A review of research into work hours and postures while using a computer keyboard. The review finds that hours and posture are associated with adverse upper limb symptoms often enough to consider that an association is meaningful. Symptoms are not the same as injuries.
Evidence from:
F Gerr et al. J Occup. Rehab. (2006) Vol.16 p 265 – 277
“Keyboard use and musculoskeletal outcomes among computer users”
The authors conclude that exposure measurement is a key weakness of studies of proposed links between keyboard use and upper limb symptoms. As it stands there is a slight balance in favour of a conclusion that longer hours of use increase the rate of adverse hand/arm symptoms.
Further detail: