An Olympian has inspired a group of primary school children to run a full 42km marathon - a kilometre or two at a time.

Up to 65 pupils from Bayfield Primary School in Herne Bay will run the last 2.2km of their race in tomorrow's adidas Auckland City Marathon, to complete an exercise programme created by Rod Dixon.

The 1500m bronze medallist at the 1972 Munich Games won the Auckland Marathon in 1982 and the New York Marathon a year later.

In the past 12 weeks, the Bayfield youngsters have run 40km with their teachers and parents.

One of them, 10-year-old Lucia Taylor, said the last 2.2km should be "pretty easy" after all her training.

Lucia will be one of 14,500 competitors expected by race organisers for the marathon.

Runners will tackle either the 42km marathon, a half marathon, a quarter marathon, a 5km fun run or walk and the kids' marathon, where young entrants will cover 2.2km.

The youngest entrant is Bradley Moody, 7, in the kids' marathon and the oldest is Mary Milcich, 82, who is set to walk the 5km event with her husband Ron, who is 81.

The oldest person entered in the full-marathon category is Gordon Jackson, 75.

Aucklander Geoff Nottage, 32, will compete in his sixth Auckland Marathon dressed as Darth Vader.

The idea to run dressed in costume originally came when he and a few mates were having a beer after touch rugby about seven years ago.

This year, he will be running with a friend, who will also dress to the Star Wars theme as a storm trooper.

"It's just a bit of fun really. We always have water fights at the drink stops, and attack each other with light sabres. How else do you pass four hours?"

Running in costume provided a unique set of challenges, Mr Nottage said.

"It just gets so hot and you can't see in it. I think I'm the only person who hopes for wind and rain, but it's never bad weather and it's not going to be this weekend either."

He said this race would be his last in a Vader suit.

"I figure that there were six episodes in the Star Wars series and as Darth dies in the last movie it would be a good time to call it quits and retire the costume."

In 1992, the marathon became the first event to include the Auckland Harbour Bridge as part of the course.

The run over the bridge is now a drawcard for those who relish the chance to experience the Auckland landmark by foot.

A spokesman for the organisers, Scott Newman, said planning the event was now a year-round job, involving 10 fulltime staff.

"It certainly seems that exercise, and appreciating the outdoors, is something that has become more and more ingrained in New Zealand's culture over time.

"People enjoy the day because it has a festive atmosphere ... From 8am, supporters and runners begin to gather at Victoria Park for the picnic in the park, which is kind of like a post-race party."

The event includes live music, games, prizes and food for runners, friends, families and supporters.

Marathon logistics
* 45,000 litres of water at the aid stations.

* 116,000 paper cups.

* 15,700 bananas.

* 3500 road cones on the course.

* 750 volunteers.

* 37 countries will be represented.