Most 'ergonomic' computer products which claim to reduce the risks of RSI do nothing of the sort, according to Dr Kevin Taylor, an expert in computer-related illnesses.

"What is ergonomic about the Microsoft Ergonomic Mouse? It's just another mouse," said Taylor. "If it does have an effect, it addresses less than one percent of the problem." Taylor gained his PhD in electronic engineering.

The mistake most so-called ergonomic products make is to concentrate on the wrist, says Taylor, whereas 99 percent of problems should be addressed through regular 'micro-pauses', better posture and avoiding eyestrain.

The only products which have much effect are height-adjustable furniture which can be used to regulate posture, says Taylor. Yet mice and keyboards labelled 'ergonomic' typically sell for several times the price of their conventional equivalents. For instance, standard mice can be bought for less than £5, whereas 'ergonomic' versions such as Microsoft’s IntelliMouse cost around £25. Similarly, basic Qwerty keyboards can be had for around £10 while Microsoft’s Natural Keyboard Pro will set you back at least £31.

Even the term RSI (repetitive strain injury) is a misnomer, Taylor told a recent conference of the RSI Association. "Repetition isn't the problem, rather it's the tension caused by lack of breaks and [the need for] fine muscle control."

Repetition of large movements rarely causes RSI, but working at a computer constrains movement to a very small field and this causes tension and bad posture, says Taylor. This can only be relieved by taking regular breaks and by relaxing the muscles concerned.

Taylor suffered from computer-related injuries while studying in New Zealand and has researched the subject extensively. His company, Niche Software, produces a program called Workpace, intended to analyse people's working practices and implement a scheme to reduce the risks of computer-related stresses.