It was a steamy 31 C with 75-per-cent humidity when Evan Dunfee stepped up to the starting line at midnight for the 50-kilometre race walk at the 2019 world championships in Doha.

The sizzling conditions weren't conducive to fast performances in the long-distance event, but like a trio of mad scientists, Dunfee, his coach Gerry Dragomir and sport physiologist Trent Stellingwerff had carefully prepared for competing in this virtual sauna for years.

With a perfect recipe of talent, training, strategy and science, Dunfee finished third.

"I'm really proud of that bronze and kudos to Evan and his coach Gerry for just being so open to sport science," Stellingwerff said.

Long before COVID-19 became the biggest threat to the Tokyo Olympics, the top concern was the heat. Last summer, the temperature soared to 41.1 C in Japan, matching a record for highest temperature in the country set two years earlier.

Tokyo is expected to be one of the hottest Olympics on record, and recent heat waves have had organizers bracing for the worst.

Daily maximum temperatures during Tokyo summers average about 30 C, with 80 per cent humidity, but forecasts say there's a chance of consecutive days at 35 C or even hotter.

The conditions will prove even tougher for teams arriving from cooler climates with no chance to acclimatize, as COVID-19 restrictions have meant shorter stays in Japan.

As Dunfee's race in Doha showed, how the body reacts to heat can be the difference between climbing the medal podium or finishing well back. Or not finishing at all.

The 30-year-old from Richmond, B.C., paced his race perfectly, sitting well back of the leaders through most of the race.

"It was so obvious, the lack of preparation the other athletes did, even before the race, the lack of athletes doing pre-cooling," Dunfee said. "And then out on the course, I think I poured over 100 litres of water over me. And I'm seeing other athletes who weren't doing any of that, and a lot of athletes who were dropping out at a pace that was pedestrian."

Dunfee worked his way through the pack, and more than 70 times over the course of the race, he grabbed something -- either a bottle of water, an ice-filled hat, or a stocking of ice to wrap around his neck -- at an aid station.

With 10K to go, he was still well back of the leader, but feeling comfortable.

"But everyone in front of him had overdone it and they were coming back to him," Stellingwerff said. "He worked his way into bronze literally in the last kilometre. And he was two seconds out of silver."

The work Dunfee and his team had done included studying his core body temperature through the use of high-tech, computerized pills. Dunfee knows at what temperature his body starts to break down, and the paces he can push before he gets to that point. He knows the tricks, like pre-race ice tubs and ice vests, to help him keep his body temperature down.

Stellingwerff and other sport scientists have done hours of similar work with other Canadian athletes to prepare them for the Tokyo heat and humidity.

Concerns about the heat saw Tokyo organizers move the marathons and race walk events to the northern city of Sapporo, but even on a hot day in Sapporo, Stellingwerff said he wouldn't be surprised to see marathoners run 10 to 15 per cent slower than their personal best times.

The heat also affects events of shorter duration. Wendy Pethick works alongside Stellingwerff at the Canadian Sport Institute Pacific in Victoria, focusing a good chunk of her time on Canada's rowing team.

She said a six-minute rowing race, because it's at maximal effort, can see the core body temperature soar from the normal 37 C to 40 C. She had one athlete compete at 42 C, but "that is very extreme and he suffered for a number of days afterward."

Rising body temperature steals energy that should be concentrated on the performance.

"When you're working at those maximal levels, you have maximal cardiac output and its job is to fuel the muscles, but it now also has to try to cool the body," Pethick explained. "In cooler temperatures, more of that cardiac output can just be focused on fuelling the muscles, whereas (in heat and humidity) you've got a couple jobs to do now. So that's one of the reasons it has such a big impact, is that trying to cool the body takes a lot of energy."

Pethick said the heat wave in B.C., then a staging camp for the rowing team in Sagamihara, Japan, provided the perfect conditions for acclimatizing.

The science around heat has improved dramatically in the past couple of decades. Mike Van Tighem, the distance coach for track and field in Tokyo, recalled the 1994 Francophone Games in Paris. Canada's Isabelle Dittberner won bronze in the marathon in 35 C heat, and "I was literally holding her up during the award ceremony," Van Tighem said.

"Then she went and had two IVs and was fine. I might be oversimplifying but our preparation was kind of like: she's going to take water and Gatorade at the aid stations. And there was no staff at the aid stations. It was just like your normal community marathon kind of thing. There's some tables, and 'good luck!'

"We've come a long way."

Among Van Tighem's athletes in Tokyo will be marathoner Malindi Elmore, who's been training in temperatures in the high 30s in her hometown in Kelowna, B.C. Van Tighem said he's done careful monitoring with the Canadian record-holder on everything from carbohydrates consumed before long runs to weight lost during.

Canada's Damian Warner, the world No. 1-ranked decathlete, and coach Gar Leyshon have been tinkering with cooling techniques such as wearing ice vests.

"The two events that are the problem are the high jump and the pole vault, because you're out there (in the stadium) forever, right?" Leyshon said. "Sometimes it can take two hours, and you're outside in the heat, in the sun, in the middle of the day. But we're going to have cooling vests and a cooler full of ice water and towels to put on. . . we're certainly aware of (the heat concerns)."

Tokyo presents unique challenges due to COVID-19. Teams normally travel with their own ice tubs, but that won't be permitted this time. Pethick said she understands that athletes will get one bag of ice per day, and she's packed muffin tins to freeze her own.

Travel restrictions around COVID-19 have prevented athletes from training in humid locations. Athletes have trained in the CSI Pacific's erg dome, which is like a tennis bubble, but it's difficult to make it humid without the temperature dropping inside, Pethick said. There's also an environmental chamber in which athletes can either train on a treadmill or exercise bike, but it can only hold two athletes at a time.

"The humidity has a massive impact, so we've been cycling the various groups (of athletes) through there," Pethick said.

Tokyo hosted the 1964 Olympics in October to avoid the hottest months, but that was before the increased demands of sponsors and broadcasters who don't want the Games battling with the NFL, NBA and NHL for viewers.

Meanwhile, Dunfee is hoping for an uncharacteristically hot day in Sapporo, where race walkers will have to deal with direct sunlight after running in the middle of the night in Doha.

"That'd be ideal," he said. "I've consistently proven that I perform well in heat. I think I'm fit enough to battle with the guys no matter what the conditions are, but certainly I'll have a little smile on my face it it's going to be a hot day."

This report by The Canadian Press was first published July 18, 2021.