I'm not a Parkinson patient nor a physician, but I do have reservations about the "no pain, no gain" philosphy, especially for middle aged and over people. While in my 30's I tried working out with weights on a weight machine. I read the recommendations in the weight training mags. But I developed a hernia. A coworker in his 20's also thinks he has injured himself. My reccommendation is that anyone who is on a streuous exercise program to proceed with great caution. Be careful to use proper form and not over strain. If you experience pain, stop! Go see your physician!