For the OP: The fact that you're researching this for her shows how much you care, but sometimes the reward of testing your current abilities outweighs the risk (and it is likely small in your friend's case) of a change in her disability status from a review.

Considering her age, diagnosis of injury, and the fact she has been receiving benefits for many years, it likely won't be an issue.

There was a period when I was taking 1 class a week at the local Community College while I was in the application process. My attorney tried to vaguely discourage me, but my mental health was more important to me. Did it hurt my 1st application? I think it did. When I received my Fully Favorable decision it included the timeframe I had taken classes. Eventually I adapted to a more solitary existence and the pain incurred from going to class 1 night a week no longer made sense for me.

And while I hope your friend reaches her goal, you have to consider if her journey towards it might end up being just as important for her.