I've always thought that to gain muscle mass you had to do about 3 sets of 6-8 reps and reach muscle failure on every set. So I'd often lower the weight after each set to enable me to reach failure at the right time.. So my routine would consist of usually 4 exercises, 12 sets total, failure on every set. By failure I mean my muscles cant lift the weight anymore. I'm usually sore for many days after these routines.
Ok, so someone just told me you should never go to failure! It actually inhibits muscle growth! This cant be true can it? In my favorite movie, "Pumping Iron", they always lift till they are so tired they cant even move the weight. Isnt that the secret to success?