Toning shoes are shoes that are designed to help the wearer ‘tone up’. They do this by being inherently unstable in their design, so muscle activity is increased to compensate for this instability. Most of the toning shoes use a rocker design to achieve this in an anterior-posterior direction. Some do try to increase the side to side rocking motion. There is a lot of controversy about these shoes, as most of the claims made by the manufacturers are not backed by research or clinical outcome studies. The most well-known of these shoes are the MBT shoes, Skechers and the Reebok Tone Ups.