Which example best illustrates anticipatory postural adjustments?

• A. Pre-tensing of trunk muscles before lifting a heavy object
• B. Ankle strategy after platform tilt
• C. Automatic stepping after perturbation
• D. Reactive trunk stabilization after losing balance

Answer: (A)

Anticipatory postural adjustments are pre-planned muscle activations that stabilize the body before a movement that could disrupt balance. Pre-tensing the trunk muscles before lifting a heavy object is a classic example: the trunk muscles activate in advance to stiffen the spine and position the body to counter the upcoming load, helping keep the center of mass over the base of support as the lift begins. This pre-activation reflects feedforward control, relying on prediction and planning.

The other scenarios represent reactive responses to disturbance. Adjusting the ankle after platform tilt, taking a step after a perturbation, or stabilizing the trunk after losing balance all occur in response to a loss of stability, not before the movement starts. They are essential for recovery, but they aren’t anticipatory.