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HEALTH | Tokyo Olympics

Strange science: Tokyo 2020 marathoners should 'keep right'

Caroline Floyd

Sunday, August 5, 2018, 7:01 PM - Researchers in Japan are planning ahead for the 2020 Summer Olympics, and they've come up with an unusual bit of advice for those attempting to conquer the marathon: Keep right to keep cool.

The games, to be held in Tokyo, will take place during the hottest part of the year in the city -- late July and early August, when the average daily high temperature is 30ºC. In fact, this weekend's high temperatures and humidity have humidex values in the upper 40s in the city; something that's not unusual in Tokyo's early August. Nor, indeed, has it been unusual across all of Japan this summer, which has seen the number of Japanese residents hospitalized due to heat illness climb into the tens of thousands.

As many Canadians have also experienced firsthand this summer, the risk for heat-related illness increases tremendously when the humidex edges into the 40s. With marathons right near the front of the pack of sports with a high heat load for athletes, it'll be particularly important for runners to try to mitigate the effects of the potentially oppressive air temperature.

(Related: High humidity spurs heat risk - Recognize these heat illness signs)

Fortunately a team led by a researcher at Chiba University is on the case.

The team analyzed readings of temperature and humidity from along the route, collected in early August 2014 by Tokyo's high-resolution observation network. Contrary to what the old song says, it turns out runners shouldn't direct their feet to the sunny side of the street; at least, not if they want to avoid heat stroke.

According to the study, the right-hand side of the street on the outbound leg of the 42 km route, and the left-hand side of the inbound return, ran significantly cooler than the opposite side of the road. The cause? Shadows cast by high rise buildings lining the streets. Researchers found that staying in the shade made up to an 8ºC difference in apparent temperature.

(Related: Why we're hard-wired to ignore heat safety warnings)

Tokyo's tall buildings may provide much-needed shade to distance runners at the 2020 Olympics. Tokyo aerial view from Roppongi Hills. Views toward Koto, Minato, Chuo and Tokyo Bay. Image: Getty Images

"Passing the right side (left side in the case of return) of the course could keep the accumulated value [of heat load on a runner] slightly lower along the course in the morning because the marathon course roughly runs from west to east and buildings’ shadow is on the relatively right side (south side)," reads the paper's abstract, calling making a shadow a "relatively effective cooling method."

The team also looked into what time of day would be best for the race, using data collected between 2007 and 2016. They concluded the risk of heat illness rose rapidly after 8 a.m., saying it was safest if the race finished before 9 a.m., or started after 7 p.m. local time.

If 2020 Olympic dreams are part of your training goals, you might want to keep this information in your back pocket, but don't use it to plan your entire race. The research team also added that, practically speaking when added up over the length of the course, "the effect of changing the position on the course was small." Still, every little bit helps when you're going for the gold.


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