Stover, Matthew. Revenge of the Sith
The Sith Lord lowered the limbless man tenderly to the cool ground above, and laid his hand across the cracked and blackened mess that once had been his brow, and he set his will upon him.
Live, Lord Vader. Live, my apprentice.
That could just be an attempt at force heal, or not.
As for Palpatine being all old and stuff. Look at Yoda. He's older and still kicked Dooku's and Palptaine's ass. Plus, isn't the Dark Side supposed to wither and waste your body?