yes Rumpled is right , depends on what they can do, just up and walking around the house is good, anything that gets them to moving
I think it can vary on what stage they are in and their overall health at the time. My MIL was given pt at home (which her husband ignored to her detriment) that was about 10 minutes a day. When my FIL was diagnosed he just did a short walk daily like 1 -2 minutes with a walker as he was so degraded as we could not get him to walk.
I know exercise is totally important, but it depends on the caregiver and the health of the person on what they can do.