Even if we can't reverse things, I think we still hope that we can slow down or even stop the progression.
Exercise is not going to hurt you. If we were talking about a drug, I'd say wait. But there are no side effects to working out.
If we were using ... an experimental drug, I would be the last person in the world to say go get it. But in general, the kind of exercise we're talking about is certainly not going to hurt.
Exercise almost completely protected against the loss of these neurons.