Heavy burdens

The start of a new school year should be a time of excitement for children, but for many the reality is misery and pain as they carry the weight of the world on their shoulders. Experts warn that heavy, overloaded school bags are contributing to an alarming epidemic in back pain among children as young as four. A recent study by Shelley Goodgold, an associate professor of physical therapy at Simmons College in Boston and a member of the American Physical Therapy Association, revealed that 55 per cent of children carry backpacks that are far too heavy for their frame.

According to Goodgold, hauling around bags that weigh more than 15 per cent of a child's body weight can cause serious damage to developing musculoskeletal systems. "As the muscles and soft tissues of the back are forced to do more work than they should be doing, they become strained and fatigued," she says. As a result, a growing number of children are suffering muscle strain, pinched nerves, numbness and even temporary paralysis due to the kind of back pain that once afflicted only adults.

Goodgold found that one third of children reported back pain severe enough to cause them to consult a doctor or miss school. Surveys by the UK back pain charity Back Care show the figure to be as high as 50 per cent. For many, the pain is chronic and recurrent. A study at the University of Southern California found that more than 80 per cent of children with aching backs believe their heavy school bags are to blame. But overloading a bag is easily done.

By the time they have packed their textbooks, physical education kit, calculator, pens, mobile phone, lunch and bottled water, about 54 per cent of pupils carry bags weighing close to 40 pounds - the equivalent of a grown man strapping a microwave oven full of food to his back all day, according to surveys by the British Chiropractic Association (BCA). "If your child has red marks on their shoulders, neck pain or numbness and tingling in their arms, their bag is way too heavy," says Tim Hutchful, a spokesman for the BCA. "Other signs are if their shoulders are rounded because they are not standing properly, if their stomach sticks out or if their walking action seems strange."

Goodgold says that there is a simple way to check the effects of heavy backpacks: "I always challenge any doubting parents to try wearing their child's backpack loaded to 15 per cent of their own weight," she says. "They soon realise that urgent action needs to be taken to prevent children struggling with unreasonable loads." Some bags are better than others. Janice Clark, a paediatric physiotherapist and spokeswoman for the Chartered Society of Physiotherapy, says the best option is a backpack (with two straps) from a sports shop rather than a fashion store. "Look for wide, padded straps and a waist belt, which will help to redistribute the weight from the shoulders and back to the pelvis," she says. "A padded back will also help to reduce pressure on the back, shoulder and underarm regions."

Multiple pockets and compartments also help to spread weight evenly. Even if your child has a bag with two shoulder straps, there is a temptation for them to sling it over one shoulder. However, this bad habit can cause leaning to one side as a child tries to compensate for the extra weight, resulting in an asymmetrical spine, back pain and strained muscles in the shoulder and neck. In severe cases, children can develop a condition called "scapular winging", in which the nerve that supplies the shoulder muscle becomes pinched, causing paralysis.

"Backpacks should always be worn over both shoulders to avoid over-stressing one side of the body," says Clark. "If that happens, it can damage postural shape and speed up degeneration of a growing spine." For the same reasons, bags with one shoulder strap that runs diagonally across the body should be avoided as they don't distribute weight properly. Contrary to the common belief that the weight of a bag should be carried high on the back, guidelines by the American Academy of Paediatrics suggest the safest place for the weight to be positioned is mid-back; it should sit evenly, not sag towards the buttocks.

It is recommended that children take care when putting on their backpack - they should keep their trunk and back stable to avoid twisting. Goodgold says that while backpacks with wheels can be a good idea, they present their own problems when it comes to manoeuvring them around school corridors and in and out of lockers. "Wheeled backpacks tend to be heavier than standard bags so that needs to be taken into account," she says. "If you do choose one, make sure it has wheels that are big enough to ensure it doesn't wobble over and a handle long enough for a child to wheel the bag without repetitive twisting and turning."

Keeping active is also a vital part of keeping young backs healthy. Movement of any sort, even walking around a classroom, squeezes and stretches the discs, the small cushions between each vertebra that act as shock absorbers for the spine. This motion pumps nutrients and oxygen around the body to keep the discs healthy. Inactivity, on the other hand, starves them of nutrition and may trigger pain.

"The simplest movements can be beneficial," says Dr Dries Hettinga, a medical adviser to Back Care. "Turning round from side to side, or even the movement involved playing board games or doing jigsaw puzzles can improve the health of the spine." And what do you do if acute pain strikes children under 12? Clark recommends consulting a doctor immediately. With teenagers, a hot water bottle or ice pack applied to the area can provide immediate relief.

"If the pain lasts for more than a week, see their GP, who might advise they see a paediatric physiotherapist," Clark says. "They will suggest suitable exercises to reduce pain and reoccurrence." Proportion A child's backpack should weigh no more than 15 per cent of his or her body weight. Weight If a school bag weighs 12 pounds and a child lifts it 10 times a day, the child is hauling around 120 pounds a day on an average of 180 school days a year. That's more than 21,600 pounds lifted every 12 months.

Lockers Make sure your children have school lockers and that they deposit some of the contents of their bags into them each morning. Chair If your child uses the computer at home, invest in an adjustable chair that supports the upper and lower back. Desk An old-fashioned sloping desk is kinder to the back than the tabletop variety. Activity Keep an eye on children's weight and exercise habits. A study conducted a few years ago at the University of Michigan's Spine Program centre showed that being overweight and inactive were primary causes of the rising trend in back pain among young people.

Movement Immobility is a key factor in back pain. Children should sit at the computer or in front of the television for no more than 30-40 minutes without getting up to stretch or walk around. If children move too little, their chest muscles shorten and back muscles lengthen. The deep stabilising muscles of the spine that should be relaxed and released become tight and tense so that pain is almost inevitable.