Freakgronmics Chair Question
July 21, 2006 8:04 PM   Subscribe

Ergonomics, part kajillion. I do have a few particular questions regarding chairs.

I have had wrist and forearm pain for the last 6 months. It's actually been getting somewhat better since I've been working on my posture and taking occasional breaks. Still quite problematic, though. I've just purchased a Kinesis keyboard on the good word of some members here. To round out mending my ways I'm looking for a new chair, and thus, my questions:

1.) Does it matter if I get a chair without arm rests? They always seem to get in the way when I use the mouse (I'm tall and I've got sort of freaky long arms). Using a mouse I always end up lifting my elbow higher to clear the arm rest. It's agonizing to use a mouse due to that bad habit. Do arm rests provide any benefit that I should be aware of?

2.) I'm having difficulty figuring out how high I should position a chair. It seems like I can never quite get the keyboard tray right, the optimal position seems to actually be coexistant in space with my thighs -- again, freaky long arms and legs, but shortish torso. What to do, what to do? My current solution is unsatisfactory - I use a cushion on the chair to boost myself up a bit so that my thighs slant downward a few degrees and there's room to lower the keyboard. I end up with my legs falling asleep though, and it leads to slouching sitting like that.

3.) I think my arm pain is aggravated by the way I sleep. I usually sleep on my side, rolling over even if I fall asleep on my back. Some mornings when I wake up, I know it's going to be an extra wretched day from the way I've slept. How do I learn to stay asleep on my back all night?

I am trying to get in with a PT or OT, to get a consult on posture and work habits. I've got to get in with my PCP first and then the wait is long to see the OT after that. I'd like to get a chair sooner rather then later - my old one is seriously about to disintegrate and tip me on to my ass, and has no real back support. So, advice for the interim?
posted by voidcontext to Health & Fitness (8 answers total) 4 users marked this as a favorite
 
So, we've got 3 numbered questions, and 1 catchall wrap up. OK, then, here's my take:

1) Armrests definitely take the weight of your arms off your shoulders, neck, and upper body when you are reading. If your tasks are essentially long duration, head down data entry, armrests might be less important, but for the average office worker or student doing a combination of normal reading and typing, they are helpful. Some chairs have adjustable arm rests, and on one high end chair I had (by Bodybilt) they were not only height adjustable, but swung out of the way easily.

2) Your chair has to be adjusted to fit you. Once that is done, where ever you wind up height wise, is your starting point for adjusting your table/keyboard/monitor height. Most people find that it's tough to adjust their desk surface heights however, and take these as the fixed positions, and try to adjust their chairs to compensate, since the chair has all kinds of knobs and levers. But that doesn't work, as you're finding out.

Your knees need to be at a 90 degree angle when you're seated, and unless your shoe sole thickness changes radically from day to day, there will only be one "right" height for that, as determined by the length of your calves. So, your chair seat height should be set to whatever gives you a 90 degree knee angle, and that's it. You may be tempted to try to change the seat height if you feel pressure on the back of your thighs, but in a well designed chair, the combination of a seat pan with a waterfall front edge, or a seat pan tilt adjustment should eliminate any pressure points there.

Once your "base" is set, the rest of your working surface heights come from the dimensions of, well, you. It's easier to make these with adjustable computer desks, but frankly, if you don't mind using blocks or saws to adjust standard furniture as needed, you can make any desk "right" with time and effort. Your arms should hang naturally, and with your elbows bent comfortably at about 90 degrees, you find your desktop height. Your comfortable working surface height range for keyboards will not be more than +/- 3 inches from this height. You need to bring your desk or keyboard tray into this height range, if it is not already. Your monitor height obviously comes from your natural head height, but is usually comfortably 5 to 8 inches below your eye center height, for a normal 17 to 21 inch screen center, with a slight angle upward toward your face. You change the monitor height to achieve this with adjustments on the monitor base, or shelves or monitor stands.

There! Now you're ergonomic. Like they are at Berkeley.

3) I haven't a lot of advice about sleep training, although I've seen your same question asked here several times in the past weeks, with other responders repeatedly advising that a tennis ball sewn on the front of your shirt helps keep you laying on your back. Hearsay recommendation only. I personally sleep soundly on my stomach, like a happy baby.

Wrap up: In the next weeks, you could visit several office furniture places, and sit in chairs that have the necessary features and adjustments you need to be comfortable. Don't consider any that don't. Shop for a good chair, and you can find a good deal. Buy a quality chair with the features and fit you need, and don't look back. Work on getting your table/desk surfaces to the right height(s) thereafter.
posted by paulsc at 10:41 PM on July 21, 2006 [1 favorite]


I have just been through the process of working with an OT on my workstation setup, since a particularly bad RSI injury.

Her advice was that armrests were bad for 2 reasons:

1) Resting on an armrest compresses your forearms. This leads to reduced bloodflow, compression of the carpel tunnel etc., and all sorts of Bad Things happen from there. Don't rest your arms or wrists on anything whilst typing or mousing.

2) In my case, armrests on the chair prevented me from getting my chair under the desk, meaning I had to stretch to reach the mouse and keyboard, and causing me more problems.

