Moving is essential to being "moveable". If you decide to sit or lie down for a large part of your day, you will get "tired' when you do decide that it is time to get up. It can be horribly difficult to move at times, so the time that one has when they are able to move is important insofar as ones muscle tone is concerned. There are no great answers to your dad's dilemma. I'll bet that his weakness comes with inactivity, and that can be very frustrating. It is not easy to force oneself to move, when getting up and walking is a dreaded thing to perform. And that is what is all part of this disease. I take Dexedrine, in the morning, which sometimes works well to keep moving. Dexedrine is not for everyone, as it has it's side effects that many cannot tolerate. Are you sure that your day's BP is taken regularly and is not bottoming out, as anti parkinson drugs tend to have this effect on BP, fine one minute, low the next, and thus orthostatic hypotension , that makes you sometimes feel really dizzy. I have passed out on more than a few occasions, and have been so weak that I just hit the nearest chair or just get down on the ground "just in case" I were to go down and out. Rising slowly from ones sitting or lying positions is recommended, and a few deep breaths before attempting to do anything physical are also a good idea. That' all I have to offer, sorry.