I use these for CrossFit, and they work very well. My feet feel snug inside the shoes, and with zero drop they keep me close to the ground and stable throughout my workouts. There's room at the front for my toes to spread out as needed, yet the shoes don't slip around my feet when they get sweaty. I've only run short distances, and they feel fine, but I don't think they're the best choice for long distance running. I wear a 12 normally, and wear the same with these, though some of my smaller friends say they've had to use different sizes than normal.