He's ran 20.5km of the Karangahake Gorge five times before, but Kelly Pender claims he's no runner.

Judging by his physical appearance alone, you'd believe him – his body shape shadows an All Black prop more than Hamish Carter.

XTerra BOP Poly students. (L-R) David Jones, Holly Leveridge, Kanta Yamamoto, Patrick Massey, Kirstie Parsons, William Dalton, (front) Neco Blank and Niki Creasy. Photo: Bruce Barnard.

'I've played rugby for as long as I can remember and I'm definitely not built for running long distances,” laughs Kelly. 'I just enjoy the off-road challenge.”

Kelly knows how to push himself. It's Kelly versus Kelly, a philosophy he encourages his Bay of Plenty Polytechnic Certificate of Fitness students to follow.

He's behind the reason why 20 students, aged 18-40, are tying their shoelaces for Blackmores XTerra Trail Challenge Waihi's 20.5km Long Course this Saturday.

'We say: ‘You versus you' within the programme and I think for them to be able to finish the XTerra Trail Challenge will make them a stronger person,” says Kelly.

'They'll take that philosophy into different aspects of their life, set the goal, do the work to achieve the goal and once you've done that, move on to the next one.”

Kelly says all but one are first-time runners in an event like this one.

'This is the 14th year I've run this programme and this is the first time anything like this has ever happened.

'They haven't done a half marathon on the flat, so to attack an off-road half marathon will make them really proud.

'It's just about getting them to the finish line. It's going to be a massive accomplishment. I'm just going along to be part of their day.”

Participants can register for the 8.2km Short Course, 13km Mid-Course, 20.5km Long Course, 43.5km Marathon or 61.5km Ultra-Marathon.

Kelly and his students will follow an estimated 980m course through tunnels, gorge, hill climbs and across swing bridges to the finish line.

So how do you prepare yourself for an event like this? 'You need a pretty good running fitness base, a little bit of craziness and a good diet,” says Kelly.

'The philosophy of our programme is to feel the fear and do it anyway. I think off road runners have a little bit of an adrenaline junkie in their blood.”

The Blackmores XTerra Trail Challenge Waihi is this Saturday, October 10.