Important Features in Evaluating Ergonomic Keyboards

TROUBLE CHOOSING AN ERGONOMIC KEYBOARD?

So you've decided to improve both the comfort and productivity of your computer tasks. You already have a comfortable, adjustable chair and a thin, adjustable keyboard/mouse tray (any wrist rest should be removable). The next step in your workstation overhaul will be an adjustable ergonomic keyboard, one that won't break the bank, is effective, yet has a minimal learning curve. But there are so many products on the market! How do you decide which product is best?
Ergonomic Design Principles For Computer Keyboards
Keyboarding is a complex task, so it isn't easy to design a better computer keyboard. Any change intended to increase comfort can simultaneously decrease the speed or accuracy of typing and editing. For a product to be considered effective, it should improve both comfort and productivity. Certain general design principles are widely accepted as necessary (though not sufficient on their own) to create an effective ergonomic keyboard:
- Maintain neutral posture,
- Avoid awkward reaching for mouse,
- Avoid unnecessary force, vibration, and repetition,
- Minimize adaptation time,
- Adjustability should by simple and reproducible.

The final two design principles are recent additions to the list, but their importance has become better appreciated in recent years. These design principles are all discussed in detail below.
Maintain neutral posture
The objective of "neutral posture" is to avoid tense muscles that reduce blood flow, and constricted joints where nerves and tendons could experience unnecessary friction and pressure. Neutral posture for computer users is generally described as thighs and forearms parallel to the floor, with wrists straight (not bent upwards, outwards, or inwards).
An adjustable chair and keyboard/mouse tray can be configured to achieve forearms and thighs parallel to the floor (in some cases a foot rest may also be needed). A keyboard which elevates the thumbs allows forearm muscles to be relaxed. Wrists are kept straight with a central split in the keyboard and integrated palm supports (also discussed in detail below).
Relaxed forearms and good blood flow
A critical feature of a good ergonomic keyboard is promoting relaxed muscles in general, and relaxed forearm muscles in particular. Tense muscles are doing work but not allowing good blood flow, and they are not contributing to productivity. Relaxed forearm muscles are achieved by elevating the thumbs through "tenting" (raising the middle) of the keyboard. The tenting angle can be either fixed or adjustable, as long the optimal tenting angle of 10-20 degrees (Zip et al, 1983) is achieved to provide virtually complete relaxation.
In the "optimal tenting range," the keys are still easily visible (even a good touch typist occasionally takes a peek!), gravity still helps users center their hands and fingers over the home row, and the hands don't become so elevated that blood flow is reduced. A smaller angle (e.g. the 7 degrees provided by the Microsoft Natural keyboard) only provides partial forearm relaxation. An angle greater than 20 degrees does not provide greater benefits for most users, but can often make typing more difficult.
Relaxed neck and shoulders
Two design features can promote relaxed neck and shoulders. One feature is integrated, padded palm supports, preferably removable for those users who otherwise cannot get close enough to the keyboard. Resting the palms (not the wrists!) occasionally on a support allows the neck and shoulder muscles to relax, while the padded palm support also ensures that the wrist posture remains "neutral" and blood flow is maintained while resting.
The second way to relax the neck and shoulders while using a computer is with a keyboard that is split completely with a gap in the middle, so that the arms project essentially straight out from the body shoulders. In contrast, the most common split keyboard design employs a "V" split in the middle, with only the front of the keyboard separated. The popularity of this style is due in part to its inherently lower cost, and in part to the aggressive marketing of Microsoft Natural-style full-width keyboards. The small-footprint Kinesis Maxim and Goldtouch adjustable keyboards also offer this design style. While the latter two keyboards offer significantly more ergonomic benefits than the Microsoft Natural, none of these are the best at relieving neck and shoulders strain for most users.
The type of central split which minimizes neck and shoulder strain separates the keyboard into two alphanumeric sections, which are completely separated by a gap. With this design, the user's arms project more or less straight in front of the shoulders. Keyboards with this split style are available from a number of manufacturers (e.g Kinesis Contoured keyboards and other adjustable keyboards listed below). These other designs are typically more expensive, require more adaptation.
