An exercise chair comprises a base and a seat. The seat has a back leg and
a front leg. The back leg is pivotally attached to the base and pivots
between a first position in which the back leg is at an acute angle
between the back leg and the base and a second position in which the
angle between the back leg and the base is substantially ninety degrees.
When the chair is in the second position, there is a gap between the
front leg and the base.