Like many people, I was wearing a running a shoe to take Bootcamp or other fitness classes. I was lacking control and stability for movements like lunges and squats. I had a REALLY hard time finding a good cross trainer. I wear an 8 shoe and ordered and 8.5. I should have ordered size 9 like I would in a running shoe. But-I can wear the 8.5 and like them so much I am considering ordering another pair in the 9 as a back up shoe. My favorite part of this shoe is that it hugs the side of your foot a bit so there is not a lot of side to side movement of my foot slipping around.