HEAT STRESS

Joseph Lee, M.D.

We have all been saddened by the recent deaths of the high school, college, and pro athletes related to heat stress.  The saddest part of these stories is that heat related illness (and death) is preventable and should not occur in supervised athletic activity.  We have to be aware of the risks that severe summer weather poses for our children and take the appropriate steps to prevent heat related illness.

Exercising children do not adapt to extremely hot temperatures as effectively as adults for several reasons:

1.    Children have a greater surface area to body mass ratio resulting in greater heat gain from the environment on a hot and humid day.

2.    Children produce more metabolic heat for their size than adults during physical activity.

3.    Sweating capacity is lower in children than adults reducing their ability to cool by evaporation.

Dehydration or lack of adequate hydration results in an excessive increase in core body temperature and places the child at a much greater risk for heat related illness.  Because children often do not recognize the need to drink enough to replace fluid during exercise, it is important that coaches and parents insist on adequate fluid replacement.  Water is ideal, but sometimes children will accept flavored sport drinks better and drink more.  Thirst is enhanced with the small amount of added salt in these drinks. 

The American Academy of Pediatrics recommends the following guidelines for children and adolescents.

1. The intensity of activities that last over 15 minutes should be reduced when temperature and humidity are at extremely high levels.  This can be done by increasing rest periods with water breaks and by frequent substitution of players.

2. At the beginning of a strenuous exercise program, the intensity and duration of       exercise should be  limited initially and gradually increased over 10-14 days to allow acclimatization to the heat.  If such a time period is not available, the practice and competitive time should be curtailed.

3. Before prolonged physical activity, the child should be well hydrated.  During the activity, periodic drinking should be enforced – every 20 minutes 5 ounces of cold water or a sports drink for a child weighing 90 lbs. and 9 ounces for an adolescent weighing 130 lbs. even if the child doesn’t feel thirsty.  A child should not lose weight when exercising if he or she is receiving adequate fluids. 

4. Clothing should be light colored and lightweight and limited to one layer of absorbent material to improve evaporation of sweat.  Because football players have to wear heavier protective equipment, frequent breaks and substitutions area must.

Finally, talk to your child about heat related illness.  Tell him that it is extremely important to let the coach know if he is feeling sick or dizzy or weak during practice.  He must stop exercising and cool off.  Stress the importance of drinking adequately during practice or games.

If we all work together, we can prevent a heat related tragedy happening to one of our young athletes.