Avoid awkward reaching for mouse
Most computer users do more work (and create more strain) with their mouse than with their keyboard. This is especially true with a full-width ergonomic keyboard such as the Microsoft Natural, because the presence of an integrated numeric keypad combined with the central split makes it wider than a traditional keyboard. Thus right-handed mouse users (~80% of the population) must use their mouse far outside the optimal "in-front-of-the-shoulder" position.
Fortunately, it is easy to avoid this problem. Just select a small-footprint keyboard, one that does not have a dedicated numeric keypad section. Since majority of computer users do not frequently use a numeric keypad, a small-footprint keyboard provides a much better position for the mouse. Either an embedded numeric section (like that found on laptop computers), or a separate keypad that can be moved into position (on either side) when needed, will meet the needs of most computer users without requiring awkward reaching for the mouse. A keyboard tray with room for the mouse at the same level also is an important tool for reducing mousing strain.
Avoid unnecessary force, vibration and repetition
Force and vibration are normally thought of as injury risk factors in industrial jobs, but typing can create constant impact by the fingers on the keys, which requires force to press the keys and creates significant vibration at the point of impact at the end of each keystroke.
While it is hard to know how to judge a keyboard based on force and vibration factors, there are several features which can minimize force and vibration. Of course it is obvious that key force should be low, but if it is too low, the impact at the end of each keystroke may increase. Switches with "over-travel" (the ability to continue moving after making electrical contact) can greatly reduce impact. Unfortunately, the widely-used rubber-dome switches cannot provide much over-travel compared to the more expensive mechanical switches used in premium ergonomic keyboards like the Kinesis Contoured keyboard family.
Repetition is a risk factor you can do something about. Highly repetitious data input work can be "automated" using macros (key sequences) provided by your software, or by some programmable keyboards, keypads, or foot switches (e.g. Kinesis Contoured keyboards, Savant keypads, Savant Elite foot switches). Not only does your work get done faster, you are making less movements (which is reducing a certain amount of force and vibration as well).
Minimize adaptation time
While some highly effective ergonomic keyboards do require significant adaptation time, just because a product requires adaptation doesn't mean that it will be effective, and vice versa. Individual computer users will have different objectives when it comes to performance versus adaptation.
The best product for a multi-user workstation, or for someone without serious RSI (Repetitive Strain Injury) problems who isn't willing to experience any "down time" will be a minimal-adaptation product like the Kinesis Maxim or KeyOvation's Goldtouch keyboard. However, a computer user willing to trade a few days of reduced output for a lifetime of greater comfort and productivity will probably be happier with a more aggressive (and more expensive) design such as a Kinesis Contoured keyboard.
Provide simple and reproducible adjustability
Where a product offers adjustability, it should be easy to accomplish (conceptually and physically) or users won't make the adjustments. Also, the product should have safeguards to discourage inappropriate adjustments. Otherwise users could inadvertently create a configuration that does more harm than good.
The most difficult feature to provide in an adjustable keyboard is variable "tenting," so not surprisingly, this feature exhibits the greatest variability in its simplicity and reproducibility between different designs. It seems that tradeoffs must usually be made between easy and reproducible "tenting" adjustments, and a greater range of "tenting" adjustments. As with adaptation requirements, different computer users will decide this matter differently because of differing needs. However, experience has shown that even if extreme tenting adjustments are possible, most users don't seem to use these settings, perhaps because of the documented "optimal typing zone" of 10-20 degrees for tenting (Zip et al, 1983). Experience has also shown that if adjustments are not very simple and reproducible, users won't take advantage these features at all.
CHOOSING A KEYBOARD
Now that you are familiar with the design principles of an ergonomic keyboard, you need to select the one that will best meet your needs for budget, effectiveness (comfort, productivity), and adaptation time.
While personal preference plays role in weighting the various ergonomic design principles listed above, your decision will only be a "guess" until you have actually used the product for several weeks or a month. So be sure to purchase from a company with a no-charge return policy in case you need to make another choice.
If you are still reading this article, you are serious enough about your comfort and productivity to rule out the large array of Microsoft Natural keyboards and their clones. While such keyboards work adequately for most computer users, those seeking optimum performance will virtually always be happier with a more sophisticated product. The fixed front split requires several hours of adaptation for most users and can't be tuned to fit your shoulder width, while the 7 degrees of "tenting" provides only partial relaxation of forearm muscles. Furthermore, the built-in keypad on the right forces right-handed users to place the mouse even further away than with a traditional keyboard. How ergonomic is that?
