Paul Grinvalds has completed 114 marathons in all 50 states, but he still wilts when he races in temperatures beyond 60 degrees Fahrenheit (15. 5 Celsius). “One thing about marathoners is typically we're kind of stubborn,” said Grinvalds, 68, from West Des Moines, Iowa, who finds even temperatu...
Source: [Yahoo Sports](https://sports.yahoo.com/articles/warming-climate-forcing-marathons-consider-130145172.html)