Gyrotonic is a unique system of exercise that incorporates movement principles from yoga, dance, gymnastics, swimming and t'ai chi. Central to gyrotonic is the Gyrotonic Expansion System, or GXS, a specially designed machine with rotational discs and weighted pulleys that allow the exerciser to strengthen their muscles using flowing, circular movements. Ideal for rehabing hip, knee, shoulder and spine conditions. (must be aproved if under doctors care)