Further, not only physical properties are at work.  The mind must work with the body to reach a goal and is clearly focused on the task at hand.  Intent on the goal, no other thoughts should cloud the consciousness. 
Ego, emotion, and self-doubt cannot be left unchecked.  These three are self-defeating.  Obscuring judgement, these inner thoughts destroy any potential of performing at the optimum level.
True power is, utilizing the capabilities of the human body to their utmost perfection. Many exercises and routines can be followed to better these elements of power.  All can be helpful and may be necessary to rise above the norm. Throughout training it must be remembered that no exercise can replace that of the action itself.  Repetition leads to proficiency.  If the goal is to be a great basketball player, you must shoot baskets. To perfect a punch... PUNCH!  To perfect a kick... KICK! 
There is no substitute!