I bought these around 8 months ago.  When you first get them, it does feel like you are working your legs and butt out more as the air bubble makes you have to put extra effort out.  However, within a couple weeks, you adjust and they just seem like normal sneakers.  Therefore, I doubt they keep doing the same thing.  The sole has actually been falling apart on mine recently, although I don't wear them often, and when I walk now you can hear the air go out of the one bubble so its kind of impossible to wear because they are loud.