That depends on what your expectations for crank tables are. If you want it to travel quickly from a seated to a standing height, then yes, they are very slow. But for making a small 1" or 2" adjustment a few times each day or week, or for adjusting 3" or 4" between shifts, it takes perhaps ten of fifteen seconds-not too slow at all.

It's important to understand what you want. If you are trying to encourage employee movement, don't make the mistake of thinking that rapidly moving from sitting to standing positions is the only movement alternative to sitting.

Movement is what people need. Leg movement in particular gets "the muscle pump" moving blood back to the heart, keeping workers alert, and healthy. There are many ways to accomplish leg movement; standing is only one of them. Seated workers can also stretch their legs under the table, or rock back and forth in a passive ergonomic chair. Movement includes a quick trip to the rest room, copy machine or water fountain. Standing isn't necessarily healthy for workers required to engage in static tasks; in fact, static standing can be worse than static sitting.

We have observed that standing VDT operators experience leg muscle fatigue if they stand for longer than a few minutes. Tiring leg muscles tell the body it's time to sit, and most workers at standing stations resume seated postures for the vast majority of their day, occasionally walking to take a break, or often stretching their legs under the desk.

Multiple movement options are particularly important in office settings when walking to the copy machine or supply room is not possible. Sometimes workers are tethered to their phones with telephone headsets, to their computers by deadlines, or for some other reason can't leave their VDT display for an instant. In these cases, any movement is desirable: the more options workers have, the better.

Be alert for adjustable desk features that actually limit movement: toe stubbing central support columns or knee and shin banging cross bars.

Depending on whose product literature you read, this can be a very confusing subject. Many AKP manufacturers, and plenty of adjustable table manufacturers claim their products have a sit-to-stand range, but do they? What is the "sit-to-stand" range anyway?

First, what is the seated range? The ANSI Standards (ANSI/HFS 100-1988) tell us that adjustable seated height keyboard platforms should cover a 23" to 28" range, even though their own anthropometric data for 5th% females and 95th% males suggest a broader range--21.1" to 30.8". The ANSI standards didn't address standing height ranges in 1988, but that information may be included in the 2000 update.

Bodyspace, Anthropometry, Ergonomics and Design., published in 1986, reports similar information. For 5th% females and 95th% males the seated elbow height range is 22.8" to 32.4." However, Bodyspace also included standing height ranges. For 5th% females and 95th% males the standing elbow height range is 38" to 48".

Added together, the sit-to-stand range that fits the 5th% female and 95th% male is approximately 23" to 48"! Adjustable desks that encompass or approach these ranges will fit more people more often.

Ideally, you could use both! If we sit at a desk all day, our arms need support. On average, arms weigh between 8 and 14 lbs. each, and something has to hold them up. Our shoulders do a terrific job, but like anything else, they need a break. If you spend a few hours in the static postures that computer work demands, you might lean on the desk or rest your palms on the desk edge when you type.

In moderation, there's usually nothing wrong with this. Except most of us don't work in moderation at a computer! Thanks to multiple on-line computer functions like E-mail, FAXing, etc., we work for longer periods without a change. You find yourself resting wrists or arms on desk edges, or holding your shoulders in a shrugged posture all day. That leads to problems.

A cockpit shaped work surface and a chair's adjustable armrests, when adjusted to the right height, can effectively unload this arm weight and help up us maintain comfortable postures.

A problem arises when the chair's armrests interfere with the cockpit shape. Some times you lower the armrests, or use a separate computer task chair. Some relatively open cockpit shapes don't constrain the chair but still supports the worker's arms. Try these guidelines:
Adjustable cockpit desks best support dedicated, computer intensive tasks. If you tend to stay in front of your computer most of the time--writing, data entry, designing, etc., the cockpit shape offers complete surround-the-worker support where you need it.

Adjustable armrests best support frequently interrupted work or multi-task work. If you constantly roll or swivel in your chair from one part of your desk to another, or you find yourself in long meetings or phone calls, these arm supports go with you, no matter where you work in your office.

The negative tilt feature on AKPs is designed to help people maintain more neutral wrist postures. Whether or not negative tilt should be used depends on the work, the worker, and the keyboard being used. First, understand why many keyboards have a positive slope--so you can see the keys more easily! Keyboard features like slope must balance competing parts of our anatomy, in this case, our eye/neck comfort with our wrist comfort. When using older style traditional keyboards with a steep positive slope, a negative tilt is probably a good idea. Granted, in upright postures or slightly forward leaning postures, the more positive the keyboard slope, the greater the wrist extension, and thus potential for discomfort. But in slightly reclined postures, or with newer style conventional keyboards, your wrists are already in neutral alignment without any negative tilt at all.

AKPs are often a fine solution. They are usually inexpensive and easy to install, but they solve only part of the problem. They adjust keyboard height. Period. And they have significant trade-offs. Try this: get comfortable at your computer work station, then move back 12" to 18" (the distance an AKP pushes you away from your desk). Notice:
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· AKPs do nothing for the VDT height, a crucial element in the ergonomic office equation.

