The Olympic marathon and race walking events during Tokyo 2020 will be moved to Japan's northernmost island of Hokkaido from originally planned courses in the capital due to worries about heat, the International Olympic Committee said on Wednesday.
"Athletes' health and well-being are always at the heart of our concerns," IOC President Thomas Bach said in a statement.
"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."
Organisers had been looking for ways to protect athletes and spectators from Tokyo's sweltering temperatures expected during next year's Summer Olympics and Paralympic Games.
Tokyo held a test marathon in September, featuring tents equipped with mist machines for spectators. Officials had also been planning to hold longer-distance races during cooler hours, but questions had persisted over whether such steps were enough.
Suffocating humidity and high temperatures at the recent world championship marathon in Doha proved gruelling despite a midnight start. Nearly a third of the 70 starters failed to reach the finish line, fuelling debate over athletes' welfare.
Temperatures in Tokyo during July and August, when the city hosts the Olympic and Paralympic Games, commonly exceed 30 degrees Celsius, with high humidity adding to the discomfort.
Sapporo temperatures during the period are as much as five to six degrees centigrade cooler during the day than in Tokyo, the IOC said.
The change in location will be discussed with other parties including host city Tokyo and broadcasters, it added.