ok guys i have a question that hopefully somone can explain for me, i understand that ur muscles can get used to a routine and every 4, 5 or 6 weeks its good to change ur program up to shock them, but my question is; if u r training for size and do 3-4 exersizes with reps of 6-8, then change ur program to reps of 8-10 or 12 at a lighter weight, will this shock ur muscle and will they still grow even though u r lifting a lighter weight. i was thinking about changing up my routine but as im training for mass i didnt want to change up reps or weight just in case.