In Britain, back pain is the most common reason for absence from work, according to the National Back Pain Association. More than 100 million working days are lost each year to this widespread but intractable condition; the cost to the NHS is close to Pounds 480 million a year. To a school the cost can amount to a six-week supply bill.

Much back pain is work-related. Manual jobs that involve lifting are an obvious risk, so there are plenty of sufferers on building sites and in agriculture. The caring professions are not much better off; nurses, for example, suffer from lifting and turning their patients. But, like “builder’s back” and “hairdresser’s back”, “teacher’s back” is a condition well known to those whose job it is to put people back on their feet.

“They come in and say they’re a teacher and I more or less know what their problem is,” says Chris Turner, a chiropractor in Maidenhead. “If they’re in primary school, I know they’re going to have low-back pain, and perhaps mid-back pain, because they’re constantly stooping and bending. We get the lower back moving again, and give them things they can do if they have to work at low levels.”

Working with small children inevitably means getting down to their level for at least some of the time. But the “dwarf” tables and chairs commonly found in infant classrooms do not help matters. Pete Evans, spokesperson for the Association of Chartered Physiotherapists in Sports Medicine, sees a lot of teachers with back problems. “Primary teachers are expected to sit at the same desks as the kids, and doing that over a long period gives degenerative problems,” he says. “Things gradually erode over a period of time, and you end up with a disc prolapse, or muscle changes.”

When you are sitting, the spine should be bent slightly forward in an “S” shape, rather than slouched in a “C” shape. But the lower the furniture, the harder the “S” shape is to maintain. Crouching on a miniature chair may be good practice in terms of relating to your pupils, but over time it can damage the spine.

In Norway, most kindergarten children sit at adult-sized tables, on adjustable raised chairs with foot rests. Although designed to improve children’s posture, this arrangement has brought even more benefits for teachers, say fans of the “Tripp Trapp” chair widely used there. In the absence of this kind of furniture in British infant classrooms, the onus is on individual teachers to adapt their way of working to protect their backs.

Christine Ford, a 45-year-old part-time teacher at All Saints’ Primary School in the village of Trysull in Staffordshire, does not attribute her back problems to teaching. She put a disc out giving birth to her second child and has had intermittent back trouble since. She knows exactly what she should do - but admits that she doesn’t always stick to it. “Although you try not to bend, it’s quite difficult with six- to eight-year-olds,” she says. “I’m meant to kneel, but it’s much easier to bend over and speak to them. You’re not supposed to lift anything heavy either but occasionally you do have to. It’s a vicious circle.”

While constant stooping, bending and turning represents a threat to teachers’ backs, it is far from the only one encountered in school. Gillian Coffey, age 41, is head of Lynch Hill GM School, on the outskirts of Slough. She and her staff are at risk, she says, from “the child who wants to run out of the classroom, the temper tantrum, the fight”. Coffey, who already suffered from low-back pain, had a crisis after an out-of-control child was brought to her office intent on escaping from school. He tried to pull the door open, to run away, while she used all her strength to keep it shut until he calmed down. “A day or two later, my back went,” she says. “The doctor felt it was a typical teacher injury.”

Coffey is not the only member of staff at Lynch Hill who suffers from back pain. Of 20 teachers at the school, at least six have problems. “It’s quite a topic of conversation in the staffroom. Everybody knows what to do for a bad back - people are advised to go and hang from the wall bars,” she says.

While home remedies abound, few of the teachers interviewed by The TES had had time off work for their chronic back problems. Out of duty to colleagues andor commitment to the children, the most common solution to a back problem is to “work through it” - even if that means taking silent reading while lying flat out on the classroom floor. Most teachers who had taken time off had worked right up to the point where they could no longer stand.

Fear of being labelled a shirker is another inhibitor. “People often tend to think that having a bad back is just an excuse,” says primary head Barbara Clark. “That put a lot of pressure on me, at a time when I was in tremendous pain anyway.” Secondary teacher Kathryn Brewer agrees. “Because you haven’t got spots or your leg in plaster you’re not really ill.”

The National Back Pain Association slogan “Watch your back” has a particular resonance for some afflicted teachers. “At the end of the day,” says one secondary teacher, “you don’t want to be the one that’s off all the time because of the next round of redundancies.”

