Sending employees on courses to encourage "safe lifting" does not reduce back injury rates, say experts.
Acute low back pain is very common
A Finnish study said either workers were still ignoring the advice - or bending your knees and keeping your back straight simply does not work.
Writing in the British Medical Journal, they said that a "no lifting" policy might be more effective.
The Health and Safety Executive said that courses were no "panacea" for injury risk.
It is estimated that up to four out of five people in the UK will suffer back pain at some point in their lives, and that injuries sustained at work cost companies millions each year in lost productivity.
The research, from the Finnish Institute of Occupational Health in Helsinki, looked at 11 different studies into workplace back injuries.
They compared employees who had been sent on "safe lifting" courses, which showed them the "correct" way to carry heavy equipment and boxes, and those who had not received any training.
There was no difference in the rate of injury between the two groups.
The researchers wrote: "Either the advocated techniques did not reduce the risk of back injury or training did not lead to adequate change in lifting and handling techniques.
"Many health professionals are involved in training and advising workers on lifting and handling.
"Even though there may be other reasons to continue this practice, this review does not provide evidence that it prevents back pain."
Professor Niels Wedderkopp, from the Back Research Centre at Funen Hospital in Denmark, said that the results were "disappointing, but not surprising", given that the origins of back pain were still not fully understood.
A spokesman for the Health and Safety Executive, which encourages safe lifting techniques as part of its "Better Backs" campaign, said courses should not be viewed as the complete solution.
He said: "They may help but they are not necessarily a panacea.
"We encourage people to take a risk assessment, to ask whether there is any need to lift the heavy object, or whether there is a safer way to move it?"