Design for a Computer Mouse

Julie Eriksen

The computer mouse was selected for redesign to minimize cumulative stress disorders associated with current mouse designs (Smith 1997). These disorders arise from excessive hand extension, wrist deviation, arm abduction, and pronation required to use mouses currently available (Smith 1997). Less fortunately, mouse use with the hand placed palm down leaves users able to easily engage in ulnar/dorsiflexion deviations to control mouse position without moving their arms, leaving them prone to injury (Smith 1997). People who work in data entry who must use mouses for eight hours/day are at most risk because of frequency of use.
Computer mouses are data entry instruments used both to control curser position and for function selection. Curser movement corresponds to mouse movement, while functions are selected using the fingertips to press buttons located on top of the mouse. To move the curser, the user drags the mouse around in corresponding movements to the curser's movements, typically on a horizontal surface located next to the computer being used. Usually the mouse is controlled on top of a foam pad called a mousepad. Use of the mouse when placed to the side of the computer can lead to excess stress on the shoulder and back muscles because shoulder abduction is required (Harvey 1997). However, as mouse placement relates to space constraints, resolving this issue is quite difficult (Sanders 1993).

However, it is recommended that if at all possible mousepad design should permit mouse use on the user's lap, or directly in front of them, to minimize shoulder abduction. Mice are problematic because due to the mouse's size, a power grip is required, rendering instrument control through precision gripping, the grip used for stylus writing, impossible(Sanders 1993; Casteillo 1992).
Wrist/forearm positions used for writing with writing instruments such as pens, are inherently lower stress than those positions used with current mouses (Hedge 1997). Writing positions typically require the dorsal side of the wrist to face away from the saggital plane of the body. So for mousing activities, during which the elbow is typically flexed so that the mousing surface may be accessed comfortably, the palm must permitted to face toward the saggital plane of the body.

Consequently, the redesigned mouse's casing should permit the user mouse use with the arm arranged in positions similar to those used for writing. More significantly, this sort of wrist position prevents unhealthy ulnar/radial deviations because up-down movements resulting from deviations while the wrist is aligned in positions appropriate to writing, are not useful for mouse control, as that requires the mouse be moved from side to side. In addition, the wrist is much more flexible in extension and flexion behaviors than in ulnar and radial deviations. (Ryu 1991) Therefore, extension and flexion of the wrists may prove less harmful to the wrist for mousing activities, than deviations normally used with current designs, because of the wrist's inherently greater ability to manage flexion and extension behaviors.

Current mouses designs prove problematic because typical control placement at the distal area of the mouse requires finger control. Excessive use of the fingers can result in trigger finger. (Hedge 1997) The thumb is better adapted to repetitive use, because the thumb makes use of strong muscles originating in the palm, so function control should permit thumb control of most used functions (Sanders 1993). In addition, the palm down position required of mouse users to operate current mouses can result in users resting their palms on the mouse casing, putting users at risk for compressing nerves and tendons located close to the surface (Sanders 1993).

Because fingers one and two oppose each other, permitting precision gripping of objects, a curved gripping surface is well suited to follow the resultant arch formed in the hand through finger opposition created by hand geometry. More of the user's palm can contact the mouse's surface, permitting force transmitted through the user's hand to be distributed over a larger surface area, minimizing compression stress (Sanders 1993).

Palm down grips typical of current mouse casings often result in a pinch grip, by which opposition of the thumb and distal joints of the fingers act to grip the mouse (Hedge 1997). Placing the palm on a mouse while the elbow is flexed with dorsal side facing the floor requires the wrist engage in radical static radial deviations, because: 1) the elbow can only flex and extend along one plane; 2) the palmar side of the hand faces a similar direction as the frontal side of the elbow in the anatomical position; therefore when the frontal side of the forearm faces the transverse plane so must the palmar side of the hand. Turning palm down corresponds to a radial deviation. Prolonged use of mouses with the wrist placed in this position can cause epicondylitis and other repetitive stress disorders, and in addition, reduces grip strength (Sanders 1993).

