They make you use your calfs more and force you in a more upright posture. I didn't get them for exercise though. More for long distance walks on boardwalks and city streets. I also hope I can correct how my feet angle outwards when I walk, and I strike the medial side of the foot with more force. When you walk in normal shoes afterwards, it feels like your foot sticks to the ground. That's when you notice your calfs are sore. I will post an update in several months when I get used to wearing them for long periods of time.