I was worried these would just slip off my shoes as I was dancing around to one of my Brazilian Butt Lift dvds in my carpeted living room, (btw, dancing around to those dvds on carpet while wearing sneakers is how I tore my meniscus resulting in surgery to fix it) but they totally worked and totally stayed on my shoes.  Zero knee pain.  I'm sure my butt will be nicely lifted in no time. 