The heat rule should move the race, not the runners

Relocating a marathon a thousand kilometres north solved one Games and dodged the decision the sport keeps refusing to make.

Wet-bulb globe temperature is the number that matters and almost nobody outside sports medicine has heard of it. It folds air temperature, humidity, radiant heat and wind into a single figure that predicts whether a body can shed the heat it is producing. Above a threshold, sweating stops working well enough, core temperature climbs, and the failure is not gradual. Runners go from uncomfortable to collapsed in a few minutes.

Endurance events at a summer Games sit close to that threshold in most cities that can afford to host one.

The responses so far have been improvised. Start the marathon at six in the morning, or five. Move the race walk. Move the whole event to a cooler city hundreds of kilometres away, which was done once, at enormous cost and considerable insult to the host, and which worked. Every one of these is a patch applied late, after the venue contracts are signed and the sponsors have paid for a skyline.

The obvious fix is the one nobody will say inside a bid evaluation meeting. Stop awarding summer Games to cities that cannot hold a marathon in July, and stop pretending a six a.m. start makes the problem disappear. A dawn race in a humid coastal city can still exceed the threshold, and it produces a spectacle nobody sees, run past empty barriers, which quietly undermines the argument that the marathon is the great civic showpiece of the Games.

There is a second option and it deserves more respect than it gets. Move the Games. Not the city, the date. The northern summer is a broadcast convention, not a law. A September or October Games opens up hosts that are currently impossible and takes the endurance events out of the worst window. The reason it does not happen is that it collides with the domestic football and American sports calendars.

So the sport chooses. Heat risk for the athletes, or a scheduling fight with leagues that have more money.

It has chosen the athletes' problem every time so far, and dressed the choice up as a start-time adjustment.