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Scientists nail the coolest course for marathoners at the 2020 Olympics

The 2020 Summer Olympics in Tokyo are still years away, but scientists already have some advice for marathon runners who will be running for the gold: Stay right if you want to stay cool.

The games will be held in August, the hottest time of the year, so heat could pose a major threat to athletes—especially marathoners, who face a higher risk of heat stroke than most competitors. To help reduce that risk, researchers used existing temperature and humidity data to forecast thermal conditions along the expected marathon course in Tokyo, as well as how shadows from adjacent buildings might fall across the 42-kilometer route.

The modeling indicates that runners will stay slightly cooler if they stick to the right side of the course on the outgoing leg, and the left side when returning, the researchers report this month in the International Journal of Biometeorology. The study suggests temperatures could be 26°C to 28°C when the race starts and climb gradually over the next few hours.

Staying on the cooler side of the course could reduce the warmth experienced by runners as much as 8°C, the researchers estimate. The same methods, they note, could also be used to study the potential heat risks posed by other Olympic events that will be held outdoors, like track and field and beach volleyball.