Sway may be an element of both stationary and moving dance figures. In moving figures, sway is commonly achieved as a natural result of body swing, but small amounts from other sources may be useful as an inflection. When inflection is used as a source of the sway, in order to achieve smooth body line, the inflection is often described in terms of stretching of one side of the rib cage and compression of the other side. This description helps to produce sway without the body line breaking awkwardly at the waist. Substantial abdominal strength may be needed to fully utilize this technique