Repetitive strain injury (RSI) is a misnomer. It's not the repetition that causes the strain, but the muscle tension caused by the very small movements required to operate a PC.

So says Kevin Taylor, a doctor in electrical engineering who suffered from what has become known as RSI while studying for his PhD in New Zealand. Taylor cured himself, and has now formed a company, Niche Software, to help others avoid the pain.

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Repetition of large movements doesn't cause as much strain on the muscles as does holding the arms in an unnatural position for hours on end while making small hand movements, typical of the conventional desktop combination of keyboard and mouse.

Posture also adds to the strain. Most office desks are set up for optimum writing height — 100 to 110cm — too high for comfortable keyboard use, which should be 90cm. And most people sit too close to their monitors, causing eyestrain.

Taylor's solutions don't require sophisticated desktop products. In fact, he is quite disparaging about them, dismissing so-called ergonomic keyboards, wrist-rests, trackballs and mice as gimmicks.

"What's 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."

The one percent of the problem is wrist ache. In the US, RSI has become synonymous with carpal tunnel syndrome (CTS). Yet no scientifically valid studies have ever shown CTS to be caused by computer usage, says Taylor. Even the very worthy RSI Association is doing itself no favours with its misnomer of a moniker, says Taylor.

There's a utility available on the internet which doubles the sensitivity of your mouse, so you only have to move it a few millimetres to send the cursor across the other side of the screen.

"People think if you have to move less, you reduce the risk of RSI, but that's so wrong," says Taylor. "It takes more effort from your muscles to control the accuracy these small movements than to make large ones. You should decrease the sensitivity of your mouse so that you require most of your mousepad to get across the screen and move your mouse from the shoulder, not the wrist."

Brief moments of release

Taylor's main weapon in the fight against so-called RSI, is the micropause. Every five minutes, you let your arms relax down by your side for five seconds.

Fidgets have the right idea: type for a bit, then pace the office, type, yawn and stretch; type, throw a stressball at a colleague, type, gaze out of the window. And every time you stop typing to think, take your arms off the desk and let them drop.

If you're in an office and your boss tells you you're not working, quote to the boss Taylor's recovery corollary: "if you double the pain, you quadruple the time taken to recover."

The trouble is, you don't feel the pain until it's too late, says Taylor. After eight hours of manic non-stop keyboarding to meet an impending deadline, you feel stiff and sore. You probably need two days off to recover. If you'd religiously taken a five-second micropause every five minutes you would have worked another eight minutes. If you don't take time to recover, at some point the pain will become debilitating and you'll need eight months off.

Taylor's other two main defences are furniture correctly adjusted for height and screens that are far enough from the eyes and refreshed at a fast enough rate (in excess of 75Hz) to prevent eyestrain.

Time trials

Micropauses are the hardest thing to discipline into your working practice, says Taylor, and yet the most effective preventative treatment. Consequently, the Workpace package Niche Software produces builds these breaks into a complete workflow assessment for the individual worker by providing on-screen prompts. A trial version of Workpace can be downloaded at the site.

If you voluntarily take a break, the software won't prompt. If you naturally take breaks, the software will sit idle.

When office workers used manual typewriters, filing cabinets and leverarch files, they had natural rhythmic breaks to their workflow.

At a manual typewriter, you may have typed for an hour or more at a time, but at every line, you had to whack the carriage return, a large movement which broke up the many small ones. Auto-wrap and the electronic keyboard have put paid to that.

In the pre-computerised office, you also had to retrieve files from a filing cabinet drawer and operate other physical storage devices, such as leverarch files.

But everything is on your PC now. The typewriter, paper and filing cabinet can all be reached with a keystroke or mouse click — all constricted movements that require fine muscle control to achieve.

In the middle ages, there were all sorts of occupational diseases, injuries and hazards. They were fatalistically considered a consequence of one's vocation and inescapable. Millers with only one and a half arms were commonplace. In fact, housemaids knee is only just fading from the vocabulary.

These days we find such ignorance of health and safety in the workplace unacceptable. Lets hope the preventable injuries caused by use of PCs will become outmoded more quickly.