The experts say mouse elbow is caused by damage to the tissue of the elbow and arm because of repetitive movement.
Damage is also caused by clicking and moving the mouse too quickly and vigorously.
Mouse movements can also cause palm blisters. Joystick digit is the result too much finger use on controls.
Some spend so much time gaming they suffer black rings around their eyes and stiff muscles.
A third of the kids questioned even had shoulder blades in the wrong position because of over-playing.
And researchers think over-gaming could eventually cause heart damage.
The new study backs up UK campaigners' claims that computer games should have health warnings on them.