What Causes Rigid Bones When Diagnosed With Parkinson S Disease?

Hi: My husband has Parkinson s. His problem is not shaking but rigidity in his bones. Mainly in his thigh area of his legs. He has an appointment with a pain management doctor next week. We are trying to see if anything can be done to ease the tightness in his thighs when he try s to walk more than 100 yards. He is forced to sit down for at least 5 minutes to be able to continue his walk. He has also fallen a few times. He doesn t want to go into a scooter. He was a marathon runner most of his life. What do you think?