Of mice and men – International RSI Awareness Day

Why do you get RSI?

It could happen if you for some time have exerted certain muscles through low-strain tasks. Like using a computer and a computer mouse in your everyday work. You might experience a pain in the arm, neck, wrist and fingers. That pain is caused by an increased strain in the muscles and ligaments, tendons or nerves being overloaded. Also, stress can increase the risk of RSI because you often tighten your muscles.
When working with a computer mouse, you hold your hand in an unnatural position, both holding the mouse and clicking it. The hand is bent back in an unnaturally large angle between the forearm and the hand and the muscles are constantly strained. In addition, the hand is usually slightly twisted, with a turn to the little finger. This causes a greater pressure on certain nerves and the muscles in the forearm are forced to work in an unnatural way.

What did you find in your study of so-called ergonomic computer mice?

First, I would like to point out that a so-called ergonomic computer mouse cannot have good ergonomics in itself. It is only in collaboration with the user we can study how well it can avoid incorrect use which may cause RSI.

In our evaluation, we took a closer look at four ergonomic computer mice of different brands. We examined two aspects – usability problems and use errors – in interaction with the mice.

In the study of the four mice, we found 75 possible ways to use the mice incorrectly! The user did not understand from the design of the mouse how it was supposed to be held or which finger to use to click. From this, we found that it was difficult for the user to guess how an ergonomic mouse should be used properly. And the wrong use causes a strain in the wrist, hand and fingers which in the long run can lead to RSI.
The study shows the importance of informing and educating the users on how to handle an ergonomic mouse properly. We also found that it is important to develop mice that you intuitively understand how to use. The best design is the one where you can only use the product in one way – the correct way.

What are your best tips to avoid RSI?

There is no special treatment for RSI. Instead you need to find a way to prevent long-term strain. These simple tips can prevent RSI and reduce existing problems:

• Take more breaks! Rather many short breaks than a few long ones.
• Change work posture frequently.
• Stretch your body and your wrists.
• Avoid using the computer mouse – learn how to use keyboard shortcuts instead.
• Change hands maneuvering the mouse. It is difficult at first, but practice and you will get in to it.
• Make sure the mouse and keyboard are at a proper distance from the body, the closer the better.
• Keep the wrist straight, slightly twisted towards the little finger when using the mouse, ie try to hold the wrist in a natural posture to reduce strain.
• Reduce work-related stress.

About

Anna-Lisa Osvalder researches in ergonomics and biomechanics since 1986. She is a Professor at the Division of Design & Human Factors, Chalmers University of Technology as well as Professor of Human Machine Systems at Design Sciences, Lund University

The study mentioned above is part of the doctoral thesis "Predicting mismatches in user-artefact interaction" by Lars-Ola Bligård (search for “Appendix A PEEA: Evaluation of ergonomic error in the interaction with computer mice”).