Typing ergonomics: wrists, elbows, keyboard

Touch typing trains your fingers, but your wrists, elbows, and keyboard decide how comfortable those fingers still are after an hour of work. The most concrete numbers come from a study by Marcus, Gerr, and colleagues. They followed 632 newly hired computer users over time and linked their working posture to later neck, shoulder, hand, and arm symptoms. Its findings, as reported in the study’s summary, are associations rather than proof of cause and effect, but they make a good guide for setting up your desk.

Keep your wrists straight

The US Occupational Safety and Health Administration (OSHA) puts the basic rule into one sentence: “Your wrists should be straight and in-line with your forearms.”

Keir and colleagues put numbers on wrist angles. They measured the pressure inside the carpal tunnel, the narrow passage through the wrist, in 37 people at different hand positions. From this they derived limits: the angles at which the pressure reached 30 mmHg in 25% of the people. For bending the hand up, the limit was 32.7°; for bending it down, 48.6°. Sideways, the limits were smaller: 21.8° toward the thumb and 14.5° toward the little finger.

These are limits, not targets. You do not need a protractor at your desk. Look at your hands from the side and from above: each hand should continue the line of its forearm. If it doesn’t, adjust your chair or move the keyboard until it does.

Set the height by your elbows

Two findings from the Marcus study concern your elbows. Typing with an inner elbow angle above 121° was linked to a lower risk of neck and shoulder symptoms. Elbows lower than the J key, meaning a keyboard above elbow height, were linked to a higher risk. An angle above 121° means the elbow is opened wider than a right angle, so your forearms slope down toward the keys.

In practice, let your shoulders hang loosely, bend your elbows, and place the keyboard so that the home row sits at or slightly below elbow height. If your desk is too high for that and cannot be adjusted, raise your chair and put a footrest under your feet.

Where the keyboard sits

Three more findings concern the keyboard itself. A J key more than 12 cm (about 4.7 inches) from the front edge of the desk was linked to a lower risk of hand and arm symptoms. That distance leaves room for your forearms in front of the keyboard. Measure it once and push the keyboard back if needed.

A J key more than 3.5 cm (about 1.4 inches) above the desk surface, on the other hand, was linked to a higher risk of hand and arm symptoms. Check your keyboard with a ruler. If the home row sits higher than that, fold in the feet at the back or choose a flatter model.

Keys that need more than 48 g of force to register were also linked to a higher risk. If a keyboard’s specifications list an activation force, a low value is the better choice. The inch values in this article are our conversion.

Type with a light touch

Touch typing needs little force. Press each key just far enough to register, then let the finger return to its place on the home row instead of resting on the key. Where each finger belongs is explained in The home row: where every finger belongs.

Keeping your hands in place also pays off in speed. In a study of everyday typing by Feit, Weir, and Oulasvirta, little movement of the whole hand was one of the traits of fast typists. More on this in How to type faster: what the research says.

The mouse and your breaks

One finding from the Marcus study is easy to misread: the 5° threshold concerns the mouse, not the keyboard. Bending the wrist toward the thumb by more than 5° while using the mouse was linked to a higher risk of hand and arm symptoms. Keep the mouse close to the keyboard and at the same height, and move it with your hand in line with your forearm.

Time matters too. More hours of typing per week went along with more hand and arm symptoms. You cannot always type less, but you can spread the work over the day and change your position now and then. For learning, short sessions are enough anyway. We recommend 10 to 20 minutes a day, and How long does it take to learn touch typing? explains why short daily practice works well.

When to see a doctor

All of these findings are statistical links. They do not show that a certain angle causes pain, and following them does not guarantee that you will stay free of symptoms. If pain, tingling, or numbness in your hands, arms, neck, or shoulders keeps coming back or does not go away, see a doctor instead of adjusting your desk again and again.

With your desk set up, try the posture on a few keys: the first lesson in the trainer uses only F, J, and the space bar, so you can keep an eye on your wrists while you type.