
Originally Posted by
znak
Size is created by growth. Your body is absolutely brilliant in its ability to conserve energy. If you lift only low rep/high weigh, you body will adapt/grow to accomodate the loads you are giving until you hit a threshold. To get over this threshold/plateau, you have to trick it into growing again. Since it won't accomodate growth due to weight that you can handle, you need to change something- reps, intensity (work/time) or weight.
Once again, after changing your body being basically lazy and wanting to converve energy, will adapt as little as possible to deal with the new stimuli, but it will change/grow for a while and then stop.
Once again you have pateaued and you will have to change something... you could go back to "heavy", change your intensity, etc.
The short answer is size and strength require constantly changing stimuli to force your body to grow.
I have found the key to be intensity- not reps or weight.