I was very surprised at how nice it fit! It wasn't too tight or loose for the girls or my sides. Im 36b and got a Large which was a perfect fit. Tried it on while i cleaned the house and almost forgot to take it off lol. However, I think i will have to test it out for HIIT to see how it holds up. Only reason i gave it 4 stars was because one of my bras had stitching issues on the inside back of the bra. Too many loose threads, but overall love the bra.