HYDRATION
Your body depends on water to survive. Every cell,
tissue, and organ in your body needs water to
work correctly. For example, your body uses water
to maintain its temperature, remove waste, and
lubricate joints. Water is needed for good health.
Water makes up more than half of your body
weight and you lose water each day when you
go to the bathroom, sweat, and even when you
breathe. You lose water even faster when the
weather is hot, when you are physically active,
or if you have a fever, vomiting or diarrhea.
If you don’t replace this lost water daily, you
can become dehydrated.
DEHYDRATION
Symptoms of dehydration include the following:
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Little or no urine, or urine that is darker than usual
Dry mouth
Sleepiness or fatigue
Extreme thirst
Headache
Confusion
Dizziness or lightheaded feeling
No tears when crying
Actively prevent dehydration by drinking plenty of
water daily.
People are at higher risk of dehydration if they exercise at
high intensity, have certain medical conditions, are sick,
or are not able to get enough fluids during the day. Older
adults are also at higher risk, as their brains may not be able
to sense dehydration and send the signals for thirst.
You also need to increase the amount of water you drink
if you:
■■ Have certain medical conditions such as kidney stones
of bladder infections
■■ Are pregnant or breastfeeding
■■ Will be outside during hot weather
■■ Will be exercising
■■ Have a fever, been vomiting or have diarrhea
■■ Are trying to lose weight
HYPONATREMIA
Although rare, drinking too much water can be as much of
a problem as not drinking enough water. This condition is
called hyponatremia (water intoxication). Drinking excessive
amounts of water can cause a low concentration of sodium
in the blood, which is a serious medical emergency.
Symptom of hyponatremia can be similar to dehydration,
but because of the loss of sodium in the blood these
symptoms can also be indications of more serious medical
conditions. Athletes in particular need to be cautious and
replace sodium as well as fluids during exercise to avoid
hyponatremia.
STAYING HYDRATED
There have been many different recommendations for daily
water intake, the most common is to drink 6 to 8 eight
ounce glasses of water each day, which is a reasonable
goal. However, like with most things every body is different
and so different people need different amounts of water
to stay hydrated. Most people can listen to their body and
stay hydrated by drinking water and other fluids when they
feel thirsty. For some people more than 8 glasses is needed,
for others less will keep them well hydrated. The best way
to know if you are drinking enough water is to check your
urine. If your urine is consistently colorless or light yellow,
you are most likely staying well hydrated. Dark yellow or
amber-colored urine is a sign of dehydration.
SPORTS DRINKS
For most people water is all that is needed for good
hydration. However, if you are planning to exercise at a high
intensity for longer than an hour, a sports drink may be
helpful because it contains carbohydrates and electrolytes
that can increase your energy and help your body absorb
water.
Choose a sports drink wisely. They are often high in calories
from added sugar and may contain high levels of sodium
and/or caffine. And check the serving size. One bottle may
contain several servings, so if you drink the whole bottle you
may be doubling or tripling the amounts on the Nutritional
Facts Label.
Sports drinks and energy drinks are NOT the same.
Energy drinks usually contain large amounts of caffeine and
other stimulants such as guarana, ginseng or taurine, which
your body doesn’t need. Many are also high in added sugar.
Many experts recommend that children and teens not have
energy drinks.
EASY WAYS TO STAY HYDRATED
■■ Keep a bottle of water with you during the day. Use
a refillable bottle to reduce plastic waste and your
expense.
■■ If you don’t like the taste of plain water, put a slice of
lemon or lime in your drink.
■■ Be sure to drink water before, during and after a
workout.
■■ Thirst is often confused with hunger, so if you feel
hungry drink a glass of water first. True hunger will
not be satisfied by water.
■■ If you have trouble remembering to drink water, drink
on a schedule. For example, drink water when you
wake up; at breakfast, lunch and dinner; and when
you go to bed. Or drink a small glass of water at the
beginning of each hour.
■■ Drink water for the most part, but if you don’t mind
the extra calories mix it up by including fruit and
vegetable juices, milk and herbal teas in your daily
intake routine.
■■ Water can also be found in fruits and vegetables, for
example watermelon, tomatoes and lettuce; and in
soup broths.
HYDRATION AND SPORTS
Staying hydrated is essential for everyone, but athletes
have an even greater need to maintain proper hydration.
Adequate fluid intake before, during and after exercise or
sports is essential to comfort, performance and safety. The
longer and more intense you exercise, the more important it
is to drink the right kind of fluids.
Studies have shown that athletes that lose as little as 2%
of their body weight through sweating has a drop in blood
volume which causes the heart to work harder to circulate
blood. A drop in blood volume may also lead to muscle
cramps, dizziness, fatigue and heat illness including heat
stroke and heat exhaustion.
HYDRATION NEEDS FOR ATHLETES
Because there is a wide variety of sweat rates, losses and
hydration levels of individuals, it is nearly impossible to
provide specific recommendations or guidelines about the
type or amount of fluids athletes should consume.
Finding the right amount of fluid to drink depends on a
variety of individual factors including temperature, altitude,
the length and intensity of the activity and other individual
factors, however there are two simple methods to determine
if you are adequately hydrated.
1. Monitor your urine volume output and color. A large
amount of light colored, diluted urine probably means
you are hydrated. Dark colored concentrated urine
probably means you are dehydrated.
2. Weight yourself before and after exercise. Any weight
loss is most likely from fluid, so try to drink enough to
replenish those losses. Any weight gain could mean
you are drinking more than you need.
The American College of Sports Medicine suggests that
“individuals should develop customized fluid replacement
programs that prevent (greater than 2 percent body weight
reductions from baseline body weight) dehydration. The
routine measurement of pre- and post-exercise body weights
is useful for determining sweat rates and customized
fluid replacement programs. Consumption of beverages
containing electrolytes and carbohydrates can help sustain
fluid-electrolyte balance and exercise performance.”
While specific recommendations aren’t possible as noted
above, most athletes can use the following guidelines as a
starting point and modify their fluid needs accordingly:
HYDRATION BEFORE EXERCISE
■■ Drink about 15-20 fluid ounces, 2-3 hours before
exercise
■■ Drink 8-10 fluid ounces, 10-15 minutes before exercise
HYDRATION DURING EXERCISE
■■ Drink 8-10 fluid ounces every 10-15 minutes during
exercise
■■ If exercising more than 90 minutes, drink 8-10 fluid
ounces of a sports drink (with no more than 8 percent
carbohydrates) every 15-30 minutes
HYDRATION AFTER EXERCISING
■■ Weight yourself before and after exercise and replace
fluid losses.
■■ Drink 20-24 fluid ounces of water for every 1 pound
lost.
■■ Consume a ratio 4:1 ratio of carbohydrate to protein
within the 2 hours after exercise to replenish glycogen
stores.
Sources
Consensus Statement of the 1st International Exercise-Associated
Hyponatremia Consensus Development Conference, Cape Town,
South Africa 2005. Clinical Journal of Sport Medicine.
15(4):208-213, July 2005.
Exercise and Fluid Replacement, ACSM Position Stand, American
College Of Sports Medicine, Medicine and Science In Sports &
Exercise, 2007.
Institute of Medicine. Water. In: Dietary Reference Intakes for
Water, Sodium, Cholride, Potassium and Sulfate, Washington, D.C:
National Academy Press, pp. 73–185, 2005.
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