This radial deviation affected pinch grip is particularly weak, because the twisted position of the wrist circumvents use of arm muscles to control the mouse (Sanders 1993). Consequently, only a limited amount of surface area -- that of the thumb and finger tips, can be used to transmit force from the fingers to the mouse, so undue stress on the fingers and thumb can result.(Sanders 1993) However, mouses may have a distinct advantage over stylus because of their size. The mouses's size should permit, if designed properly, for the user to use many surfaces of their hand to control the mouses, rather than just the finger and thumb tips, unlike styluses. Therefore, the redesigned mouse should not only permit users to contact the mouse with more touching surfaces, but should permit the user to grip the mouse with their wrist in a less radially deviated position. Therefore, with criteria set up to permit optimal interface of the user's hand with the mouse, plans for a redesigned mouse will be outlined below. Sketches of the redesigned mouse and associated diagrams are located in the Appendix (# refers to diagram number to refer to in the Appendix ).

Gripping surfaces located on the side of the mouses will be curved to permit the fingers to cup the side of the mouse. (#2) This hand orientation on redesigned mouse should result in the distal palm will be making good contact with the curved gripping surface, object contact typical of power grips. (Sanders 1993) The shelf formed varies from one to two inches, to permit both adjustability to varying hand size and maximized power grip of the mouse (#3) (Hedge 1997). In addition, the mouse will be covered with a somewhat rough material, to increase friction between the user's hand and the mouse, to reduce strength needed to manipulate the mouse(#2) (Kawai 1995).

The redesigned mouse will feature controls located on the top of the mouse and on the front sides(#1,#2). The top button permits thumb control of functions, and is located where the thumb will rest naturally on the mouse. The forward buttons permit finger control, and are located in the approximate position the fingers will rest naturally when using the mouse. The narrow tear drop shape ranges from 2.5 -3.5 inches across the axis formed between the thumb and finger controls, to permit adjustability to hand size and to maximize grip strength (Sanders 1997). Finger buttons located on each side of the mouse's tip permits both left and right handed people to use the mouse. The thumb control's position is centrally located so that handiness doesn't affect thumb control of the mouse -- both types can rest their thumb in approximately the same place on the mouse. Controls will be rounded and covered with very firm foam, similarly to the optimized contours of seat cushions, to permit good adjustability to a variety of finger and thumb shapes and sizes operating the mouse controls (Hedge 1997).

Because curvature of the shelf/gripping surface of the mouse follows that of the arch formed by the hand, the user is permitted to contact the mouse's surface with a good percentage of the palmar side of their fingers and main hand.(#5) Consequently, the force required to move the mouse is minimized, reducing muscle fatigue(Sanders 1993). Because the curvature of the mouse is smooth and flatter than the contours of the palm, it should not contact the hollow of the palm, so risk of compressing this sensitive area of the hand is minimized (Sanders 1993).

The more narrow precision grip and less radially deviated wrist position afforded by the new mouse design consequently permits better control of the mouse by permitting use of palm muscles such as those controlling the thumb (#4)(Sanders 1993). Use of these strong muscles rather than the fingers, as with a stylus, can risk of finger fatigue, by reducing force transmission through the fingers. Specifically, the more straightened wrist position afforded permits the user to more readily transmit force from their arm muscles down through their palm (Sanders 1993). Therefore, the user can rely on the more powerful, larger muscles of their arms to supply the primary force required to push the mouse around for curser control, further reducing risk of hand fatigue. (Hedge 1997) Secondary fine control of mouse position can be supplied by fine movements of the wrist and palm, similar to writing, without finger fatigue associated with internal precision grips used for stylus writing (Hedge 1997).

Finally, the broad base of the teardrop shaped mouse provides a good broad surface for the palm of the hand to contact the mouse. (#1) Thereby, force from contacting the mouse can be spread out all over the hand, minimizing compression stress (Sanders 1993).
In conclusion, the redesigned mouse, for reasons cited above, should permit better mechanical interfacing between the user's body and the curser control, than current mouse designs.



