Product Review
February 2002

Mouse-Attached Palm Support

I recently came across a product that attaches directly to the mouse to provide palm support in an effort to flatten the wrist. As my clients can attest, I have long been a proponent of palm support when using the mouse. Before I tell you about my experience with this product, I should explain why I believe that palm support is needed.

Mousing is a fine motor task. A fine motor task is one that requires constant visual monitoring. While I can close my eyes for a minute while typing and still have a reasonable outcome (indicating that touch typing is a medium motor task), I cannot close my eyes while using the mouse and have any semblance of positive outcome.

Writing is another example of a fine motor task. In addition to needing to watch the process to do continuous corrections to the control of the task, the arm needs support to maintain control. Try writing your name on a piece of paper without any point of contact from your hand or arm. Do you notice the tension in the arm and shoulder to maintain control? Notice how relaxed the arm and shoulder muscles are when your hand is allowed support from the desk surface.

Fine motor tasks need support. If the arm is not supported during a fine motor task, the arm and shoulder muscles will be continuously active to stabilize the hand and arm. These muscles are intended for gross motor movements – pushing, pulling, throwing, etc. – activities that move the upper arm. Using them for fine motor tasks requires them to be continuously active to stabilize the hand and lower arm. A muscle holding a contraction (or only making minute movements) restricts its own blood supply, increasing the risk of damage through the build-up of lactic acid and other by-products of metabolism.

The hand, wrist or arm will automatically seek a level of support when doing a fine motor task. In the case of the mouse, the wrist will drop to the desk surface. This results in the knuckles being higher than the wrist and means that the tendons responsible for finger movements must work around the angle in the wrist. This increases the load on the tendons and on the muscles to which the tendons are attached. Additionally, it is usually the carpal tunnel area of the wrist that falls onto the desk surface, increasing pressure within the tunnel.

The device that attached to the mouse did provide support for the hand in order to flatten the wrist. Unfortunately, because the support surface was mobile – it moved with the mouse – the shoulder and arm muscle were still called into play to stabilize the arm. Within a couple of hours of computer work, I could feel burning in the anterior rotator cuff and biceps tendon. Luckily, I had the sense (and opportunity) to take a break.

I did want to the give the product a fair try, so I used it for a full month. I now have a mild irritation to the anterior shoulder and find my neck a bit stiff on that side. I am looking forward to resuming use of my mouse pad with a gel palm support so that my shoulder can relax. Notice that I use the term "palm support"! The fleshy area at the base of the hand that should be supported. The wrist should not have pressure on it. The carpal tunnel area is too unprotected to sustain pressure for any period of time.

Of course, any activity done to extreme will cause irritation… excessive mousing, even with palm support to keep the wrist flat can irritate the muscles and tendons of the forearm and hand. And if the hand and mouse slip forward, there can be pressure on the wrist and carpal tunnel.

The key is, as always, limiting exposure. Take a break or add variety to the tasks. Do stretches for the hand and arm. Limit the time doing any one dedicated task to 45 minutes. Remember, a change can be as good as a break, provided that you are using different muscles.

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