Best performance or no learning curve
Next consider whether you would accept reduced productivity for at least 2-3 days in exchange for achieving the absolute best comfort and productivity. For most computer users, this is the single most important factor in choosing a premium ergonomic keyboard. In this article we will discuss your choices if you opt for the no-adaptation route. In a future article, we will explore your options if you really want the highest performance possible and are willing to experience a significant adaptation period in order to achieve that objective.
Most computer users who are not seriously injured with RSI will find the best balance of comfort, productivity, and cost in a small-footprint adjustable keyboard that has a key layout very similar to the traditional keyboard. These tend to be priced in the range of $120-150, whereas the more exotic choices tend to cost twice as much or more. A well-designed small-footprint, adjustable keyboard can virtually eliminate an adaptation period if the "standard" key layout is largely retained. The two most popular examples are the Kinesis Maxim and the KeyOvation Goldtouch adjustable keyboards.
Kinesis Maxim vs KeyOvation Goldtouch
While the Kinesis Maxim and the Goldtouch adjustable keyboards share many common features, there are distinct differences that can affect how effective each would be for any individual user. Both are narrow (using embedded numeric keys like on a laptop computer), allowing for optimal placement of the mouse, and separate keypads are available for both. The most obvious differences are that the Maxim includes integrated, padded (but removable) palm rests and offers a reproducible adjustment mechanism covering the ranges most often desired. In contrast, the Goldtouch keyboard offers a greater range of height adjustment for users with special "tenting" needs, although the adjustment mechanism is not well suited to creating reproducible settings and achieving a stable position requires some trial and error. Another difference is that the Maxim has a somewhat more standard arrangement of editing keys.
Optimum "tenting" settings. Many persons evaluating ergonomic keyboards mistakenly believe that the best tenting is the highest tenting, essentially a hand-shake position. If you were simply shaking hands with your keyboard, that would be the best position, but typing is much more complex than that. Independent research has shown that when performance and comfort are co-optimized, the ideal tenting range is 10-20 degrees for most computer users (Zip et al, 1983). The Maxim adjustable keyboard offers 10 and 16 degrees of "tenting," versus only about 7 degrees for the Microsoft Natural keyboard. The Goldtouch keyboard offers a continuous range of tenting angles up to approximately 30 degrees (significantly exceeding the published performance-comfort range of Zip and colleagues).
Importance of palm supports. Two issues are ignored by many ergonomic keyboards, and especially adjustable keyboards, are wrist extension and upper body muscle tension. While it is technically difficult to combine all the important ergonomic features in an affordable product, fortunately a single well-designed feature can do the trick. That feature is the presence of integrated palm supports. For maximum effectiveness. it is important that these are padded, and removable.
Ease and reproducibility of adjustments. One observation we have made (and which is supported by the unpublished results of independent research studies) is that many computer users with adjustable keyboards don't take advantage of available adjustments to create an optimized work station. If the adjustment mechanism isn't instant, easy, and reproducible, we believe users are deterred from adjusting at all. Also, if the range of possible adjustments exceeds the generally accepted "performance and comfort" zone, users may create configurations which are worse than if they didn't have an ergonomic keyboard.
Standard arrangement of editing keys. The Goldtouch general-purpose keyboard moves many of the editing keys (Home, End, PageUp, PageDown) on the left side of the keyboard while leaving Insert and Delete on the right side.. While this change is not inherently bad, it reduces productivity during an adaptation period, right-handed users may not be as skillful editing with their left hands even after they have adapted. Of course someone who needs to reduce their right-hand usage, or a left-handed person, may find this change advantageous.
Other adjustable keyboards
There are other adjustable keyboards which may meet the needs of some individuals better than the two profiled above. Some are more adjustable, others less but with more extreme positioning of the keys. In general these will be more expensive, and will require more adaptation. Some better known alternatives include the Comfort, DataHand, orbiTouch, Pace and SafeType keyboards.
Reference: Zipp, P., Haider, E., Halpern, N., and Rohmert, SV.(1983), Keyboard design through physiological strain measurements. Applied Ergonomics, 14(2):117-122.