Parents are paying for children younger than 10-years-old to join adult fitness clubs to get them active.
Exercise New Zealand says this is a new trend and a number of gyms are starting to offer exercise classes for children.
Chief executive Richard Beddie said there was greater awareness of the reasons why people needed to exercise, given the country's poor health statistics.
OECD figures showed New Zealand kids were the third most obese children in the world due to poor nutrition and a lack of exercise.
"Activity levels are declining and as a result we need to look at what opportunities we have to mix activity into the day. Gym isn't for everybody but if it's a way of getting kids active then it's a positive," Mr Beddie said.
A few months ago, Auckland gym Health and Sports Fitness Club started offering 45 minute cardio classes for children, aged from eight-years-old, accompanied by a parent.
The gym's group fitness manager, Gosia Salisz, teaches the classes which offer a range of exercises from pilates to squats and press-ups.
"You can run outside for an hour or you could be in a gym it really depends what they prefer. I thought we could have something that's more professional like a proper family class, which you can't really do outside," Ms Salisz said.
"I like them to learn how to do a proper press up or a proper squat, to create good habits now."
Her two children, aged 8 and 10-years-old, do the classes with her.
"I find with my kids we live on a street that's busy and I don't know the neighbours so they don't spend as much time outside as I'd like them to because I don't feel it's safe. Being outside is great, but this is more structured and it's a great way of creating habits for the future," Ms Salisz said.
Recent findings from the Dunedin Study showed New Zealand teenagers are now less physically fit and weigh more than their parents did at their age.
The study has surveyed population health for more than 40 years, and compared the fitness of more than 300 15-year-olds with results gathered from their parents at the same age.
Conscious Kids provides outdoor free-play sessions for children, and its co-founder Rita Pontes said children need to play outdoors in nature, rather than go to a gym.
"It's healthy for them but there is another way, a natural way, to get healthy," Ms Pontes said.
She said playing outdoors helps children develop holistically.
"Having good free time, at least two or three hours a day, riding a bike or going for a walk or playing is not just physical it's essential for their development."
AUT senior lecturer in exercise science, Dr Nigel Harris said offering children the opportunity to exercise at a gym is a positive move.
"While ideally we live in a world where the kids are active enough and getting the physical nourishment they need, that doesn't seem to be the case. Access to an exercise facility, if it's done appropriately, might provide a really good option for those kids," Dr Harris said.
"It isn't a silver bullet, [joining a gym] isn't the only thing they should be doing, but it represents a particularly good option and certainly the data is showing that we need to find more options for kids to move in a nourishing way."
He said research shows children need an hour of moderate activity a day, along with regular bursts of more vigourous activity.
Emma Chan takes her eight-year-old daughter Ella to the classes at Health and Sport Fitness Club, and said they both enjoy it.
"I thought it sounded like a great concept, being able to exercise with my child is a good bonding opportunity and also the chance to burn energy in a fun way and probably also the idea of starting from a younger age, instilling the habits in them of leading a healthy lifestyle," Ms Chan said.
By Amy Williams