REFERENCES
Sanders, M. et al. Human Factors in Engineering and Design. 371,383-412. 1993
Hedge, Alan 325/651 class notes. 1997
Kawai, S. et al. "Effects of varied Surface Conditions on Regulation of Grip Force During Holding Tasks Using a Precision Grip" Japanese Journal of Physical Fitness and Sports Medicine 44(5). 519-538. 1995
Smith, W. et al. "Ergonomic Test of Two Hand-Contoured Mice" Global Ergonomic Technologies, Inc. press release. 1997
Ryu, J. et al. "Wrist Joint Motion" Biomechanics of the Wrist Joint. 27-60. 1991.
Harvey, R. et al. "Surface Electromyography and Mouse Use Position. Ergonomics (40) Aug. 781-9. 1997
Castiello, U. et al. "Does the Type of Prehension Influence the Kinematics of Reaching?" Behav Brain Research. (50) 1-2. 7-15. 1992



http://ergo.human.cornell.edu/CUHFdownmouse.html





APPENDIX
http://ergo.human.cornell.edu/ErgoPROJECTS/97projects/mouse.gif

WristThotic Wrist Support

Dateline 03/21/2000

When I wrote my article "Big Mouse, Less Pain?" back in January, I could hardly have predicted the reader response. Repetitive strain injury resulting from mouse use has been a major problem in the lives of computer users, and many folks contacted me with suggestions and questions about mouse-induced pain.

One of those people was Don Corbett, developer of an unusual product called the WristThotic. The WristThotic is a wrist support pad that attaches to the back of the mouse, providing many of the benefits of both a larger mouse and a wrist pad. Photos below show the WristThotic attached to the back of a Kensington USB mouse.

To accomplish its purpose, the WristThotic uses a soft velvet surface on top and a slick vinyl underbelly which slides on any smooth surface.

Having used the WristThotic for a couple of weeks, I can say that it works as advertised. It provides good support for the wrist and it's just flexible enough to allow for precise mouse positioning without excessive stress on the shoulder and arm. It's certainly superior to a fixed wrist pad, and appears to accomplish the goal of reducing wrist deflection much the same as an extra-large mouse. If you suffer from hand pain, tingling or numbness when using the mouse, WristThotic could help.

To use the WristThotic, you'll need a large, smooth mousing surface. You'll either need a large mouse pad or a bare tabletop, or a very thin mouse pad like the 3M Precise Mousing Surface. You need plenty of room for the pad to float around behind the mouse. You may also want to elevate the mouse above the keyboard, as it's generally believed that the appropriate height for the mouse is slightly above the natural location of the elbow joints.

Will WristThotic take the punishment of daily use? I can't really say, as I've only had the opportunity to test it for a couple of weeks. But even if you only get a few months of use out of a WristThotic pad, it's still a good deal at $6.00 per unit, or $12.00 for a three-pack. It's probably the cheapest computer add-on you'll ever buy!

For more information, consult the following resources:

• WristThotic
  Don Corbett's web site, with secure on-line ordering of the WristThotic product.
• Big Mouse, Less Pain?
  My original article on preventing carpal tunnel syndrome with a large mouse, with a dozen links to important RSI resources.
• Input Device, Mice
  Links to mouse vendors and information sites.
• Repetitive Strain Injury
  My own list of links to RSI sites and resources.

Previous Features

All text and photos by Rick Russell.

 
Cornell University Ergonomics Web

Dateline Jan. 15, 2000

The Pain of Using a Mouse

All frequent computer users have felt the twinges that result from an entire day of mousing and typing. For some unfortunate folks, these aches and pains develop into a full-fledged syndrome which can render their fingers and hands weak and inflexible, preventing them from using computers or even turning doorknobs and opening pickle jars.

... the Whale is about an inch longer than a Microsoft-brand mouse, and ... it adjusts for even larger hands.

His big test mouse was The Whale by New York firm Humanscale Technologies. Unfortunately, Humanscale's web site is somewhat limited, and offers no data on the mouse itself. According to the NYT article, the Whale is about an inch longer than a Microsoft-brand mouse, and it has an extensible plate so that it adjusts for even larger hands.

The most common hand-related RSI is Carpal Tunnel Syndrome, an inflammation of the lining of the tube that shields the nerves to the hands.Grouped under the general classification of Repetitive Strain Injury ("RSI"), these injuries are hardly new. The meat-processing industry was the first to see frequent complaints of hand pain, numbness and stiffness, and those problems are still reported today in that industry. The most common hand-related RSI is Carpal Tunnel Syndrome, an inflammation of the lining of the tube that shields the nerves to the hands. As this lining becomes inflamed and swollen, pressure on the nerves can cause unpredictable results, including pain, numbness, tingling and stiffness.

