An index of the coordination between two limb segments or limbs during the performance of a cyclic movement. is based on calculating the phase angles for each limb segment or limb at a specific point in time and then subtracting one phase angie from the other. Relative phase ranges from 0 (or 360 degrees), which indicates an in-phase relationship between the limb segments or limbs, to 180 degrees, which indicates an antiphase (or out-of phase) relationship