The global calendar of Olympic sports may need to be "re-engineered" amid the challenges posed by climate change after athletics' biggest stars had to contend with searing temperatures in Tokyo, World Athletics president Sebastian Coe says.
The World Athletics Championships concluded on Sunday night, following nine days of competition during which the sport's household names lit up Japan's National stadium, which four years ago hosted the Olympics behind closed doors because of the coronavirus pandemic.
The opening days of the championships were dominated by discussion around the conditions the athletes had to contend with - particularly in the endurance events - as temperatures exceeding 30C were accompanied by stifling humidity above 90%.
In addition to the quadrennial Olympic Games and biennial World Championships, World Athletics will next year stage its inaugural Ultimate Championships in Budapest to bridge the gap between its major events and provide a definitive conclusion to the 2026 season.
But Lord Coe said events such as the marathon may need to be held separately, at a different time of the year, at such competitions to protect athletes from unsafe conditions in future.
"Yes, I do see that," Coe told BBC Sport. "That's not easy because you're going even into the autumn, early winter months to cities that are still very hot.
"But I do think this is probably going to have to happen at some stage, and sooner rather than later."
According to Coe, World Athletics research has found that 70% of athletes report that climate change and the heat is impacting their training and competition programmes.
The 68-year-old said "governments haven't really stepped up to the plate" on the issue and added: "I can't see beyond the inevitability of having to collectively, as Olympic sports and probably the Olympic movement, really re-engineering what the international calendar looks like.
"From World Athletics' point of view, there will be some branding issues but I'm not sure that we can go on asking some of our endurance-based athletes to be competing at times of the year which are really are going to hit their performances and are probably putting them at risk as well.
"This has to be addressed."
Coe also confirmed that all athletes who competed in the female category at the World Championships had undergone gene testing - and that the test is here to stay.
However, he reiterated that details of any athletes who may have been prevented from competing as a result of the test, carried out via cheek swab, will remain confidential.
Its introduction comes amid reports, that between 50 and 60 athletes who went through male puberty have been finalists in the female category at global and continental track and field championships since 2000.
