With the warm weather fast approaching, the topic of
proper hydration comes to mind. Every year there is at
least one high school football fatality from heat illness
and many people suffer needlessly due to poor
hydration habits. Here is an article I wrote for the
Montgomery County Road Runners Club:
With proper preparation, life-threatening heat illness
is avoidable. Both heat exposure and dehydration will
diminish an athlete's ability to train and complete;
however, even if an athlete is well hydrated, hot
weather alone can cause heat illness. When the rate
of heat production by the body exceeds the rate of heat
dissipation the thermoregulatory system may become
overloaded and cause heat cramps, heat exhaustion,
or heat stroke.
Heat cramps typically begin as muscle
twitching and can progress to localized contractions of
the muscles of the legs, arms, or abdomen.
Treatment includes cessation of the activity, moving to
a cool, shaded area, drinking cold water, and using
gentle massage and stretching of the cramped area.
Before returning to running the cramp and the pain
should be completely gone.
Heat exhaustion is a form of shock due to the
inability of the body to meet demands of blood flow to
skeletal muscle (exercise) and skin (heat
dissipation). Signs and symptoms are weakness,
fatigue, profuse sweating, dizziness, fainting,
headache, nausea, diarrhea, loss of mental clarity,
increased body temperature, increased heart rate,
decreased blood pressure, muscle cramps, and loss
of coordination. Treatment includes
cessation of
running; moving to cool, shaded area; monitoring
temperature, pulse, and blood pressure; body cooling
with cold water or ice; slow rehydration with cold water
or sports drink per the person's tolerance. If
symptoms worsen, call 911. Do not return to activity
the same day. Recovery is usually complete within
12 - 48 hours.
Heat stroke is a medical emergency requiring
rapid diagnosis and treatment. Signs and symptoms
fall into three groups: decline of mental acuity
(confusion, forgets details, cannot follow progress of
game/race); bizarre behavior (combativeness, loss of
temper, blank stare); physical decline (unsteadiness,
loss of coordination, nausea/vomiting/diarrhea,
unconsciousness, seizure, body temperature >104° F,
rapid/shallow breathing, rapid/weak pulse, and
decreased blood pressure). 911 must be called
IMMEDIATELY. The person must be placed in a cold
(ice) bath as quickly as possible (and removed once
temperature drops below 102° F). Have the person
sip cold water or sports drink until EMS arrives. A
health care profession should determine a return to
activity date. Heat stroke can cause permanent heat
intolerance.
Increased susceptibility to heat illness can be caused
by: previous heat difficulties, poor conditioning and
acclimatization, obesity, sun burn, heart disease, skin
disease, fever, inappropriate clothing, certain
medications (beta-blockers, cyclic antidepressants,
diuretics, antihistamines, antibiotics), cystic fibrosis,
mental retardation, use of ephedra or other stimulant
supplement, pushing too hard.
Hyponatremia means too little sodium in the
blood. It is caused by overhydration. More common in
both slower runners and women, hyponatremia can
be deadly. Symptoms include weakness, nausea,
pounding headache, dizziness, vomiting, delirium,
bloating, and swollen fingers and ankles. Fluid intake
must be optimized, not maximized. No fluid should be
given until urination has begun and salty foods are
encouraged.
Dehydration - loss of body fluid - reduces the
body's capacity for heat loss. If you are thirsty, you are
about 2% dehydrated. This can cause loss of energy
and impaired performance. A 5% loss can cause
gastrointestinal problems (nausea, vomiting) and
muscle cramps. At 7% coordination loss and
hallucinations may occur and a 10% loss may result
in circulatory collapse and death.
High sweat rates can cause large losses that worsen
dehydration. In 1984 Alberto Salazar lost 8.1% of his
body weight during his 2 hour 14 minute Olympic
race. He lost 1 pound of body weight every 12
minutes.
Here are some guidelines to optimize your
performance and prevent hyperthermia and
dehydration:
1. Acclimate to the heat over 10 - 14 days. Do not
compete in a race if you have not had a chance to
acclimate to the heat!
2. Do not run outside when the heat index is over 100
and the air quality index is in the red (unhealthy). Run
early in the day or train inside.
3. Weigh yourself before and after your run. Drink 16
ounces of cold fluid for each pound lost. You cannot
rehydrate by guzzling, so drink throughout the
remainder of the day. This is especially important
when training on a daily basis in the hot weather.
4. Look at the brim of a cap for that white ring to see if
you are a salty sweater. You may need sodium
tablets for runs over one hour.
5. Prehydrate by drinking 16 ounces about 30 minutes
before you run. Adjust as necessary.
6. If your urine is darker than a chardonnay wine color,
you are dehydrated.
7. If your heart rate remains elevated after a run, drink
cold water take an ice bath.
8. After a run, cool yourself immediately. Get out of the
sun and into a cool environment. At a race, bring a
cooler with an ice pack and rub the ice pack over your
head, arms, and legs for a few minutes. A great
product is called Ice-Up, an ice cup with in its own
cooler that stays frozen for up to 10 hours. At home,
take a cold shower or bath.
9. Wear light colored, lightweight, moisture wicking
clothing and a similar hat.
10. Wear sunscreen with an SPF of at least 15.