Zack Emmett is awaiting verification from the Guinness World Records whether his 2300 sit ups is the most by a child under 10.

"Well, it wasn't that easy, but it wasn't really, really hard," Zack said of the attempt.

Zack's grandparents Jan and Noel Chapman read about a nine-year-old from Melbourne in Nate Long who got bored during COVID-19 lockdown and broke the mark of 2200 sit ups, which is believed to be an unofficial world record.

While Brazilian man Edmar Freitas holds the world record with 133,986 in 30 hours, there isn't a category for sit ups for those under 10.

Generally, you contact Guinness World Records first and it approves the attempt, so you then set about creating the record.

"I said you can't do 2300 sit ups without doing a little bit of training," dad Rod said.

"Anyway, he wanted to do it before he was 10 (August 19), and he said if I start at 500 and increase by a couple of hundred every week, he'll be able to have a got at it before then, but he decided to have a go at it after two weeks (laughs).

"He decided to do it over one afternoon, he was going to go for a bike ride, and then thought, 'oh no, I'll do that instead and off he went'.

"It took him around one hour and 40 minutes without stopping, it's a huge effort.

"He's a little goer, he's got a lot of self-motivation."

Zack loves his sport, combining rugby league for Albury Thunder, weekly boxing sessions with his dad and cousins, along with running.

He's used to setting himself a challenge in all his interests and even moreso as a halfback in league.

"I like using my head to figure out where to go and I like scoring tries, like everyone does," he said.

"I just think it (fitness) is really fun and once I finish, whatever I do, it feels good."

And the year four student at St Anne's is even providing motivation for his proud parents.

"It does make you think, 'I'll get out and go for a run'," Rod said.

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"It's good to see a young kid, it was all him, nobody pushed him to do it, actually my wife 'Luc' (Luci) kept telling him to stop (laughs), saying 'come on, dinner's ready'."

It could take up to four months for Guinness World Records to verify the feat, but Zack has a more pressing matter - getting his beloved Brisbane Broncos a win.