhaustion,
- High-body-fat athletes can have a harder time with exercise
and can become dehydrated faster than lower-body-fat athletes working out
under the same environmental conditions.
- Poor acclimatization/fitness levels can greatly contribute
to an athlete's dehydration problems.
- Medications/fevers greatly affect an athlete's dehydration
- Environmental temperature and humidity both contribute
to dehydration and heat illnesses.
- Clothing, such as dark, bulky, or rubber protective equipment
can drastically increase the chance of heat illness and dehydration.
- A relative humidity of 35 percent and a temperature of
95 degrees Fahrenheit are likely to cause heat illness, with heat stroke
- A relative humidity of 70 percent and a temperature of
95 degrees Fahrenheit are very likely to cause heat illness, with heat
stroke very likely.