Was doing side bends this morning when a trainer(who is a fat ass) told me they would make my obiiques bigger and consequently my waste bigger. I am also a certified trainer and so the argument started. First of all, I been doing them for years and my waste is not big.This is an old wives tale, if you ask me. No one's abdominal region ever became extremely hypertrophied from training. The distended guts you see in pro bodybuilders is from the extreme amounts of drugs, especially growth hormone. Obliques are very important for stabilizing the trunk during heavy lifting and preventing low back injuries during rotational type movements. Side bends also very heavily involve the quadratus lumborum, a small low back muscle which is important in low back stability.Well needless to say, he still was not convince. Who's, right.