Olive Glasgow-Collins, a physical therapist from Ware in Hertfordshire who specialises in posture and back alignment, says that school children who carry bags weighed down with books over one shoulder could be putting themselves at risk of back problems in later life.

Across both shoulders is the correct way of carrying a school bag

The correct way to carry bags is across the back, using both shoulders. But this method of strapping bags rucksack-style across children's backs suffers from not being "cool", she says. An alternative is for children to carry bags in their arms in front of them.

There can also be more immediate problems, as Mrs Glasgow-Collins says that she recently treated a 13 year old boy, referred to her by his GP, who had been suffering from strained ligaments in his back as a result of carrying a heavy school bag incorrectly.

To educate children into healthier ways of carrying bags and developing a healthier posture, Mrs Glasgow-Collins visits schools, giving lessons in "body mechanics" which shows the impact on the skeleton of different types of actions and suggests games and exercises that might prevent back ache developing.

"A few minutes in a PE lesson could save a great deal of difficulty in later life," she says.

Slouching can lead to back problems

As well as looking at the problem of back ache, Mrs Glasgow-Collins also looks at the ways in which children sit and stand. Sitting up straight can make a practical difference in preventing damage to the back, she believes.

Children who slouch over desks or put all their weight on one side are putting continuous pressures on their backs, the therapist says, and will be storing up problems for adulthood.

The therapist also believes that aerobics lessons and step exercises can lead to back problems in school children.