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Tips for Staying Safe in the Heat

By Lewis Maharam, MD, FACSM
Medical director, NYRR and ING New York City Marathon

• Respect your limits. Heat and humidity increase the physical challenge of running, and health
problems can occur when you push beyond what your body can handle. Do not aim for a personal best
on a warm, sticky day, particularly if you are not used to such conditions.

• Acclimate. It takes 10 days to two weeks for the body to acclimate to keeping cool at higher
temperatures. Give your body time to adjust.

• Know the signs of heat problems. If you feel faint, dizzy, disoriented, have stopped sweating, or your
skin is cool and clammy, slow down or stop running. If symptoms continue, sit or lie down in the shade
and seek help.

• Drink enough. Drink throughout the day, so that your urine remains plentiful and clear or pale yellow.
Even mild dehydration (scant, dark-yellow urine) will make you feel sluggish and tire early during
exercise, and can increase the risk of heat-related problems during exercise. Water is fine for
hydration, but in the heat, sports drinks are even better because the sugar and salt they contain form
an “active pump” that transports fluid to cells more quickly than water alone. Before workouts or races
lasting longer than one hour in the heat, drink 16 ounces of fluid several hours in advance, another 16
ounces in the hour before, and more just before the start if your urine isn’t pale or clear.

• Don’t drink too much. Overhydrating before and during exercise can cause a dangerous condition
known as hyponatremia (water intoxication). This drop in the body’s sodium levels can cause nausea,
fatigue, vomiting, weakness, and in the most severe cases, seizures, coma, and death. To avoid
hyponatremia, do not overdrink, include pretzels or a salted bagel in your pre-run meal, and use a
sports drink that contains sodium. During exercise, drink no more than a cup of fluid every 15 to 20
minutes.

• Skip the ephedra. Avoid supplements containing ephedra (or its synthetic version, ephedrine), which
increases the risk of heat illness by raising metabolism and inhibiting sweating.

• Wear synthetic fabrics. Unlike cotton, synthetics wick moisture from your skin so cooling evaporation
can occur. Synthetics also decrease chafing and don’t cling and cause a chill. Look for loose-fitting
garments with mesh inserts under the arms, on the sides of the torso, down the arms, and on the
outer thighs. Acrylic socks keep feet dry and cool.

• Use water along the course (cups, spray stations) to cool yourself during races. If you are
overheating, a cool spray will cool you down quickly and have a lasting effect as the water evaporates
from your skin. Keep in mind, though, that drenched clothing will cling to skin and prevent evaporation,
and wet socks can cause blisters, so use this strategy wisely.