Fluids and Hydration for Fitness and Sport

Proper hydration can make or break your athletic performance

© 2002 Wadsworth Publishing / Thomson Learning™

Fluid Needs and Regulation of Body Temperature

Water is essential for all cells

The body is about 55-60% water

2/3 of the water is inside cells

Normal body temperature is 98 degrees

Avg. person needs ~1 qt. Per 1000 kcal

© 2002 Wadsworth Publishing / Thomson Learning™

Fluid Input and Output© 2002 Wadsworth Publishing / Thomson Learning™

The Electrolytes

Sodium, Potassium, Chloride, Calcium, Magnesium, and Sulfate

Conduct electrical currentsMost sweat loss is water lossSodium, Potassium, and Chloride may be

lost during excessive exercise in the heatSee page 123 for food sources, functions,

and deficiencies

Hydration

Thirst is not a reliable indicator of fluid needs

General guideline: 2-3 C of fluids per each pound of weight loss during activity

Drink fluid freely 24 hours before the eventDrink 1.5-2.5 C two-three hours before the

eventConsume 3-8 ounces every 15 minutes for

events lasting longer than 30 min.

Fluid Losses and Their Effect on Performance

At 3% water loss, performance shown to decrease 10%

See page 124 for adverse symptoms

Heat Exhaustion

A depletion of blood volume from fluid loss by the body

Body heat is lost primarily through evaporation of sweat

Fluid loss through sweat is about 3-8 C per hour

Humidity interferes with sweat productionDecreases endurance, strength, performanceProfuse sweating, headache, dizziness,

nausea, weakness, visual disturbances

Heat Cramp

Occurs in the skeletal muscleA complication of heat exhaustionPainful muscle contractions for 1-3

minutes at a timeEnsure athletes have adequate salt

and fluid intakeExercise moderately at first in the

heat

Heat Stroke

Internal body temperature reaches 105єF

Symptoms: nausea, confusion, irritability, poor coordination, seizures, and coma

Athletes should replace fluids and monitor weight change (fluid loss)

Avoid exercising under hot, humid conditions

Sports Drink For Endurance Exercise

Recommended for activity > 60 minutes in duration (water best before then)

Sweat, CHO, and electrolytes lost in events <60 minutes are easily replaced by diet

For events > 60 min. sports drink can help maintain blood glucose level and blood volume

Sports Drinks

Diabetics bewareSugar, water, and

NaGlucose polymer &

fructose combo6% & 15 gm per

cup

Sound Guidelines for Fluid Replacement and Keeping Cool

Keep fluids accessible and cool (40-50 degrees)

Hydrate well for air travelWear suitable clothing for hot or cold

weatherAvoid salt tablets (diarrhea and

irritation)Acclimatize to an area before

competition there

Sound Guidelines for Fluid Replacement and Keeping Cool

You should have four full bladders a dayAvoid caffeine and alcohol that dehydrateUse 6% carb concentrationDrink 2 cups water for every pound lostHydrate with water 20-40 minutes before

exerciseHydrate during exercise 3-8 oz. Every 10-

15 minutes

Sound Guidelines for Fluid Replacement and Keeping Cool

Drink water after exerciseLarger volumes of water absorb more

rapidlyCool fluids leave the stomach more rapidly

to be absorbed by the small intestineWorking above 75% of your maximum

heart rate makes absorption more difficultDrink before you are thirsty

Sound Guidelines for Fluid Replacement and Keeping Cool

Some people react to sports drinks negatively even at proper concentration nausea stomach discomfort dehydration blood sugar drop early glycogen release

Sound Guidelines for Fluid Replacement and Keeping Cool

Use water for up to 90 minutes

Use a combo of glucose polymers and

fructose after 90 minutes

Choose purified water over tap water

whenever possible

Hyperhydrate before a major hot event

Hyperhydration

Excessive intake of waterIntake without sodium and

chlorideDuring prolong low intensity

activitiesResults in low blood sodium and

low blood chloride