How athletic trainers use science to shield athletes from the heat

SAN ANTONIO – As fall approaches in South Texas, high school stadiums come alive with cheers, marching bands and the cadence of football.

But it’s not just the opposing team athletes battling; it’s the brutal heat.

With daily highs often pushing past 90 degrees and turf temperatures spiking as high as 140°F, student-athletes are training under conditions that can quickly turn deadly.

At the University of the Incarnate Word, athletic training professor Dr. Reid Fisher has spent over a decade preparing students for this reality.

“There’s layers of prevention you can do,” Fisher said. “Mistakes have been made if you have to respond to someone being ill.”

That prevention begins with education and science.

From wet bulb globe thermometers that factor in humidity, sunlight, and airflow, to infrared tools that measure radiant heat from turf, today’s athletic trainers rely on real-time data to guide every decision.

Fisher notes that at 120 degrees, even cleats begin to deform.

“So if that’s what’s happening to the shoes, imagine what’s happening to the feet inside them,” he adds.

UIL heat guidelines

To help schools adapt, the University Interscholastic League (UIL) has set clear heat protocol guidelines using wet bulb temperature— not just air temperature.

Here’s a breakdown of the UIL’s wet bulb temperature guidelines:

These limits are based on wet bulb temperature, which, unlike standard thermometers, reflects how effectively sweat can evaporate off the skin — a significant component in cooling the body.

What is the goal?

To keep core body temperatures from rising above 104°F, the threshold is the point at which organ failure and heat stroke become a serious risk.

But it’s not just about when to stop practicing; it’s about how to prepare for one. Hydration, for example, isn’t just about offering water.

Trainers at UIW track individual sweat rates, monitor electrolyte loss and require athletes to weigh in and out of sessions.

Losing just one percent of body weight in sweat can impair performance. At 10%, the body loses the ability to cool itself — and that’s when medical emergencies occur.

“If you’re just drinking water, your body’s going to filter it back out,” Fisher said. “Without electrolytes, you can’t actually pull that water into your tissues where it’s needed.”

Some challenges go beyond biology. According to Fisher, even the playing surface can affect athlete safety in unexpected ways. Synthetic turf fields, especially under direct sun, can retain so much heat that they create localized hot zones—even impacting nearby air temperatures.

“There are suggestions that synthetic fields can create their own weather patterns,” Fisher said.

Despite the high-tech tools and protocols, Fisher believes the most important element of heat safety is collaboration.

Coaches, administrators and trainers all need to work together; even meteorologists, he says, should be part of the equation.

For Fisher and many others in the field, the message is simple: protecting athletes in this climate isn’t optional — it’s essential. Doing so takes more than a water break. It takes planning, science and a team-based approach built on communication.

“We can work around heat and humidity,” Fisher says. “We just need to start by changing the culture.”

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