Use of a computer mouse is a frequent cause of RSI. Because the mouse requires all kinds of bending & twisting of the wrist and fingers, it's easy for heavy use to cause painful carpal tunnel inflammation.

An Easy Solution?

The New York Times reported in its Jan. 13, 2000 issue suggests that the solution may be a big mouse. Professor Alan Hedge of Cornell University's Department of Design & Environmental Analysis has been studying the way human hands grip, hold and use the mouse. By hooking up test subjects to electrodes to measure deflection angles and muscle strain, Dr. Hedge concludes that larger mice induce less stress and less severe angles in the wrists.

Dr. Hedge concludes that a larger mouse reduces the average deflection angle of the wrist and the frequency that the deflection angle enters a dangerous range. Although deflection angle does not by itself cause carpal tunnel syndrome, frequent intense deflection is likely an important factor. Dr. Hedge noted that the larger mouse took pressure off the wrist by requiring more movement of the arm.

More than 50 percent of the users marked the Whale as "Uncomfortable or Very Uncomfortable" after using it...

Very interestingly, the subjects of Dr. Hedge's study reported that the mouse which caused the least stressful deflections -- the Whale mouse -- was also least comfortable. More than 50 percent of the users marked the Whale as "Uncomfortable or Very Uncomfortable" after using it, while none of the subjects reported that the Microsoft mouse was similarly uncomfortable. Clearly, there is still much to be understood with regards to the perception of comfort and physical damage.

More Tips for Safe Mouse Usage

A larger mouse isn't the only solution to reduce painful wrist problems. Here are some additional mouse-related tips.

• The mouse should be above the keyboard, slightly above the natural position of the elbows when the arms are relaxed.
• Learn to use keyboard shortcuts, which can significantly reduce the need for the mouse. In Windows 98, look in the Help index under "keys, shortcut". In MacOS 8.5 or 8.6, open "MacOS Help" from the Help menu and select "Shorcuts and tips", "Keyboard shortcuts".
• Use a good mousepad that encourages accurate mouse tracking. Repeated lifting & shuffling of the mouse in an attempt to correct bad tracking is frustrating and dramatically increases your wrist stress. I recommend the 3M Precise Mousing Surface.
• A cordless mouse, such as the Cordless Mouseman from Logitech, can reduce the frustration and stress involved with tugging and moving the mouse cord.
• As always, take time to relax and stretch when engaged in any intense activity.

For more information, consult the following information sources:

• Alan Hedge, Ph. D.
  The man who did the study.
• Carpal Tunnel Syndrome
  An explanation from Orthopedic Medicince Guide Jonathan Cluett.
• Carpal Tunnel Syndrome Net Links
  From About.com Neurosciences Guide Richard Schuerger.
• Contour Design
  This mouse manufacturer makes ergonomically designed mice in 5 right-hand sizes and 3 left-hand sizes, with products to support all computing platforms.
• Cornell Mouse Report
  Downloadable copy of Dr. Hedge's report; requires Adobe Acrobat Reader.
• Dr. Malka's Orthopaedic Pages
  Excellent summary of carpal tunnel syndrome, along with preventative exercises that minimize the probability of damage.
• Humanscale
  Unfortunately, a very uninformative home page.
• Input Devices, Keyboards
  Links to all the best keyboard makers, and links to RSI support information.
• Input Devices, Mice
  Many many links to makers and sellers of mice and related pointing devices.
• Is a Little Mouse Hurting You?
  New York Times article by Lisa Guernsey.
• Keyboard Alternatives & Vision Solutions
  This keyboard vendors caters to those with special needs. They've got dozens of alternative & unusual keyboards & pointing devices. It's one of the best resources on the web.

Suffering from RSI? Let us know on the Computer Peripherals Forum.

Previous Features

All text by Rick Russell.

http://peripherals.about.com/library/weekly/aa011599a.htm?terms=carpal+mouse

10 Tips for Using a Computer Mouse

The following tips should help you avoid a mouse-related musculoskeletal injury. The same posture principles apply to other input devices (e.g. trackball, touchpad, pen, digitizing puck etc.).

