But should we be concerned about the weight children are lugging around?

Research shows that up to 30 per cent of teenagers in the UK are affected by back pain.

And for eight per cent of students - two to three in a class - the condition is severe enough to affect school attendance, concentration and their ability to play sport.

The research was carried out by the national charity BackCare and in response to the shocking findings it has launched a Protecting Young Backs campaign to try and raise awareness of the problem. It recommends that children should carry no more than ten to 15 per cent of their own body weight.

Warwick osteopath and professional member of BackCare, Rosie McCauley of Westbury Osteopathy wants to spread the word about preventative measures.

She said the blame for childhood back pain does not lay solely with heavy bags.

"It results from a combination of factors including children's general poor posture while sitting on furniture that's built for bigger people - whether working at a school computer or watching TV at home," she said.

"Carrying heavy bags is a major aggravating factor."

Ms McCauley added: "There is also a trend in schools for doing away with pupils' lockers, so a bigger burden of books is carried on a child's shoulders between lessons.

"The way the load is carried is crucial as well – in an effort to look cool some youngsters sling their heavy backpack over just one shoulder, or have it hanging low down their backs. This makes the strain worse."

Rosie McCauley is happy to give talks free of charge to groups of parents and pupils about how children can avoid back problems through good posture, appropriate furniture and exercise.

She is also offering ten per cent discount over the next month to any young person under the age of 19s needing osteopathic treatment. Call her at Westbury Osteopathy in Coten End, Warwick on 408885 or email: osteopathy@westburyhealth.com

q The www.backcare.org.uk website has ergonomically designed backpacks for sale at a starting price of £23.99 plus £4.99 p&p.