My back is thankful. Wonderfull product. I have a friend who has 15 pair of Z-Coils and she let me borrow a pair for a few days to see if they would work for me as I have had total knee replacement on both knees and wanted to make sure they wouldn't hurt my knees. My problem now is my lower back thus the purchase and I am thrilled to say my back is already at least 50% better after just a couple of days and no problem with knees at all.
I highly recommend these shoes and the Z-Coil customer service is terrific. Don't be afraid to give them a try your body will thank you.