Dent was forced to pull out after 70 kilometres when his body started to shut down at the Stromlo Running Festival on Saturday night.

It was the furthest the marathon runner had completed in one session in his career and he briefly contemplated walking the final 30 kilometres just to finish.

But not even being five minutes under record time could keep his legs moving as he left the course in agony after throwing up twice.

''At 50 kilometres I was five minutes under the record pace and then I started to get tired and threw up at 64 kilometres,'' Dent said.

''Then I felt pretty ordinary. By 68 kilometres I was walking, then I threw up again and called it a day.

''I don't know why or what happened, nutrition or training … my body just couldn't cope with the later-on stages but I definitely don't regret having a crack.

''I just couldn't face walking 30 kilometres at the end though … even jogging slowly was difficult because my entire lower body was in an ordinary state.''

Dent's torture test was one of several events at the fifth Stromlo Running Festival.

Athletes flocked to the venue for primary and high school races, 100 and 50 km events and the Lightning Strike 30 km races at the weekend.

Indigenous Marathon Project runner Emma Cameron used the 30 km race as a selection test for the Boston Marathon and the Darwin athlete was successful in her bid to win a spot.

Running festival organiser and marathon legend Robert de Castella said: ''It was a huge success this weekend, numbers in the Lightning Strike doubled from last year.

''Everyone just loves running through the trails with fantastic views coming over the hills.''

Dent will switch his attention to the impending birth of his fourth child in April.

He will then travel to New York with some of his Department of Industry, Innovation, Science, Research and Tertiary Education colleagues for the international final of a corporate challenge in May.

The 34-year-old also holds hope of gaining selection for the world championships in Moscow, but has to wait until May for Athletics Australia to select the team.