These shoes have made a tremendous impact on my workouts by providing increased stability and comfort. I have high arches and slim feet. I sized up one full size so I can place my pinky finger between my heel and shoe and have a little wiggle room for my toes. I found this to be the perfect fit. I did a full workout: 5 miles on a treadmill and 30 minutes of functional weight training on the first day and had no soreness or discomfort in my feet.