"What is life without risk and adventure?" asks one of the young men who features in a video showing free-runners scaling scaffolding and leaping from rooftops at a Northland school.

But not everyone is impressed with the antics in the video posted online, with a Whangarei principal concerned unskilled copycats will get in on the act.

Part of the video, which the four participants posted online, is filmed at Hora Hora School and principal Pat Newman said the acrobatics - which included flips, high-speed leap frogging and bounding between rooftops - caused minor damage to school buildings. This was denied by the group involved, who said they carefully checked they had left no trace.

"But my big concern is the safety," Mr Newman said. "I don't want to have to turn up to school and pick up the smashed bones off the concrete ... I thought hells bells that's skilful, but doing it off the roof of a school is cuckoo mad. I also don't want all the kids in town trying to emulate them."


Mr Newman said he had sent the video to police and hoped officers would speak with the young men about it.

The boys were practising parkour, an acrobatic way of overcoming obstacles, usually in the urban environment.

Twenty-seven-year-old Frederick William Mackie was in the video and had taught the teenage boys who featured.

Mr Mackie was a recognised athlete through New Zealand Parkour, had a degree in health and fitness and was a qualified personal trainer.

"Indeed the fear is always there, it's always present even right up to the point of jumping or flipping," he said.

"But [the] truth is that it's all a mental thing, so I teach people how to get past it and it's the same as in everyday life ... We can use all the bad things to do good."

He said the key to staying safe was controlling emotion and the surroundings as much as possible. He said he checked that no damage was done to the school.

Mr Mackie said while others would indeed try the sport, it was best to get formal training and he had never come across anyone who "did it out of stupidity".

"I don't encourage it nor do I appreciate or approve of people getting hurt ... Hence why I train them and teach them so those things don't happen," he said.

"It seems life threatening, even stupid to most, but what is life without risk and adventure?"

New Zealand Parkour chief executive Damien Puddle said most of what was shown in the video was good practice, but he did not support jumping on corrugated iron rooftops.

"Parkour is becoming more and more popular every year and we're working to try and ensure issues like this don't happen."

Mr Puddle was working on a PhD examining the development of parkour in New Zealand and said his organisation had been set up to connect people with the core philosophies of parkour, which included "leave no trace".