Betty,
That's great that you are exercising. I think it can make a big difference for people with Parkinson's ... and certainly can't hurt. There are some studies that indicate rigorous exercise may be neuro-protective.
I've been involved in a rigorous exercise program for about a year. It's made a difference in my physical abilities. My gait and posture are better plus I have more physical confidence overall.
The exercise program I'm involved with is a boxing-based fitness program. They work us up to a sweat for sure. We don't hit people - just heavy bags, speed bags, etc. We also jump rope, do jumping jacks, sit ups, push ups, leg lifts, etc. etc. etc. Each person's abilities are different. There are folks from their 20's to 80's.
I encourage you to push your limits. To quote a couple of exercise-related researchers, 'Too much is just enough'.
paula