Long before working out became the thing to do, my grandmother had one of these! Thrown from a horse and injuring her spine, her husband, a doctor, had to tell her, "Do", as he called her, "you are still you, and I will always love you the same, but you will not be able to walk again".  Well, she just wasn't going to accept that, and long before anyone was ever expected to recover from this type of spinal injury, she just would not give up.  And walk she did.  Veeeerrrry Slowly. I have great memories of playing on it with all of the cousins when we were little.