There is not a lot of padding on the back heel area.  The first time I used these shoes I only walked a few blocks and came home with blisters on both heels.  I bought them to workout, so I figured I would get used to them.  I just worked through the pain.  I normally rub wholes in my running shoes in that area of the shoes anyway, so I would avoid these for running or walking if you are prone to do the same.