“I’ve never had time off work,” says 45-year-old primary teacher Denise Starr. “If mine starts to go funny, I lie on my back and do my knee-clutching exercises, or stick a bit of ice on it at lunchtime. I think you learn to live with it, and you compensate.”

fighting back: why it’s great when you’re straight

Be aware of your posture

Stand up straight

Sit up straight, with support for the lower back

Never bend when you can kneel or squat

Prepare yourself properly when lifting a heavy weight

Never stoop or bend for prolonged periods

Use one pillow and a good supportive mattress

Distribute heavy weights equally

Never take exercise without a warm-up or a cool down

‘The pain just arrived. I have no idea where it came from’

Kathryn Brewer, 34, teaches geography in an 11-16 comprehensive in the Midlands. She has been diagnosed as having a “chronic degenerative disc problem”, a condition that affects every aspect of her life. “I live with a pain at the bottom left-hand side of my spine, as if someone’s sticking a knife in it,” she says. “If I bend over I can’t stand up again very well, and occasionally my whole back goes into spasm.”

Brewer, a six-footer, has had back problems since childhood. She had reached 5ft 6in before leaving junior school, and long spines are more prone to problems. But her back has deteriorated in the past two years, and being a teacher doesn’t help. “You’re expected to carry piles of textbooks, lift overhead projectors, move desks,” says Brewer. “And if you’ve ever sat on one of those plastic chairs you’ll know they’re horrific. In an office, you could justify asking for a decent chair, but in teaching you know you shouldn’t be sat down - and the money isn’t there anyway. One of my colleagues is wheeling her own chair from home around the corridors of the school at the moment. ”

Stress and tiredness exacerbate the problem. “We’ve had the holidays, and I’m in a good phase. I’m swimming and I’ve got a new mattress and I’m using a lumbar roll at home. I’m trying my best not to aggravate the situation. By the end of term, I will have an awful lot of pain and the chances are that the whole of the bottom of my back will start to lock.

“I can tell you now that next year my back will be bad, because we’re being OFSTEDed.”

Brian Weston, 60, retired this summer as head of the 900-pupil Joseph Leckie school in Walsall. In his last year at school, Weston developed sciatica and was forced to have more time off - one month - than he had had in the previous 35 years of teaching.

“It just arrived,” he says, “and I have no idea where it came from. I suddenly found myself with pains in my leg, which kept getting worse and worse. Eventually, I was in constant pain, and I really couldn’t concentrate on what I was doing. I stood in a staff meeting one morning and started out upright and ended up bent double.”

Weston had physiotherapy, acupuncture and a fortnight off. “I felt slightly better but immediately I went back it started to get worse again,” he says.

“The only thing which appeared to work was to sit still, shut up and do nothing.”

The GP prescribed pills to help Weston do just that for a short period. An already-planned retirement followed shortly afterwards. Weston is not convinced that the stress of his former job contributed to his sciatica.

“The stresses certainly drive you barmy,” he says,“but they don’t do anything to your back.” None the less, since he retired last August, his health is greatly improved. “I get some twinges down my leg, but I don’t worry about those. Now I ride my bike, do a bit of exercising, play some golf. I did 30 miles on the bike this morning.” He sounds remarkably cheerful for someone who six months ago was unable to sit, stand or lie down in comfort.

Barbara Clark, 44, is head of Godolphin Middle School in Slough. Her back was injured in 1989, when a distraught junior pupil attempted to push her down the stairs.

“A girl began throwing furniture, and the teacher sent a child to get me. By the time I got there she was threatening to jump out of a second floor window. I tried to get her down to the ground floor, but at the top of the stairs she swung me round to push me downstairs. I fell into the bannister, and got a badly bruised back, and whiplash damage to the muscles.

“It was in October, a week before half-term. I was in agony over half-term but I continued to work, and because of that, the damage to the muscles got worse, not better. Eventually, I prolapsed a disc on to the sciatic nerve. I finally gave up during the February half-term. I was beginning to have difficulty walking, and could no longer pick up my two-year-old son.”

Clark spent the next five months lying on her back. A spell in hospital and specialist advice to rest and take painkillers did not help.“At one stage, ” she says, “I was beginning to wonder if I would ever walk again.”

A pack of frozen peas applied to the lower back eventually proved a turning point. “The cold made me numb enough to begin to move. Very slowly, I got mobile again. Now, I try to swim, which I find very helpful, and I make sure I have suitable chairs. But even now I get a sore back from time to time because the sciatic nerve was crushed, and will never be right properly.”