You seem to be doing a lot of the right things. My hand therapist had me wearing a wrist brace at night to keep me from curling my hands up. I also sleep on my side or front. She said this isn't so much a problem as the curling up of hands and arms, and that it is important to sleep with your arms straight. This is mightily uncomfortable for me, but I notice the difference when I make the effort. She suggested things like wrapping a small towel around my elbows, and pinning it in place, to prevent me from bending at the elbow in my sleep.

The reason for keeping the elbow join straight was because the ulnar nerve was a problem for me on my left side, and the ulnar nerve runs through your elbow. Bending the elbow, or leaning on the elbow causes further compression of the nerve.

On my right side it is the median nerve which is bad, so this is where the wrist brace comes in. The median nerve runs through the carpel tunnel (at the base of your palm), and bending at the wrist further compresses the carpel tunnel.

If you have long legs, make sure your chair has a reasonable depth to the base (from the back of your knees, to your backside), or you may not be getting enough support. I had the opposite problem. With short legs, and a deep chair, I wasn't able to get my backside right against the back of the chair, and I was slouching and not getting the correct back support.

Without doubt, the most effective thing you can do, is the cheapest & simplest: take regular micropauses and breaks.

Good luck with your OT. If you want to talk further, feel free to email me.
Good luck with your OT.
posted by girlgeeknz at 11:50 PM on July 21, 2006


Armrests can really get in the way for some users. If you find this to be the case, don't use them.

the optimal position seems to actually be coexistant in space with my thighs

I have this problem too as my arms are disproportionately longer than my torso (which is still quite long). The Kinesis is a nice keyboard but it is so thick. One thing that will help is making the angle of your knees slightly greater than 90 degrees and make sure your keyboard tray has negative tilt.

I end up with my legs falling asleep though, and it leads to slouching sitting like that.

Well, that's not good. You need to get a seat pan that actually tilts itself.

I would say the three things that have helped me the most are (1) Workrave; (2) physical therapy; (3) switching from a right-hand conventional mouse to a left-hand Quill mouse; and (4) proper keyboard alignment. There are other helpful things that I've done but you need to take care of these first.

Let me repeat the first one: Workrave, Workrave, Workrave. It's free and very helpful. If you're using Mac OS X, there is a free equivalent. Everyone should use Workrave, even people without problems yet (they can just set the timers high).

Until you can get physical therapy, you might start with some stretching exercises. But DO NOT do the strengthening exercises on that page without a PT's approval first. If anything is painful, stop doing it until you can get professional advice.

Every medical professional I have talked to (a GP, a hand surgeon, a physical therapist, an occupational health nurse, and occupational health specialist physician) has thought that a hand brace while sleeping was contraindicated, although it did keep me from sleeping on my hands. I do not recommend it.
posted by grouse at 6:14 AM on July 22, 2006 [1 favorite]


Thanks for all the advice - to clarify, I do about 75% coding and about 25% video editing, so there is not much time I'm just sitting at a computer reading.

WorkRave looks really good, I have been using an egg timer but that program looks a bit more focused.

I'm going to print this thread out and head out to the office store and start trying out some chairs.
posted by voidcontext at 7:51 AM on July 22, 2006


Voidcontext, I have the same problems with chairs. Over the years, I've changed mice, keyboards, and chairs very frequently, but only changed desks twice. I recently discovered that the desk I've been using for the past three years is nearly 2 1/2" taller at the keyboard level than most standard desks. As a result I've been unnecessarily straining my wrist, arm and shoulder when using a mouse. I immediately bought a more conventionally proportioned desk.

I also bought a new armless chair. It's simple and cheap; you can find it at Offfice Max (item number 20212994), on sale for $30 right now and they'll deliver for free if you order over $50. This chair is also excellent for people who use a Wacom tablet and prefer to put the tablet on their lap as I do sometimes.

Wacom tablets are aslo a great investment. Between my Wacom and keyboard shortcuts, I hardly rarely need the mouse.

Also, the Microsoft Natural keyboard is really great. Best keyboard I've ever owned as far as comfort goes. It's also really quiet, which is a wonderful bonus.

Workrave is wonderfully helpful, too.
posted by LuckySeven~ at 8:23 AM on July 22, 2006


1) The arguments about armrests are infinite; I'm against them for heavy keyboard users.

2) What paulsc said -- your inability to adjust your chair and keyboard tray indicates a problem with the desk height/keyboard tray adjustability. The only keyboard platform I really like is the Banana Board which is pricey, very adjustable, and the platform itself is thin and minimally gets in the way of putting the keyboard where you want.

And definitely use Workrave or whatever to remind yourself to take regular stretch breaks.
posted by Zed_Lopez at 9:57 AM on July 22, 2006


I have a Banana Board which is great for the keyboard, but since I keep the keyboard at an angle the mouse just falls off. I had a flat piece of chipboard attached underneath my desk for a mouse platform in addition.
posted by grouse at 4:56 PM on July 22, 2006


Just a bit of followup:

I'm still trying out chairs - thank you for all the advice! I want to make sure to pick the right one, so I'm going to try some more expensive ones this week.

Also, Work Rave was an excellent suggestion, even though it doesn't have anything to do with chairs. I was using a timer before this to take breaks, but Work Rave is infinitely better.
posted by voidcontext at 8:37 AM on July 25, 2006


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