Beware of... Mouse?

When someone mentions "safe mousing," it's almost amusing. "How in the world can someone injure himself using a mouse?!" Believe it or not, the thousands of clicks you perform in a normal day can cause significant damage to your arm, wrist and shoulder. Repetitive Strain Injuries (RSI) such as Carpal Tunnel Syndrome are a very real threat to most information workers. As part of our ongoing effort to help you achieve maximum effectiveness at work, here are 10 tips to avoid the stiffness and soreness that foreshadow an RSI. 10 Tips for Safer Mousing 1. Mouse Grip - don't squeeze or grip the mouse between your thumb & pinky. Your hand should be relaxed, not tensed when using the mouse. 2. Mouse Size - hands come in different sizes just like feet. Choosing a mouse that fits your hand will help you work with an open, relaxed hand posture. 3. Mouse with the Arm - don't twist your wrist side-to-side while mousing. Move the mouse with the whole arm, using the elbow as a pivot point and keeping your wrist in a straight, neutral position. 4. Mouse Position - Awkward Positions: Body postures determine which joints and muscles are used in an activity, as well as the amount of force exerted. Poor postures place unusual or excessive forces on components of the body. The number one problem with pointing devices has always been location. In the best of circumstances, pointing devices are placed just to the right of the keyboard, and at worst, they are placed on a side surface or on the surface in front of the user because there isn't room on the keyboard tray. Effect of Mouse Position on Shoulder Muscle Activity: The location of the pointing device during use, (in relation to the body's midline) affects EMG muscle activity for the anterior and middle deltoid muscles. (Cook and Kothiyal, 1998). EMG activity increases as the mousing area is moved farther from the body's midline, as shown by the research performed by Alan Hedge and Greg Shaw at Cornell University. They measured EMG activity in relation to the shoulder abduction angle required by the placement of the pointing device. Note how much muscle activity is present at 50 degrees shoulder abduction. This mousing position, (just to the right of the keyboard) would be considered a best case scenario for most users. Effect of Differing Shoulder Widths: Computer users come in all sizes. A man that is 6 foot 5 inches tall, with a large bone structure could measure 28" through the shoulders, while a 5 foot tall, petite woman might be only 15" through the shoulders. In the Cornell research, when the mouse was positioned just to the right of the keyboard, the test subject's shoulder abduction was at 50 degrees. The 6" 5" man with a 28" shoulder width might have only been at 40 degrees abduction for the same position. The strain on his shoulder is reduced because of his size. On the other hand, the 5" petite woman with a 15" shoulder width might have a 60 degree abduction with the same mouse position. Her size will cause her to be at even greater risk of injury. 5. Avoid Restricting Circulation - there are exposed blood vessels near the skin at the wrist, where the pulse is taken. You don't want any pressure to this region, as it will reduce circulation into the hand, increasing the risk of injury. 6. Don't use a Wrist Rest - research has shown that using a wrist rest doubles the pressure inside the carpal tunnel, and it acts as a partial tourniquet reducing critical circulation. Also, you can't "Mouse with the Arm" and use a wrist rest at the same time. 7. Mouse Settings - adjust the speed and acceleration for your mouse. By making this adjustment, you will be able to reduce the amount of arm/hand movement needed to get from one side to the monitor screen to the other. To adjust these settings, do the following: Open the Control Panel. Double Click on the "Mouse" icon. Click on the "Motion" tab. In the box that says "Speed," change the speed from the default 25%, to 75%. In the box that says "Acceleration" change from "None" to "Low" or "Medium" Click "Apply" to test out the new settings. Adjust them more if necessary. Click "OK". 8. Mousing Height - adjust the height of the mouse so your wrist is straight while mousing. The top of your hand should not be bent back toward your body while mousing. 9. Mouse Designs - consider using a mouse that is designed to support the weight of the arm and hand while mousing. This reduces the strain to the neck and shoulders, and is actually essential if you don't have Proper Forearm Supports to use. o The Quill Mouse (Offered in right and left-handed models) Best pointing device we've seen to date. o The Contour Mouse (4 right-hand sizes, 3 left-hand sizes) o The Renaissance Mouse (2 right-hand sizes) o The Whale Mouse (adjustable size, non-handed) o The Easy Cat GlidePoint Mouse (non-handed) 10. Load Sharing - consider alternating between the left and right hand to reduce the workload and strain on the one hand. This can be done using a non-handed mouse like the Whale Mouse, or the Roller Mouse, or by using a Dual Mouse Adapter and a Left-handed mouse. Another option for mousing with both hands is to use a keyboard with a centralized pointing device like: o The Northgate Evolution Keyboard with Glidepoint Mouse. o The Pro Curve Keyboard with Glidepoint Mouse.