Days later he saw 30 athletes in the men's Olympic Games marathon fail to complete the 42 kilometre run in Tokyo's sweltering heat and humidity.

That's why, after Roeger watched the bulk of Australia's Paralympic Games athletics team leave camp for the airport, he walked outside in Cairns' blazing sun in the middle of the day, and ran.

The 33-year-old is bound for his fourth Paralympic Games appearance and he is leaving no stone unturned to ensure he is ready to cope with the conditions in Tokyo.

Roeger is one of a few athletes left at the Australian team's Cairns base, and he will be the last athlete to arrive at the athlete's village on September 1.

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His tilt for Paralympic gold in the T46 marathon on September 5 doubles as the final event of the Tokyo Games.

His last long training run behind him, Roeger is now inside the final fortnight of his preparation. He has knocked off 160-175 kilometres per week for an eternity, now it's about "freshening the legs, freshening the body, freshening the mind" for the enormous task ahead.

"It's funny, it is a rollercoaster journey. I've had a couple of niggles over the past month but, one of my mentors said this, there is no such thing as a perfect prep and this one is no different," Roeger said.

"We're covering all bases. We've done a lot of heat work, we've come up to Cairns five weeks before the marathon.

"We've watched the Olympic Games, we've watched the Olympic men's and women's marathon, we've got ideas around the heat and how to deal with it, the drink stations, the strategies.

"It was good watching the Olympics and seeing that. I think we're prepared for the heat and the warm weather when we get there.

"We're expecting it to be high 20s. At 6.50am, the marathon kicks off. They think about 27 to 30 degrees with about 70 per cent humidity.

"One good thing is we won't have the direct sunlight in the first 90 minutes of the race so that will be a big help. I've been training in the middle of the day in Cairns in the direct sunlight, and the heat, so it has been pretty warm."

Because the conditions Roeger faces in Tokyo are set to be unlike anything else he has competed in.

Much like their Olympic counterparts, for months Australia's Paralympic athletes have been acclimatising in preparation for Tokyo - be that in heat chambers at the AIS or in training camps in Queensland's heat.

"That's why I'm trying to cover all bases and talk to as many people as I can," Roeger said.

"As you saw Pat Tiernan in the men's 10,000m on the track, he was collapsing. At the Gold Coast Comm Games in 2018, we saw Michael Shelley come home over the Scot, he collapsed in heat.

"The big thing is with the heat, as my coach Philo Saunders says, you've just got to make sure you're running within yourself and don't tip it over too early, because once you tip it over and get that heart rate up, it's pretty much impossible to get it back down.

"You've got to run to your strengths and have a strategy, and don't go out too hard."

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