Heat Illnesses
Running unwisely under environmental heat stress may lead to a variety of heat illnesses
which can be life threatening. These illnesses are caused by three factors: increased core
temperature, loss of body fluids, and loss of electrolytes. While running in the heat, monitor
your condition for signs of weakness, dizziness, nausea, disorientation, cessation of sweating
and piloerection, the standing up of body hairs. If these signs occur, stop running and start
the appropriate treatment. They could be symptoms of any of the major heat illnesses
described below.
- Heat Cramps : Salts can be lost in the sweat while running in the heat. If they are not
replenished properly, muscle pain and cramps can occur. The body temperature does
not become elevated. Prevention can come from heat acclimatization, ingestion of large
amounts of water and by increasing the daily salt intake several days before the heat
stress. Treatment is rest in a cool environment and replacement of lost salts.
- Heat Exhaustion : Poor circulatory response to heat and reduction of blood volume due to
increased sweating can lead to symptoms of general weakness, dizziness and nausea.
The skin is usually cool and pale, but the person is probably still sweating. Body
temperature is not elevated to dangerous levels (under 106F). Exercise must be stopped.
Treat by rest in a cool environment, ingestion of cool liquids and cooling the body
externally with water or ice.
- Heat Stroke : When the body's temperature regulating system fails, excessively high body
temperature and heat stroke can result. This is a serious condition which, if untreated,
may well lead to death. It requires immediate medical attention. The symptoms are dry,
warm and red skin, a reduction or loss of sweat and a body core temperature over 106F.
Treatment is to immediately stop exercise, seek medical attention and start cooling the
body with ice packs and cold water. The person may or may not be conscious. Cool
liquids may be consumed if the person is conscious.
There are ways to reduce hazards when running in the heat and/or humidity, most are
common sense:
- Check the conditions before exercising and adjust your plan if needed. Slow the pace or
decrease the duration of activity if training when hot or humid. If racing when hot and
humid, realize that performance will less than expected. If the event is not a key one,
relax and save the bigger effort for a cooler day.
- Run in the early morning or late evening to avoid the heat of the day. In many climates,
late afternoon is the hottest time of the day and running then should be avoided.
- Find a shady road or trail to run on.
- Dress accordingly, wear as few clothes as you decently can. Try loose fitting white shorts
and a white mesh top to reflect the heat and to permit evaporation. Protect your head
from intense sun with a lightweight hat that can breathe. The back of the neck can be
protected by the hat or a cotton kerchief. Ice can be wrapped in the kerchief and carried
under the hat.
- Drink fluids while running. Carry a water bottle or pick a route with water fountains. Drink
6-8 oz. of water for every 15-20 minutes of running. Also pour water over your head and
chest.
- Weigh yourself daily and replenish lost water. Body weight should be back to normal
before the next workout.
- Try hyperhydration by drinking 2-4 cups of water 30 minutes before running.
- Be aware of lost electrolytes if you've sweated excessively. Put an appropriate amount
salt on foods and eat bananas and citrus fruit.
- Avoid excess protein intake. Protein metabolism produces extra heat.
- Know the signs and symptoms of heat illness and their treatments. If you have any of the
symptoms, stop running, get to a cool place and consume cold fluids.
- If you are going to compete in an event in hot conditions, acclimatize first.