intelligent man with mustache and glasses
One valid theory of bodybuilding exercise? A valid theory could be construed as a fact. If there is only one valid way to train you better not have examples of those who train differently from what you say who are successful.
I like Mike Mentzer. I still have just about every magazine article he wrote. He was someone who I copied his routines from for many years. I do have to admit he is a flawed individual as we all are in his sometimes insane rantings. Double blind studies considering if multiple sets are better than one set have been done but so many factors are beyond control such as motivation, experience, survey size and genetic athletic potential.
Many volume trainers do train to failure. Just that one to four sets are getting progressively harder as fatigue sets in and the last 5th set is failure. Getting stronger means different things. Is getting stronger a one rep value? Is getting stronger using an X amount of weight for 5 sets of 12 reps under a certain time frame also getting stronger? Both can be a goal but which is best for building muscle?
The fact remains and it's not a theory is that the majority of successful bodybuilders have used volume. Another fact is that all successful bodybuilders used by Arthur Jones to promote his machines and training principles were successful champions prior to his machines. One glaring example is Sergio Oliva who visited for a very short time to train on Nautilus who is used as a Nautilus success story. He used conventional equipment mainly prior to his visit and after his visit with plenty of volume.