This question asks about the ergonomics of a particular keyboard for long programming hours, what I would like to know is about the ergonomics of using a keyboard in general. What are the most significant risks associated with it and how can they best be mitigated? Do the "ergonomic" keyboard designs make a difference and if so which design is most effective? If not do other factors such as wrist-rests, regular exercise or having a suitable height of chair or desk make a difference?
Do you have any direct experience of problems deriving from keyboard use and if so how did you resolve them?
Is there any good science on this and if so what does it indicate?
Edited to add: Wikipedia suggests that there are no proven advantages to "ergonomic" keyboards, but their citation seems pretty old- is that still the current state of play?