Are Older Women Runners at a Disadvantage in the Heat?

Study finds they store more body heat than younger women when exercising in hot weather.

Thursday, May 30, 2013, 12:00 am
Image by Ian Kim

Older women don't dissipate body heat when exercising in hot weather as well as younger women of similar fitness, according to a study that will be published in Medicine & Science in Sports & Exercise.

The study's findings suggest that, because they store more body heat during hot-weather exercise, older women might see their performance decline more than younger women. More stored body heat should lead to a higher core temperature and a higher heart rate at a given pace, both of which eventually diminish performance.


For the study, Canadian researchers gathered 11 younger women (average age of 24) and 13 older women (average age of 51) who had similar aerobic fitness, body composition and body surface area. (More surface area allows for more evaporative cooling, so it was important for the study that the women be matched in this regard.) The women did four 15-minute bouts of cycling at a fixed work load, with 15 minutes rest between, in conditions of 95 degrees Fahrenheit and 20% relative humidity.

The recovery periods were part of the study because the researchers wanted to measure heat-coping mechanisms both while the women worked out, and while they rested. The researchers reported:

"At the end of the 2-hour intermittent exercise, the older females had a greater cumulative change in body heat content which was paralleled by a greater change in core temperature. This was a consequence of a marked reduction in their ability to dissipate heat only during exercise given that both the young and older females showed a similar attenuated rate of whole-body heat loss during the post-exercise recovery periods."

The researchers found that the older women's reduced ability to dissipate body heat was evident as soon as 10 minutes into the exercise. As such, they note, their findings suggest that older women exercisers should be especially careful about avoiding heat-related injury.

The video belows offers some general tips for running well in the heat.