1. Mouse Grip - don't throttle your mouse (it's already dead)! Hold the mouse gently to move it over a mousing surface.
2. Mouse from the Elbow - don't skate or flick the mouse with your wrist. Make controlled mouse movements using your elbow as the pivot point and keep your wrist straight and neutral.
3. Optimal Mouse position- sit back in your chair, relax your arms then lift your mousing hand up, pivoting at the elbow, until your hand is just above elbow level. Your mouse should be positioned somewhere around this point. Don't use a mouse by stretching to the desk or out to the side of a keyboard. With a flat mouse platform, position this 1-2" above the keyboard and over the numeric keypad if you are right handed - you can easily move it out of the way if you need to access these keys. With a downward sloping mouse platform, position this close to the side of the keyboard so that you can use the mouse in a neutral wrist position. Position adjustable mouse platforms are commercially available (e.g. Humanscale, Proformix, Flexrest, 3M etc.)
4. Protect your wrist - if you look at the anatomy of the wrist it is curved away from any contact surface (you can easily see this by resting your hand/arm on a flat surface - you'll see light under the wrist and can probably even pass a thin pen under this). The forearm is shaped liked this for the wrist to remain free of surface pressure contact.
5. Avoid restricting circulation - For may people there are exposed blood vessels near the skin at the wrist, which is where the pulse is often taken. Any pressure in this region will disrupt circulation into the hand and this will increase the risks of injury.
6. Don't use a Wrist Rest - research has shown that using a wrist rest doubles the pressure inside the carpal tunnel, because the floor of the tunnel is a more flexible ligament that transmits external pressure changes directly into the carpal tunnel (the roof of the tunnel is bone so the pressure doesn't get transmitted on through the hand). Indeed, one test for carpal tunnel syndrome (CTS), know as Tinel's sign, simply involves tapping on the palmar surface of the wrist, which is enough to cause tingling and numbness in someone developing CTS.
7. Avoid Restricting Arm Movement - with a softly padded wrist rest, especially one that is rounded, or a soft chair arm rest the forearm becomes "locked" into position and this encourages people to make mouse movements by flicking the wrist, which also increases intracarpal pressure.
8. Keep the Mouse Free Moving - The base of the palm of the hand is the part of the body designed to support the hand when resting on a surface. For keyboard use a broad palm support is best. However, mouse use is different to keyboard use. With a keyboard the best posture is for users to float their hands over the keyboard when typing and then to rest on the palm support in microbreaks between typing bursts. You can use rest-breaking software (e.g. Magnitude ErgoManager, Break reminder etc) to help track and advise on your mouse use. With mousing this doesn't happen. A mouse is used by moving it's location over a surface, and resting usually occurs when mouse movements stop but with the mouse still being held in the hand. Mouse movements should be made using the elbow as the pivot point, not the wrist. Anything that impairs free movement of the forearm/hand and mouse will increase injury risks.
9. Mouse shape - choose a mouse design that fits your hand but is as flat as possible to reduce wrist extension. Don't use a curved mouse. Use a symmetrically shaped mouse. Consider a larger mouse, such as the Whale mouse or the Perfit mouse, that encourage arm rather than wrist movements.
10. Load sharing - if you want to load share between your right and left hands, that is using the mouse for some of the time with each hand. For this you need to choose a mouse platform that can easily be configured to the left or/and right, and a symmetrical shaped mouse that can be used by either hand.

Other input devices - whether you choose a different mouse design, a trackball, a joystick, a pen, a touchpad or some other input device, make sure that your position this comfortably, and that your wrist is in a neutral position when using the device. Personal favorite is the Fingerworks  iGesture Pad (I do work with this company)

Summary recommendations:

• Best arrangement for a mouse is a platform over the number keypad and just above the keyboard. 
• Good arrangement is a pad on an angled platform to the side of the keyboard. 
• Poor arrangement is a flat surface to the side of the keyboard 
• Worst arrangement is on the desk out to the side of the keyboard.

Other input options that don't cover the numeric keypad

If you needs to frequently use the numeric keypad consider the following:

• a platform that incorporates a touchpad into the palmrest (e.g. Proformix Intellitray) 
• an angled mousepad close to the side of the keyboard (e.g. Humanscale platform; Flexrest platform)
• a keyboard that has a touchpad built into the keyboard (e.g. Crystal vision; Cirque smooth cat).

More information on our Mouse research studies.