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· AKPs cause you to reach an additional 12" - 18" for you phone or other work areas, forcing you to twist and bend your back much more.

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· AKPs reduce your easily accessible work space by up to 50%, forcing you to either twist and bend, or crowd all your work materials toward the work surface edge, wasting valuable work space.

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· AKPs may cause uncomfortable thigh and knee contact pressures, depending on how you sit.

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· AKPs often bounce and wiggle while you key or mouse, which can cause distraction and entry errors.

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· AKPs can push you and your chair so far away from your desk that you are in an aisle way or someone else's work area, or you can't comfortably open your own file drawers.

If all you need is limited height adjustment, AKPs are a fine solution. But they compromise a work station's symmetry. On the whole, AKPs are only a partial solution that can create more problems than they solve. Many AKP users simply remove them after a few frustrating weeks!

Yes, but then you can't make any changes to suit your own daily or weekly needs. For example,

1.
In the morning you are taller. All day long the earth's gravitational forces compress your spine, and you become a bit shorter. At night when you sleep you gain that height back. This is why you sometimes adjust your car mirrors when you drive to work in the morning, and readjust them for the drive back home! As you grow taller and shorter, your elbow and eye heights change, and this requires small changes in the work surface height to keep you comfortable.

2.
You might want to stand at your desk for a short time, but you don't want to slump over your desk--that would be bad for your back posture. You may be able to raise an adjustable desk to suit your standing comfort needs

3.
When you sit upright your elbows and eyes are one height; as you recline those heights lower. Nearly everyone reclines a little, especially towards the end of a day, and desks should lower with them.

4.
When you wear shoes with different heel heights, your elbow and eye heights change too!
And those are just the reasons you should make adjustments. If other people use the desk, they have the same concerns, but different height needs. End-user adjustable work surfaces make sense because they give you the same immediate comfort control that a good ergonomic chair gives you.

Because your most comfortable typing height is not the same as your most comfortable viewing height. Imagine working at a laptop computer (a convenient, portable, ergonomic disaster area that places typing and viewing heights very close together). If your arms are comfortable, your neck is probably bent forward. If your neck is comfortable, you are probably shrugging your shoulders. Ouch!

Here's the way most people should work to stay comfortable:

1.
When you are seated comfortably, your keyboard should be at approximately elbow height.

2.
Position your VDT so the screen top is at or slightly below eye level.

If your VDT is small (10", 12") you might need to raise it.

If the VDT is large (15", 17", 21"), or if you wear bifocal glasses and view the screen through the lower lens, you might need to lower it.

Yes, but many people "multi task" when they work at a desk. They work on a computer over here, and the phones over there, and papers somewhere else. They'd need three or four footrests, and probably trip over them. As you move from one part of the desk to another, notice how your feet need contact with something both to move you and to keep you comfortable once you get there. If you have a very tiny desk, or work in only one area of your desk, a footrest might be all you need to correct a desk that is too high for you. Footrests are also useful for occasional foot placement variety. Use the floor as much as possible to support your feet. Unlike a footrest, the floor is large, stable, and it doesn't move around. Footrests are good, but a floor is even better.

It's not that easy. People have a particular low back curve they like to maintain, and many experience discomfort if they lose or exaggerate that curve. That "perfect posture" curve is best supported when we sit with our feet on the floor, feel uniform weight pressures along the chair seat, and feel comfortable low back support. We lose the curve when we sit too low, e.g., when our knees are higher than our hips. That happens when we adjust a chair to fit a low desk. We exaggerate the curve when we sit too high, e.g., when we perch on the edge of a chair seat so our feet still touch the floor. That happens when we adjust a chair to fit a desk that is too high.

Well fitted office chairs are only part of the picture in today's computer office. They help you maintain neutral low back postures. Chairs do little to help your wrists, elbows, shoulders, and neck stay in neutral postures, yet upper extremity and neck disorders are rapidly overtaking lower back pain as the leading cause of lost work days, not to mention productivity draining discomfort! Think about it: as you reach for your phone, stapler, keyboard, or mouse, or when you look at VDT screens or copy, you compromise your arm and neck postures unless these reach and viewing targets have been placed just right for you, i.e., on an adjustable work surface. Try this: sit comfortably in your chair. Unless your desk height is approximately your elbow height, it's too high or too low for you. Notice how you slump or shrug when you work at your desk? Now reach for a telephone or a reference book on the desk. Does your chair protect your "perfect posture"? Probably not. When work surfaces fit workers as well as chairs do, and their equipment and papers are placed where they can comfortably see and reach them, then all the joints-low back, wrists, elbows, shoulders, and neck--are in neutral postures. Without adjustable work surfaces, adjustable chairs are much less effective.