Cup size seems to run a little big, I wear a 38DD in every other bra I own, but this one is just a tad too big.  Not so much I needed to return for a smaller size, just a little extra room. If you like your bra tight, go one size down.  The bra itself is wonderful when I run.  My "girls" are not squished together at all or flattened to my chest. The only downside is getting the bra on/off. You have to maneuver into the right position to get it over your head. Otherwise this would be 5 stars.