I have suffered from short-term wrist pains once in a while. For me there are only three causes:
- Hitting the piano too hard. Many years ago I accompanied an operatic society chorus singing 'With cat-like tread' from Gilbert & Sullivan's 'Pirates of Penzance', which has sudden loud chords. I was playing a Steinway in a large theatre, and I hit the chords harder than I would on smaller pianos, and had a wrist-ache for a month afterwards!
- Sitting at the piano at the wrong height. I always play so that my lower arm rests very slightly lower than the top of the keys. Others will like different heights. I am very particular about getting this right, else I certainly would suffer from a wrist ache after only a short practice session.
- Having stiff shoulders. I like to play with the whole arms - there is a balletic aspect to music making whatever instrument you play.