If you are looking for Physical functioning outcome measures you have a difficult task. We tend to use the widely used functional measures of
10 metre walk
6 minute walk
Berg Balance Scale
Motor Assesment Scale
1 RM
Fitness testing

for the physical side of thing. Given that many over a long period of time deteriorate, to support physiotherapy intervention as positive in slowing deterioration in life and improving life styles we look to more holistic scales. In this point trying to tap into the positive benefits of exercise and what it has to offer this population in regard to their whole life.

SF 36
Quality of life Questionaire
Fatigue scales
ALD assessment etc.....

It really depends what you are trying to find out or support.

If you come across one that works well for you I would be interested in this