After the Doctor comments about the Master's weight and Colonel Trenchard replies he cannot get the exercise, the very scene has the Master is exercising on a rowing machine.
However, such a method would be seen as a substitute for genuine exercise, and only exercise for his upper body, not his legs. The term is not a strictly literal one, but a reference to the Master not being able to go outside.
However, such a method would be seen as a substitute for genuine exercise, and only exercise for his upper body, not his legs. The term is not a strictly literal one, but a reference to the Master not being able to go outside.
The door to The Master's "cell" is fully riveted, indicating that it's supposed to be solid steel, however given the way it handles and the sound it makes on closing, it's clearly a wooden door painted to look oxidised.