Shoulder pads add to athletes’ cool

All those fist-pumping, end zone-dancing hot dogs in the NFL have a new way to keep their cool: air-conditioned shoulder pads.

Blowing cool, dry air underneath football pads after vigorous exercise appears to hold core temperature down, reduce heart rate and provide the player with a sense of being cooler, researchers at the University of Florida report.

The specially designed pads have been used during games (on the sidelines) by a number of NFL and college teams -- including the Dallas Cowboys, Indianapolis Colts, Jacksonville Jaguars and UCLA Bruins -- but hadn’t been tested for their effects on actual temperature, says lead author MaryBeth Horodyski, director of research at the university’s Department of Orthopaedics and Rehabilitation.

Even small reductions in core temperature can be important, she says. “Many don’t realize that it’s not uncommon for athletes, particularly football players in the Southeast in August and September, to have core body temperatures over 103 when competing.”

But as the body temperature approaches 104 degrees, a person can begin to experience exertional heat illness, which can result in a range of symptoms, including feeling light-headed and slight nausea. Further increases in temperature put the person at risk of heat stroke.

Horodyski, who has no financial interest in the equipment, presented the results last week, at the annual meeting of the American Orthopaedic Society for Sports Medicine in Orlando. The investigators tested 15 athletes under two conditions in a room heated to 92 degrees.

In the first condition, the athletes performed treadmill jogging and sprinting while wearing a T-shirt, shoulder pads, shorts, football jersey over the pads, and helmet. In the second, the same athletes performed the same exercise, but had air cooled to 60 to 65 degrees pumped through special shoulder pads during the rest and recovery sessions.

In both conditions the athletes completed three 15-minute exercise sessions separated by 10-minute rest periods, followed by a 20-minute recovery.

At regular intervals, the researchers measured core temperature (via an ingested sensor), heart rate, body weight and fluid intake. They also measured the participants’ subjective impressions, such as perceived body heat and thirst.

The subjects in the cooling group posted significant differences in core body temperature at the end of the second rest cycle and at five, 10 and 15 minutes into the recovery period. The largest difference was during recovery, when the cooling group posted an average core body temperature of 100.3 degrees Fahrenheit, versus 101.7 degrees for the control group.

Athletes in the cooling group also recorded a notably lower average heartbeat than the control group, by about eight to 10 beats a minute.

“It is extremely important to test out new devices in randomized controlled trials like this one,” says Rebecca Lopez, a heat and hydration researcher at the University of Connecticut.

Improperly used, cooling devices could lead athletes to assume their body temperature is lower than it is.

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janet.cromley@latimes.com