Straight back, bent knees advice is wrong, study finds

Henry Bodkin
Scientists say that conventional advice to always keep a straight back while lifting may in fact be wrong

“Keep your back straight, bend your knees.”

Whether at home, in the factory or in the office, it is the advice invariably issued to anyone preparing to lift a heavy object.

However, a group of scientists has called for a review of health and safety guidelines after claiming the technique is based on scant reliable evidence – and may even be inferior to a bent-back approach.

A new study argues that while most people instinctively believe lifting with a straight back is common sense, “round-back lifting” is more efficient and no more hazardous.

Published in the Scandinavian Journal of Pain, it points to research conducted on forestry workers which found that those who stooped to pick up their loads expended less energy than those who squatted.

The paper also argues there is “no significant difference” in spinal loads and compression forces between the two postures.

Despite the lack of evidence supporting a straight-back lifting technique, it is commonly believed to be the safest method and is taught to nearly every employee in the country upon joining a new company.

The NHS website states people should not bend their backs while lifting.

Meanwhile advice from the Health and Safety Executive recommends people squat so their thighs are parallel with the ground before lifting a load, limiting any bending to a small amount at the top of the back.

“Recent studies indicate there is a lack of in vivo (real life) evidence that support the notion of using a 'straight-back' in preference to a 'round-back' to reduce risk of LBP (low back pain),” the researchers at Curtin University in Australia wrote.

They added: “The findings of this study may have implications for ergonomic guidelines and public health information relating to bending and lifting back postures.”

It follows experiments conducted at Aberdeen University which suggested that a person’s lifting technique should be determined by the shape of their spine and not a one-size-fits-all approach.

The extent to which people’s spines curve at the bottom varies significantly, with those with curvier spines naturally stooping rather than squatting when they pick something up.

Professor Richard Aspden, who led the study, asked: “We’re clearly not all the same, so should guidelines be telling us to lift in the same way?”

Back pain, a significant proportion of which is caused by injury, is estimated to cost the UK one million years of lost productivity each year.

However, experts have claimed this figure is unnecessarily high due in part to GPs’ readiness to send patients for surgery or scans before trying simple physical and psychological treatments.

A review published in The Lancet earlier this year prompted the Chartered Society of Physiotherapy to call for “serious reflection” among doctors to prevent cases of minor back pain escalating into life-altering conditions.

Most cases of lower back pain respond to simple physical and psychological therapies aimed at keeping people active and able to stay in work.

People with significant pain are advised to keep moving, avoid languishing in bed and not to be put off lifting things.

Last year’s The Global Burden of Disease analysis found that low back pain is the leading cause of disability in almost all high-income countries as well as central and eastern Europe.