NOTE: Inclusion of links to manufacturer and product web sites is provided for user convenience and does not constitute endorsement of these products by Cornell University.

Send comments or suggestions to Professor Alan Hedge.

Note that all materials on this page and web site are copyright and may only be copied or distributed for nonprofit educational purposes without permission.

© Professor Alan Hedge, Cornell University, content last updated March 20, 2007

It also appears that mouse users are more likely to rest their arms on higher platforms such as desktops or the adjustable mouse pad, than they are on low platforms like the conventional tray.
 

Shoulder Muscle Activity:

• For both typing and mouse use the negative slope keyboard tray led to the lowest trapezius muscle activity of the three positions. There did not appear to be any affect of keyboard type (CK vs MS) on trapezius muscle activity.
• For both typing and mouse use the negative slope keyboard tray led to the lowest front deltoid activity. The difference was small and probably not significant for typing. The difference was much more pronounced for mouse use, front deltoid activity for the negative slope keyboard tray was only about half of that for the other two position treatments.
• For both typing and mouse use their was no statistically significant difference in mid-deltoid activity across conditions.
• There was no significant difference in mid-deltoid activity between conditions, however, there was a trend for slightly higher activity with the adjustable mouse pad. This suggests that users were working the mouse more with their upper arms during this condition. It also suggests that further benefits may occur with a mouse pad that is both location and height adjustable.

Wrist Movement - Mouse Use

• Mean wrist extension was much higher with the mouse on the conventional tray (average of over 25 degrees). Mean wrist extension was lowest with the mouse on the desk (under 8 degrees).
• Mean ulnar deviation was highest with the mouse on the adjustable mouse pad (over 18 degrees), because the mouse was closest to the body (the MS mouse shape encouraged ulnar deviation when the arm was relaxed and not abducted). Mean ulnar deviation was lowest with the mouse on the conventional tray (under 8 degrees), but in this posture the arm was abducted and wrist extended.
• Data on the percentage of time spent using the mouse in a neutral vertical posture show that the desk produced a neutral posture more than 50% of the time. The conventional tray produced a neutral posture less than 5% of the time. The adjustable mouse pad was between 20 % and 30%.
• Data on the percentage of time spent using the mouse in a neutral horizontal posture show that the adjustable mouse pad produced a neutral posture less than 20% of the time. Both the desk and conventional tray led to neutral postures between 38% and 65% of the time.

Cursor Positioning

Wrist posture was strongly affected by the three position conditions used in this study. The conventional keyboard tray with the mouse pad on the right side of the tray led to much higher wrist extension values than the other two conditions. As was previously mentioned, the high extension values are probably due to users having to reach down and out to the right in order to the reach the mouse on the conventional tray. Reaching down to a flat platform would require the hand to work with the wrist extended.

The adjustable mouse pad led to more ulnar deviation values than the two other conditions, which is probably due to the close proximity to the adjustable mouse pad to the user's body. With the mouse design tested, pointing the mouse straight ahead with relaxed arms requires users to ulnar deviate their wrists in order to manipulate the mouse. The desktop fared the best as far as wrist posture was concerned, but this also produced higher neck and shoulder strain. Different mouse designs should be tested.

Shoulder muscle activity was also strongly affected by the three mouse position conditions. The trends are the same as for typing. The adjustable mouse pad led to much lower trapezius and front deltoid activity, there was no significant difference for mid-deltoid activity. Shoulder muscle activity generally was lower for the adjustable mouse pad position because this position allows users to hold their arm close to their body instead of reaching up to the desk or down to the side for the conventional tray.
 

During cursor positioning ulnar deviation was higher for the adjustable mouse pad, but this may be a consequence of the mouse designs that were tested.

 

Cornell University Ergonomics Web

Mouse Use and Shoulder Strain

Much attention has been given to the ergonomic design of the mouse, yet virtually no research has been conducted on where the mouse should be located. Recent concerns that sustained mouse use can increase risks of CTDs is prompting reexamination of the optimal location for mouse use.

This page describes surface EMG results from a preliminary study of the effects of the horizontal location of the mouse on shoulder muscle (right deltoid) activity. All tests were done with a Microsoft mouse on an adjustable position mouse platform that was 27.5 inches above the floor.

