The marathon and race walk events at next year's Olympics in Japan have been moved from Tokyo.
They'll now be held 800-kilometers further north in Sapporo - where the temperature is cooler.
Olympic Committee president Thomas Bach says athlete safety is at "the heart of the decision".
“Athletes’ health and well-being are always at the heart of our concerns. A range of measures to protect the athletes have already been announced.
"The new far-reaching proposals to move the marathon and race walking events show how seriously we take such concerns.
"The Olympic Games are the platform where athletes can give ‘once-in-a-lifetime’ performances, and these measures ensure they have the conditions to give their best.
"I would like to thank World Athletics, and we look forward to working with them on the implementation.”
Almost half the field failed to complete the women's marathon at the recent World Athletics Championships in Doha due to the heat.
International Association of Athletics Federations president Seb Coe has welcomed the IOC's decision.
"Giving athletes the best platform for their performances within the environment they are in is central to all major events, and we will work with the organisers to create the very best marathon and race walk courses for next year's Olympic Games.
