I know its important to keep the body guessing so that muscle gains don't come to a hault, but I was wondering how much I have to change things in order to keep the body guessing. Is changing the set and rep range enough? For example if I train chest one week doing 4X5 then 3X8 and finally 2X15 week 3 and start the cycle again week four is that enough? Or will the body adapt to this too? The only other thing I can think of doing is using dumbells instead of a barbell, but I rather not change exercises because I would like to continue using heavy compound movements.