Iowa marathoner says heat makes racing painful despite 114 finishes

Body cannot cool itself during sustained exertion

Paul Grinvalds has completed 114 marathons across all 50 states. But the 68-year-old from West Des Moines, Iowa, said he still wilts when he races in temperatures above 60 degrees Fahrenheit (15.5 Celsius).

“One thing about marathoners is typically we’re kind of stubborn,” Grinvalds said. “So if we have a goal and it’s hot, a lot of times we’re still going to try to do that goal, which is just stupid because you’re almost guaranteed to have a very painful experience.”

Most runners face the same vulnerability because the body cannot cool itself during sustained exertion. Heat compounds the difficulty, and Grinvalds said even temperatures in the 50s F (10 C) feel warm for racing.