On your feet all day. I have 2 bad knees, 1 is arthritis, the other has torn tendons and muscles. My knees always hurt after a day's work, as does my lower back. After I bought them I worked several long days and no problems! They are really very light on the feet. I'm blown away by the comfort and they look cute too! Normally you have to sacrifice one for the other. Not with these. Hopefully Adidas will keep these guys for a while.