I read an article on tnation (ill be damned if i can find it now, but ive been looking) it said that size is accumalated by volume
it was something like this: reps x sets.
take your reps, multipy by sets and if the product is:
1-20: necessary growth only, sarcomere
20-35: sarcomere and sarcoplasm
35-50: mostly sarcoplasm
rule of thumb is, the more of one side the less you should have of the other. course there are exceptions. You want functional strenght? stay at about 85% intensity or above, 85% is ave 5rep max. Look into mark rippetoes starg]ting strength if you are a beginner. bill stars 5x5 if you are intermediate, or glenn pendlays advanced variation if you are advanced. they cut out the crap you dont want.
one more thing, for most ppl it is inevitable to gain at least some extra msss (fat, sarcoplasm what have you) Just cut it when you reach your goal. That's what im doing when i max out my sarcomere i am gonna cut down to 5% bf or less