Whose secondary-school child doesn\'t leave the house without staggering under the weight of a schoolbag? Textbooks, homework, packed lunches, laboratory coats, sports kits and musical instruments tend to stay in their bags all day because the school lockers are usually too far away to be useful. A range of studies show that their bags weigh between 4 and 7.7kg, which, researchers estimate, is between 10 per cent and 17 per cent of the bodyweight of a 12- to 14-year-old. But does it matter? They are young and can bounce back, can\'t they? Apparently not, says research published recently in the Archives of Disease in Childhood. A study of 1,403 Spanish children aged 12 to 17 found that 61 per cent had backpacks exceeding 10 per cent of their bodyweight and that these children were more likely to get back pain than children carrying lighter bags. There is also some evidence that people who have back pain when they are young are at increased risk of having it in adult life — a study of 10,000 Danish twins said the risk was up to four times higher. This latest research, however, does not prove that heavy bags cause back pain in adolescents — it only shows that there is an association. Back pain is also caused by sedentary lifestyles; being slumped in front of the TV leads to weaker back muscles. While carrying a heavy bag affects how you walk (for example, changing the head-neck angle, making the shoulders asymmetrical and increasing how much the hips and knees move), there is no evidence that it causes any lasting deformity, such as scoliosis, which is a curvature of the spine. But it seems common sense to check your child is carrying only what they need for that day, and in a bag that is comfortable. Backpacks should be best, because they have two shoulder straps — a bag carried on one shoulder is more likely to cause pain. But often backpacks end up weighing against the lower back. The bag should be sturdy and have wide, padded, adjustable straps. If you can get a backpack with hip straps, this will provide additional support for your child\'s back. From gulfnews