【Philippines adult】

No wheelchair user has ever been allowed on Philippines adultAustralia's Larapinta trail -- until now.

This week, Dr William Tan, a Singapore Paralympian, begins a five day journey across 65km (40 miles) of the Australian outback.

The 60-year-old has in the past completed marathons across Antarctica and the North Pole, but says the upcoming challenge will be the "most treacherous one" yet.

The terrain in the Larapinta Trail is rugged and steep, making it difficult even for the average athlete to complete -- much less someone crossing it in a wheelchair.

"The terrain is so rough, so undulating...with rocks, gravel, pebbles," said Dr Tan, who spoke to Mashable before embarking on the challenge.

"This will be the most treacherous trail I've ever embarked on."

The Larapinta Trail, located in Australia's Northern Territory, also cuts across many Aboriginal sacred sites that are not accessible to wheelchair users.

However, an exception is being made this time since the challenge is for a good cause, said Dr Tan, who contracted polio and became paralysed from the waist down at the age of two.

Dr Tan will be completing the challenge alongside others as a fundraising activity for the University of Newcastle in Australia, which aims to raise some S$108,000 towards supporting indigenous education and healthcare.

'An armoured tank'

So how will he be preparing for it?

For one, he's modifying his wheelchair to take on the rough terrain.

"This isn't your normal day-to-day wheelchair. The front wheels have been modified to make it bigger and thicker. [If you have small wheels] they can get stuck in the crevices between rocks," he says.

"This [wheelchair] is almost like an armoured tank that goes over any terrain."

His back wheels have also been modified -- the wheels measure 26 inches, bigger than the average wheelchair, and has a more rugged grip.

But it's not only his wheelchair that is gearing up for the trail.

"I train twice a day, every day. Early in the morning before coming to work and in the evening no matter how late," he says.

"Weight training is very much a part of my routine [because when I'm on a wheelchair] I have to grip on the tyres and push on it to have power [to move ahead]. Especially on uneven terrain, you have to push the wheelchair on just the two back wheels so you can overcome the obstacles."

Dr Tan demonstrates:

But there are also the unseen obstacles that Dr Tan has to prepare for.

For instance, he's brought six spare tyres and a pump, just in case of a flat tyre -- something a walking participant wouldn't even have to think about.

He's also bringing ropes, which he might need in the scenario that he can't wheel himself across an obstacle.

"My biggest challenge will be places that are rocky and yet inclined [because] in such an event [I might] be gliding backwards," he said.

"So I might have to ask for help and ask other participants to pull me up with ropes. I know my limitations...and to be realistic, I'm not there as a hero."

Yet Dr Tan remains positive that he will complete the course.

"There's a saying, 'When there's a will, there's a way', and my name is Will," he laughs.