Final answer:
The righting response to swaying too far posteriorly involves engaging back muscles and adjusting foot placement to realign the body's center of gravity with the base of support, which may also be aided by widening the stance.
Step-by-step explanation:
The proper righting response when the body sways too far posteriorly involves the repositioning of the body to maintain balance and equilibrium. To understand this, one must consider body mechanics, particularly how the center of gravity (cg) and the base of support interact. When an individual has good posture, the upper body's cg is directly over the pivot in the hips, which aligns vertically with the base of support provided by the feet. This positioning minimizes the need for muscle exertion to maintain an upright stance.
When there is a posterior displacement of the body, as one might experience with poor posture, the back muscles, which have a small effective perpendicular lever arm (rb), need to exert a significantly large force (F₁) to counteract the clockwise torque produced around the pivot by the upper body's weight. To correct from swaying too far backward, the individual would need to engage these muscles and potentially adjust foot positioning to bring the body's cg back over the base of support in the feet. In some cases, widening the stance by placing the feet farther apart can also help increase stability.