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HHP Faculty Dr. McFarlin Featured in The Houston Chronicle.

HHP's Dr. Brian McFarlin was featured extensively in a Houston Chronicle article on a new study which claimed that men who exercised 40 minutes on a treadmill in hot conditions — temperatures above 97 degrees — ate far less at their next meal than those who exercised in climate-controlled conditions. Dr. McFarlin cautioned against exercising in the heat to lose weight.

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Dr. Brian McFarlin

Below is an excerpt from the article:

A person at rest at room temperature has myriad ways to keep cool. The skin, with a temperature of about 91 degrees, transfers heat into the surrounding air. The body, with a temperature of 98.6 degrees, radiates heat. And cooler air flowing over the skin carries heat away.

When air temperatures rise into the upper 90s, said McFarlin, these cooling processes reverse and begin to heat the body.

At that point all the body can do to cool off is sweat. And because of Houston's typically high humidity, sweat's evaporation-cooling process is less efficient at cooling the body.

The body makes sweat by pulling fluid from blood. This, in turn, causes the blood to thicken and the body to literally begin to dry out.

The first stages of dehydration are cramps and then heat exhaustion, when sweat is increased.

Finally the body can sweat no longer, bringing on heatstroke, which requires immediate medical attention to stave off brain damage, organ failure or even death.

“For most people, the risks of working out in the heat and humidity just aren't worth it,” McFarlin said.

That's not to say there aren't benefits. Because the body is so taxed in trying to cope with heat, it burns more calories exercising at 97 degrees than it does at 77 degrees, he said.

Read the entire article on the chronicle website (pdf version)