Originally Posted by M4rdyB

Alien, with your mum just make sure she uses it at relatively low speeds for 5-10 minutes at a time. People don't get the technique straight off so it'll take a bit of practice to get the thing going and more importantly keeping it going. It's a proven exercise tool that has helped an array of conditions if used correctly, so your mother should benefit from it. I myself have now much more toned arms and stronger wrist and finger joints from using the ball for an hour twice a week.