My gym instructer said that to work on muscle size and strenght ur looking at heavy weights <8reps, <4 if ur really serious. But if ur looking for explosive strength, do 15-20 reps with shorts rests. this tones the muscles and gives good shape, because your doing the movments quicker your shaping and strengthening the muscles. Heavy weights will impaire your speed as the muscle grows bigger that it should naturally be.
If you look at the phsique of decathleats (my spelling sucks, sorry) and gymnasts, thats about the best all round body a human can get. They are strong and powerfull, without loosing speed. Thats what we (as martial artists) should be aiming for, in my opinion.
"Turn your face to the sun, and your shadows will fall behind you."
"While your looking to hit for points, we are breaking legs and taking you by the neck"