Newton's Laws and Fitness

[sukha40]

I was wondering if anybody can help me out on this one.. I am doing a small project that requires me to:

Write how newtons laws relate to exercise, and give an example for each law.

[rcgldr]

One problem with this is that muscles use up engery to apply a force, even in the case that no movement is invovled (isometric exercises for example). Relating engery consumed to work done is tough when there are are cases where no work is done but lots of energy is consumed.

Of course there's the Newtonian law that for every force, there's an equal and opposite force (which can produce accelerations). This does apply to most forms of exercise.