We're both editors, and I'm a writer and computer programmer. She types faster and harder than I do, and I type for longer periods each day. The result has been steady damage to our wrists, concentrated in the tunnels that provide a passageway for the nerves, arteries and tendons that run from our arms to our hands. What happens is a progressive narrowing of the tunnels until they choke off the passageway. The constant pressure can make both hands immobile.
Some days are worse than others.
On the good days, carpal tunnel syndrome shows up as nothing more than a tingling numbness along the edge of the palm. On the bad days, the wrist swells up from pain and locks up. Even the slightest movement is impossible when that happens. And we now have wrist rests on some of the keyboards we type on. But the problem has not gone away.