Under a large perturbation or when ankle stability is limited, which postural strategy is typically engaged?

• A. Hip strategy is typically engaged first; stepping may be necessary for large perturbations.
• B. Ankle strategy is always used first.
• C. Stepping strategy is never used for perturbations.
• D. Visual strategy is used to plan steps.

Answer: (B)

The main idea is that postural responses follow a progression: start with ankle corrections, then recruit the hips, and finally step if necessary. The ankle strategy uses tiny to moderate ankle torques to shift the center of mass over the base of support with minimal movement, making it the most efficient and typical first response to balance disturbances. When the perturbation is large, or when ankle control is limited, the system escalates to hip strategies to use larger trunk and thigh motions, and if sway would still push the center of mass outside the base, a step is taken to widen that base. Visual planning plays a role in anticipating steps, but it isn’t the immediate corrective mechanism for sway. So, even in big perturbations or with limited ankle stability, the initial, default response is to engage the ankle strategy first, with other strategies recruited as needed.