For each trial the right shoulder abduction angle was set, using a goniometer, and the mouse platform position adjusted so that the mouse was positioned in the center of the platform and straight ahead of the forward pointing forearm. For each trial the subject moved the mouse from the central position to the top right corner of the mousepad, and then around the perimeter of the pad in a clockwise direction to each of the four corners of the mousepad four times in succession. Surface EMG measures (raw signal and rms) were taken using the Flexcomp system. Recordings were taken for the right arm at 10, 20, 30, 40, 50, and 60 degrees abduction, and also for mouse use on the desk top.

Results were dramatic, showing almost a 1:1 linear increase in EMG activity with increased shoulder abduction. These results are summarized in a downloadable .pdf file (readable using Adobe Acrobat - http://www.adobe.com).

	Download this Mouse Research result
	Download a Study of Mouse Design and Wrist Posture

Top 7 Computer Mice

Guide Picks

Named for the cable sticking out the back like a little tail, the computer mouse is the most popular pointing device for today's computers and operating systems. Pick a mouse with features and style to meet your needs. Look for mice with long cables and dual PS/2 and USB connections. Consider an optical mouse for easy cleaning and low maintenance.

1) Microsoft Intellimouse Explorer Microsoft leads the mouse world with the Intellimouse Explorer, a truly well-designed optical mouse. Although it's got a few too many buttons (does anybody use all five?), the ergonomic quality is excellent and the optical tracking is absolutely accurate. Right-handed use only; lefties can try the symmetric Intellimouse Optical. USB and PS/2 connections.

2) Kensington Mouse-in-a-Box Optical If you're looking for a basic optical mouse at a good price, the Kensington Mouse-in-a-Box is a great choice. I've recommended their products to dozens of users over the years; Kensington mice are reliable and cheap. This PS2/USB mouse is also Mac compatible, and Kensington's excellent Mouseworks drivers work on all platforms, including MacOS X.

3) Logitech MX700 Cordless Rechargeable Mouse If you're worried about the long-term cost of feeding alkaline batteries to your cordless input devices, check out the Logitech MX700. It's a wireless mouse with a built-in rechargeable battery and a receiver with integrated charging cradle.

4) Keytronic Lifetime Mouse Keytronic's LifeTime mouse is the most reliable non-optical mouse you can buy. It detects motion with two oblique disks pressed against the mousing surface. I've been using my Lifetime mouse since 1998, and it still works great! Manufacturer's Site

5) Kensington PocketMouse The Kensington PocketMouse is a pint-sized optical mouse for the laptop user. The USB cable retracts into the body of the mouse of easy storage and no tangles when packing and unpacking on the road.

6) 3M Renaissance Mouse 3M's ergonomic Renaissance mouse has a clever handle-like design that allows you to point with your hand in a more vertical position. Available in two sizes for small/medium hands and large hands. USB connector with PS/2 adapter.

7) Saitek Optical Mouse Pro You might look at the Saitek and think that it's just another optical mouse. Well, it is just another optical mouse, but it's got a blue LED on it that BLINKS when you receive e-mail with Outlook/Outlook Express. PC only, of course.

~ Rick Russell

Related Guide Picks   •  Alternative Pointing Devices •  Keyboards   Related Resources   •  Big Mouse, Less Pain? •  Mouse History

Mice and Keyboards Guide picks

Master list of links for computer mice, keyboards, trackballs, trackpads, and other input devices.

Top Picks: Alternative Pointing Devices Is the old mouse giving you a wrist cramp? If so, you might benefit from one of these fine mouse alternatives. Top Picks: Computer Mice Tired of the lame mechanical mouse that came with your computer? Check out this list of high-tech, ultra-realiable upgrades to your crufty old mouse. Top Picks: Keyboards Some of the best and oddest ergonomic and specialty keyboards. Alternate Pointers - Vendors Links to vendors of trackballs, trackpads, light pens and other alternate pointing devices. Keyboards - Info Links to keyboard articles, information, help and FAQ lists. Keyboards - Vendors Links to manufacturers, vendors and resellers of keyboards. Mice & Mousing Accessories - Vendors Links to computer mouse and mouse accessory (mouse pads, ergonomic aids) vendors, resellers and manufacturers. Mice - Info Links to computer mouse articles, features, and reviews.

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