It's not really that important to get wrapped up in what stage you're in, but the exercise class you're in should have a group of individuals who are at your level because if you can't be challenged to the peak of your abilities then you can't be making as much progress as possible.

For example, if you're going to a class and you're symptoms are mild to moderate, but you're in a class of people who are not able to stand and the instructor is tailoring their class to the average, you may not be getting the best workout possible.

In contrast, if you are someone who can't stand, and you're in a class where there are a lot of people who can stand, and the instructor is trying to do half the class tailored towards the people standing, and half the class tailored to people who are sitting, then you're not getting the highest benefit.

Having an occasional group class where you're participating as a community and everyone from every stage and walk of life is there can be really really motivating and amazing.

(For example, Power for Parkinson’s in Austin, Texas leads their group fitness classes with the mission to be inclusive of all abilities and their classes are incredibly popular with participants at all levels.)

However, I would also encourage you to make sure that you're working with a personal trainer or a Parkinson's physical therapist, individually, so a part of your overall exercise program includes someone taking you to the peak of your ability.