At the 2019 world track and field championships in the muggy heat of Qatar, a total of 108 marathoners and racewalkers swallowed wireless temperature pills a few hours before their races and posed for an infrared camera at the start and finish lines. The resulting data, some of which has just been published in the Journal of Applied Physiology, offers a peek inside the engines of the top athletes in the world in real-world competitive conditions—including some unexpected surprises.
The unsurprising part is that the athletes got very hot. The conditions for the events included in the study—marathon, 20K racewalk, and 50K racewalk—ranged between 85 and 91 degrees Fahrenheit, with relative humidity between 46 and 81 percent. And this was in the middle of the night! The races took place between 11:30 P.M. and 5:00 A.M. local time, which at least eliminated the additional heating effects of solar radiation, both from above and reflected from the road.
Still, it was much too hot for optimal performance. Only one of the athletes in the study matched their pre-event personal best, and on average they were 13 percent…
