A mountain race on Lord Howe Island took a dramatic twist when Ollie Whistler collapsed 50 metres before the finish but recovered to beat his father's long-standing record with just seconds to spare.

This morning five contestants set off on the Mt Gower Challenge, a new and dangerous race to the top of an extinct volcano and back again on tourist popular Lord Howe Island, 600 kilometres east of New South Wales.

Runners had to race along sheer cliffs on the trek to Mount Gower. ( Supplied )

In 1995, pro marathon runner Phil Whistler set an official record of 1 hour 41 minutes 10 seconds for the 13-kilometre track that takes contestants along sandy shores, sheer cliffs and through a lush and dense rainforest at the peak of Mount Gower.

Today's challenge was a family affair with 62-year-old Phil Whistler competing along with his wife Michelle and son Ollie, as well as 17-year-old Kayla Hiscox and her father Dean Hiscox, a local tour guide.

A crowd of about 100 locals and tourists were watching on as the staged time trial began at 9am (AEDT).

Pro runner Ollie Whistler, 27, had the pressure of keeping the men's record in the family name.

His friend and fellow professional Australian runner Tim Reed had been expected to compete but could not get to the remote island after his flight was cancelled. Dean Hiscox took his place.

Ollie collapses short of finish

Disaster almost struck on the race back down the mountain and along the shore towards the finish at Capella Lodge.

Ollie Whistler was on antibiotics after recently coming down with a virus.

About 20 minutes out from the finish line Ollie says he was delusional.

"I don't even remember much of it," he said.

Phil Whistler arrives at the finish line near Capella Lodge. ( Supplied: Jack Shick Photography )

He looked at his watch and misread the time, thinking he would miss his father's record by about 20 to 30 minutes.

His body gave way and he collapsed just 50 metres out from the finish line at the bottom of a hill.

Unknown to him, he was on track to narrowly beat the record.

With the seconds counting down, he was helped up and managed to take himself over the finish line in 1:40:23, securing the record with just 47 seconds to spare.

Local doctor Frank Reed, Tim Reed's father, placed Ollie on a drip and treated him at the scene.

When he came to Ollie was greeted with the news that he held the new record.

"Someone told me. I just couldn't believe that that was possible," he said.

"I've never hurt so much in an event in my life."

Ollie says he thought he had been in a better state than he was leading into the race.

"If Tim had been here today, he would've been faster than me," he said.

"I know that the record can be broken."

Michelle Whistler set the first official women's record for the 13km race. ( Supplied: Jack Shick Photography )

Meanwhile, Phil Whistler was happy to have his son take over the reins and completed the race in 2:07:46.

In the women's event, Michelle Whistler set the first official time of 2:30:54.

Kayla Hiscox gave the gruelling challenge her best but did not finish the race. Her father, Dean, also pulled out.

The race and community events such as breakfast and live music raised money for the local island school.

Ollie says he would love for the race to become and annual or biannual event.

"It really brings the community together and brings the visitors in as part of our community," he said.

"It'd be great for tourism over here if we can make it an annual event."