What is the concept of postural threat and its effect on balance in healthy individuals?

• A. Postural threat reduces arousal and increases sway.
• B. Perceived risk of falling increases arousal and stiffening; sway may decrease.
• C. Postural threat has no effect on sway or muscle activity.
• D. Postural threat only affects older adults.

Answer: (B)

When people feel a postural threat, the body responds by increasing arousal and shifting into a more protective, stiffened control mode. In healthy adults this shows up as greater co-contraction of leg and trunk muscles around the joints, especially at the ankles, which raises stiffness and reduces the amount of sway. The idea is to limit movement to prevent a large corrective step or fall, so even though arousal rises, the center of pressure excursions typically become smaller.

This response can also change how sensory information is used, with a greater emphasis on proprioceptive cues and a tendency to rely less on vision when stability is perceived as at risk. It's a safety strategy driven by perception of danger, not a general loss of balance. If the threat is strong or prolonged, the stiffening can become maladaptive, potentially increasing effort or reducing adaptability, but the core concept is that perceived risk elevates arousal and leads to a protective reduction in sway.