Just look at Frank Mir, from the time Lesnar beat him him down to now hes put on like 30-40 lbs of muscle. lol, he put on 25lbs. and no most ufc guys dnt use roids. most pro mma fighters are in the gym 6 days a week. lifting, cardio, boxing, jiu-jitsu, ect, ect. as said they use alot of fast twitch muscles. More @Wikipedia
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