A FIT LIFE
Steve Infanti

Q: Does wearing a full uniform pose any health risks during football practice in the summer?

A: First, monitor wet-bulb temperature. Wet-bulb temperature is a combined measure of temperature and humidity. In general, it provides information about the cooling capacity of the environment, that is, how much sweat can evaporate and cool the body at a given air temperature. It is measured with a regular thermometer by placing a wet cotton "sock" over the bulb. As water evaporates from the bulb, the temperature goes down some.

In sports, the military, and industry, they use "wet-bulb globe temperature" or WBGT to measure how much total heat stress there is on a given day. Globe temperature measures radiation, like sunlight, which adds to the heat stress on the body.

Football uniforms, like other clothing ensembles, limit free evaporation of sweat from the skin. That's why they add to the heat burden and make body core temperature rise more quickly, notes Tasha J. Kulka of Penn State.

Kulka, who has researched clothing specific environmental limits for football, points out that over one-million males participate in American football each year. The timing of the beginning of their season—August to early September—coincides with the hottest and most humid part of the summer in many parts of the country.

"As ambient temperature increases, radiation and convection heat losses are decreased. Therefore, loss of heat through evaporation becomes an important mechanism to dissipate heat in any hot and wet or dry environment," explains Kulka. "The protective equipment required in football poses a precarious balance between protection related to the sport and harm from the thermal environment."

The clothing’s effect, in combination with metabolic heat production, can overwhelm an athlete’s heat dissipation mechanisms, causing serious heat stress complications.

If you’re exercising or playing sports in the heat and humidity, there are some precautions that you should follow, according Dr. W. Larry Kenney, professor of physiology and kinesiology at Penn State.

"Gradually allow your body to adjust to exercise in the heat. The full process usually takes 9-14 days and most heat illness occurs in un-acclimated exercisers. Acclimation results in a higher sweating rate, more dilute sweat, lower heart rates and lower core temperatures," says Kenney.

Maximize fluid intake before, during, and after exercise. If practice or the game lasts longer than 60 minutes or involves high-intensity intermittent bursts (like football, soccer, etc.) sports drinks like Gatorade provide a continuous source of energy while allowing the fluid to be absorbed into the body, adds Kenney. Mildly salting food during hot seasons is a good practice for those athletes without a history of hypertension.

During practice, frequent breaks that allow players to take off their helmets and rehydrate are essential.

(Steve Infanti edits the research magazine for Penn State’s College of Health and Human Development. Send your health, fitness and nutrition questions to Steve Infanti, "A Fit Life," 216 Henderson Building, University Park, PA 16802 or via e-mail at )