Thermal imaging camera reveals how quickly person's body loses heat in below zero temperatures

Denver, CO - This week’s below zero temperatures did not keep a group of Denver runners from braving the chill and risking frost bite.

With temperatures around 5 degrees below zero Wednesday, the group of about 12 runners still met up for a weekly run.

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"My hands, I think, will probably be pretty cold," runner Sean Wetstine said.

To find out just how quickly a person loses heat, reporters at our sister station, 7NEWS, in Denver used a thermal imaging camera to record Wetstine's internal body heat before, during and after his run.

Before he went outside, the temperature of his face, fingers and toes were tested. His internal temperature while inside were:

  • Face: 84 degrees
  • Fingers: 81 degrees
  • Toes: 60 degrees

As soon as Wetstine walked outside to prepare for his five-mile run, his internal temperatures were measured again:

  • Face: 77 degrees
  • Fingers: 65 degrees
  • Toes: 30 degrees

During the time it took Wetstine to step outside, the temperature of the toe-area on his shoes dropped from 60 degrees to 30 degrees.

After about 15 minutes of running, his internal temperatures had significantly dropped:

  • Face: 60 degrees
  • Fingers: 45 degrees
  • Toes: -19 degrees

"OK, that explains why my toes feel cold," Wetstine said. "That's crazy. I had no idea that they were that cold."

However, by the time he finished running after 43 minutes, his body actually started to heat up:

  • Face: 73 degrees
  • Fingers: 60 degrees
  • Toes: -5 degrees

"My hands actually feel pretty good too; they're slightly cold," Wetstine said.

The outside temperature of his jacket measured 18 degrees, but when he unzipped it, the thermal imaging camera revealed his shirt underneath was 50 degrees.

Other runners didn't need the thermal imaging camera to reveal how cold they were. Wetstine's wife, Laura, ran with frosted eyelashes.

"I knew they were frozen. I could see them; they were white butterflies flashing around. Luckily your eyelashes don't feel cold," she said.

A few of the men finished with frosted beards.

"I couldn't feel my lower jaw,” runner Douglas Tisdale, Jr. said. “I couldn't really feel my upper lip. I just knew that it was freezing.”

Why do runners bear the below-zero temperatures? Tisdale summed it up like most dedicated runners would.

"Why wouldn't I? It's a perfect night for running, are you kidding me?" he said.

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