Great, thanks for the videos, especially #2.
So my first question is: does your chair go any higher, or your desk any lower? Notice that right now your keyboard is a few inches above the level of your elbows, meaning that to type you need to either reach your arms out quite a bit in front of your body with your elbows out to the side, or else flex your elbows to an acute angle and put some load on your biceps. If the chair and desk can’t be changed, that’s not the end of the world, but you need to account for that with keyboard placement/orientation. If you can’t change the chair, sometimes stacking something on top of it can be helpful. It’s kind of pricey for what it is, and it’s slightly silly, but I’ve sometimes enjoyed carrying this thing to coffeeshops where I plan to work for a few hours –
http://www.ergodepot.com/HumanTool_Balance_Seat_p/ht-balance.htm – which raises the seat height by maybe 8 inches, and encourages sitting with an upright back and a more open hip angle.
0. If you compare the Ergodox to a standard keyboard, you’re able to fix one big problem, which is keeping your wrists straight in the horizontal plane of the keyboard by separating the two halves, not turned out sideways (a.k.a. “ulnar deviation”, as the central position and rectangular shape of a standard keyboard encourages).
But you still have some other parts of your arms/hands that aren’t in the most neutral position.
1. Your arms are reaching a bit far forward, giving your arms/shoulders more work to do to hold up the weight. I’d recommend trying to bring your table a bit closer to your body, so that your arms aren’t quite as far forward, and then trying to relax your shoulders as much as possible, keeping them back and down rather than shrugging upward or forward. Ideally, you want to eliminate as much of the static load on your back/shoulder/arm muscles as you can.
2. Just like on a standard keyboard, your forearms/wrists are pronated almost to their limit (i.e. rotated so that the palms are pointed downward). The neutral rotation is something close to a vertical/handshake position, and there’s a pretty wide range of comfortable resting orientations, but pronated all the way is pretty stressful/uncomfortable. (This is one of the biggest problems with most non-split keyboards).
3. The front/back tilt of the keyboard is not aligned with the angle of your forearms. If you can’t change the chair height, I’d recommend lifting the far side of the keyboard up a bit (whether we’re talking about the Ergodox or a standard keyboard), until the horizontal plane of the keys is parallel to the plane of your palms/forearms. At your current position, far away rows of keys are annoying to reach for, because they’re effectively (compared to your arm angle) lower than the home row. Basically, the taller your table, the more tilted you want the keyboard, and vice versa; if the table is low enough, if you have a standing desk, or if the keyboard is on your lap directly, then even a slightly negative tilt, where the close side is higher than the far side, can be helpful.
4. Because of (1) and (3), you are resting your palm on the table to take some of the load off your shoulders. This makes it hard to keep your wrist straight.
5. (Maybe?) Your palm and first joint of your fingers are all kind of curved upward (i.e. in the opposite direction of the way they bend when making a fist). I’m not sure if this is comfortable for you, everyone’s hands are a little bit different, and you seem to have extremely flexible joints. Personally, I can’t even bend my hand into that kind of shape, and trying requires tensing several muscles to the extreme. I find that if I relax my hand, it naturally bends a bit the other way. Raising your palm/wrist a bit compared to your fingers might also put your thumbs in a more comfortable position. Right now they seem to be adducted a fair bit compared to a neutral resting position.
I’d recommend letting your hands sit loosely in your lap, and try to feel in your body how much muscle tension is required to hold your fingers/hands/wrists/arms in different positions. How much tension is there if you open your hand completely flat vs. how much tension if you make a fist, and various amounts of finger curl in between those extremes. How much tension if you rotate your palms all the way up vs. all the way down. Etc. In general, you want to keep your joints relatively neutral, because from a neutral/medium starting position, they have the most agility/flexibility to move. I find that my fingers work best when my wrists are within about a 5° angle to either side of neutral (but most people type with their wrists extended at a 20°+ angle). Similarly, I find that even a 15° tent angle for each half of the keyboard is a huge help compared to flat, though I prefer a steeper angle than that, like 30–45°.
Finally, I find that some of the physical keys on the Ergodox are out of easy reach, where pressing them would require turning my wrist side to side or reaching my whole arm; I try to map all the main functions I need (e.g. backspace, escape) to keys in very easy reach, and either ignore the further away keys or map them to uncommonly needed functions. (Actually, personally, I don’t like several design choices of the Ergodox, and I set it aside after using it for a couple months and have been using a mix of standard layout keyboards (including too much time on a laptop keyboard) and my own custom prototypes for the last year or so.)
Edit: actually one last final thing: try stuff for yourself and find something that works for you. Everyone’s body is a bit different, so don’t take any of our advice as gospel. And of course, posture/technique advice is only so useful. Just as important is to take a brief break to stand up and move and stretch a bit every 15 minutes (or at least once an hour), switch between different postures and tasks occasionally (e.g., when you need to think about a problem for 20 minutes, take a walk), and don’t spend too many hours every day sitting working. Also, get enough sleep, eat a healthy diet, get enough exercise, try to avoid too much work/family/relationship stress, etc. etc. All that standard “how to lead a sane healthy life” advice.
