Postural control may have different goals under diferent circumstances, such as longitudinal alignment of the whole body to maintain a steady,
erect stance; remodeling of stance in preparation for a voluntary movement;
shaping of the body for display purposes, as in dance;
maintenance of balance, as on the gymnast's beam, or conservation of energy in a demanding task.
Different animals may use quite different postural strategies to achieve a steady stance in the face of gravity. Thus, as a result of sizedependent mechanics(allometry), the elephant mechanically locks its legs in line with the gravity vector to minimize the muscle forces supporting its heavy body. In contrast, small quad rupeds tense the muscles around flexed limb joints, thus permitting rapid responses to danger. (Tensing the muscles around flexed joints enhances. muscle stiffness, Since stiff muscle pairs mechanically resist change virtually instantaneously and hence well ahead of any active reflex response, opposition to unexpected perturbations is optimal.)