Reactive postural control is maintained by which mechanism?

• A. Automatic motor responses to CoM change
• B. Conscious voluntary adjustments
• C. Visual tracking of the environment
• D. Random, uncoordinated muscle activation

Answer: (A)

Reactive postural control relies on automatic, rapid motor responses triggered by shifts in the body's center of mass. When a perturbation displaces the CoM, the nervous system quickly activates coordinated muscle patterns to restore upright balance without conscious thought. These reflex-like reactions are fast and rely on spinal and brainstem circuits to deploy ankle, hip, or stepping strategies as needed. While conscious adjustments and visual information can aid balance, the core mechanism of reactive control is the automatic response to the perturbation itself, not deliberate, voluntary actions or random, uncoordinated muscle activity.