A review of published studies has found no evidence carrying schoolbags is causing back pain in children and adolescents.

Carrying a schoolbag does not cause back pain in children and adolescents, a systematic review of all the evidence has concluded.

Researchers at the University of Sydney looked at 69 published studies on backpacks and back pain involving more than 72,000 students with an average age of 12 to 14 years.

Contrary to popular opinion, the analysis found no convincing evidence to suggest there was a link between back pain and the use of backpacks.

Not even weight, the type of bag or the way kids carried backpacks influenced the risk of back pain, said senior author Associate Professor Steven Kamper, an expert on paediatric pain from the University's School of Public Health.

"We found a few studies which showed a relationship but lots and lots of studies which showed there was no relationship at all," said Professor Kamper.

"If there was a cause and effect relationship it would have been apparent. It looks like people have just jumped on backpacks as an easy target without the evidence, and it's stuck," he said.

There are various guidelines that advise only carrying 10 per cent of body weight and statements from professional groups that endorse particular brands of backpacks.

The findings, published in the British Journal of Sports Medicine, call into question those recommendations, Professor Kamper says.

"I'm suggesting they are not really based on any scientific evidence," he said.

Like the adult population, back pain is quite common among children. Studies have found around 18 to 24 per cent will report back pain at least monthly.

Unfortunately, the cause of childhood and adolescent back pain remains a mystery and not even bad posture is thought to be the culprit, said Professor Kamper.

For most, the pain will easily subside without the need for intervention.

"But there is a substantial minority for which that pain continues and becomes persistent and has an impact on schooling and mental health as well," said Professor Kamper.

He's called for further research to help understand how to distinguish between these two groups and what is causing the pain.

This could also help prevent chronic back pain later in life, said Professor Kamper.

"The evidence we see now is that the kids that experience persistent, chronic back pain are more likely to become adults that have those same problems as well," said Professor Kamper.