"Heat illness is a big problem," McFarlin said. "Despite the fact that it has been known to be a big problem for at least 50 years, there hasn't been good data to suggest what the exact risk factors are that contribute to heat related illness."

The environmental chamber is like a giant cooler—10 X 20, wall-to-wall stainless steel—where researchers control the temperature and humidity. The space can be heated up to 120 degree Fahrenheit or cooled to minus four degrees Fahrenheit to mimic the climate conditions in workouts, like two-a-day practices in the heat or winter outdoor bike rides. Subjects ride a stationary bike in the hot or cold chamber. Their heart and blood are monitored.

"Our group is interested in how exercise disturbs the immune system," Associate Professor Brian McFarlin said. "Houston has a climate that is very prone to extreme amounts of heat, especially in the spring and summer months. Exercising in that environment may have very pronounced effects on the body and not really positive effects."

The environmental chamber at the department's Laboratory of Integrated Physiology resembles a giant cooler. At 10 feet by 10 feet, the temperature and humidity of the wall-to-wall stainless steel room can be adjusted from 120 degrees Fahrenheit to minus four degrees Fahrenheit. Subjects' blood and body temperature are monitored as they work out on stationary bikes. McFarlin says other institutions have environmental chambers, but not many are used to collect data on a problem that has touched the lives of the very elderly and the very young.