How athletes and spectators can avoid suffering adverse health effects in Tokyo's blazing summer heat remains one of the major challenges 2020 Olympic and Paralympic Games organizers are facing.

As Tokyo suffers through yet another sweltering summer, with the mercury hitting as high as 35 C in mid-August, the games' organizing committee and athletes are taking the pre-Olympic test events as a golden opportunity to understand what to expect next year.

At the triathlon test event earlier this month, athletes battled the heat by making strategic changes to their competition plan as well as taking precautionary measures ahead of the race, including wearing ice vests and shortening warm-ups.

The temperature was 29.5 C at Odaiba Marine Park, the venue of the 2020 triathlon events, at 7 a.m. on Sunday, Aug. 18 an hour before the start of the mixed relay race, a new medal event added to the Olympic program for 2020. The mercury shot up to about 35 C toward the end of the test event.

"I think (the heat) is very hard, but we all prepared very well for this," said Brazil's Luisa Baptista. "I think next year we'll try new methods (to battle the heat)."

While finishing only 12th in the 22-team race won by the French, Baptista said competing in Tokyo a year out had great significance as it will allow her team to analyze the outcome and come up with better countermeasures.

Event organizers made announcements via loudspeaker urging spectators to be cautious of heatstroke. An ambulance also stood by in case of an emergency, while 10 staff walked around the spectator seating area to attend to fans who might be feeling unwell.

During the race, bottles of water and ice packs were handed to athletes at designated spots on the run leg, which also had mist sprayers to give some brief respite. Many athletes poured water on their heads and pressed ice packs to their necks and armpits.

After France's Dorian Coninx and Britain's Alex Yee broke through the finishing tape almost simultaneously, they both crumpled to the ground as their teammates doused them with cold water and dragged them into the shade.

While the International Triathlon Union took several countermeasures to deal with the heat during the four-day test event, it was forced to make changes to the event program, including switching starting times and shortening the running segment in one of the races.

Athletes who competed on Sunday said preparation meant everything when it comes to racing in Tokyo's summer heat, including camping in Japan or other hot places.

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"I know everybody has their own heat protocols. People were sitting in saunas and intense heat. I was training in Arizona where it's really hot," said Ben Kanute of the United States.

The athletes, however, are not the only ones who will need to be prepared for the heat.

Volunteers and spectators, who filled the stands on Sunday, were also trying everything they can to stay cool.

Some spectators held portable electric fans and drank from large bottles of water. As the temperature increased, many people took refuge in the shade or under a large mist sprayer installed by the Tokyo metropolitan government, partly because the stands were not covered.

"It's way too hot. I can't stand the heat unless I take shelter," said Masafumi Kishi, who came to the venue with his two children, aged five and six. "It has been difficult for the kids too. I wonder what it will be like next year."

Pre-Olympic and Paralympic test events are held for organizers to check and drill operations, while in some cases giving athletes a chance to get accustomed to the venue. This summer's tests, however, have ended up raising questions and concerns.

While the International Olympic Committee has praised Tokyo's preparations, the problem surrounding the weather is still a work in progress. The issue has been the center of attention at test events as heat-related illnesses again claimed many lives this year in Japan.

The capital hosted its first Summer Games in the much-cooler month of October in 1964, but next year's Olympics, featuring 33 sports and 339 events, will run between July 24 and Aug. 9. The Paralympics will take place from Aug. 25 to Sept. 6, a period expected to be a little less sweltering.

The IOC also created a leaflet for athletes introducing 10 tips to "beat the heat" during the Tokyo Games. The advice includes getting acclimated to the heat by training in similar temperatures for at least two weeks, implementing a hydration plan starting in the days preceding the event and wearing a hat and sunglasses.

Earlier this month, some athletes suffered symptoms of heatstroke at the rowing test event at Sea Forest Waterway, the Olympic rowing venue. At an equestrian test event, athletes called for earlier morning start times since the heat poses a threat both to them and the horses.

Last week, the running segment of the women's triathlon event was halved from 10 to 5 kilometers due to the heat and humidity, making national and international headlines.

And two days later, the swim leg of the Paralympic triathlon event was canceled after organizers found that the amount of E. coli bacteria in the water at the venue was more than two times higher than the maximum limit set by the ITU.

Water quality at Odaiba Marine Park, a waterway located very close to central Tokyo, has been a big challenge for 2020 organizers.

While triathletes who took to the waters said they did not experience a problem, open water swimmers -- athletes that spend a lot longer in the water -- said they were put off by the bad smell of the water when competing in a test event earlier in the month.

Representatives of the ITU and the Japan Triathlon Union suggested changes in the Olympic schedule to work around the weather and the condition of the venue.

Yasuo Mori, the deputy executive director of the games operations bureau, said the organizing committee would make the most of what happened during the test events to come up with a plan for next summer.

"A lot of things happened during the test events, but we will analyze data while taking into consideration the comments and ideas from concerned bodies. We will go through things one by one," he said.

"Offering an environment where athletes can compete at ease and in safe conditions is, obviously, the most important thing," he said, while ruling out the possibility of moving the Olympic triathlon venue at this late stage.

Test events for the 2020 Games are scheduled to take place until May.