When is a change in support strategy typically triggered?

• A. Visual input dominates balance
• B. Stability limits exceeded or perceived to be exceeded
• C. Always on a level surface
• D. Only during walking

Answer: (B)

The trigger for changing how you support yourself comes from the stability limits being reached or felt to be reached. Your nervous system continually monitors where your center of mass sits within the base of support. If the projection of your center of mass approaches or crosses the edge of that base, or if you anticipate it will, the system shifts to a different strategy to regain stability—things like stepping to widen the base, grabbing a support, or widening your stance. This can happen in response to a perturbation or even in anticipation based on sensory information.

Visual input dominating balance isn’t the trigger itself; it affects how we weigh sensory information and time our responses, but the actual change in strategy is driven by crossing or perceiving that stability limit. And these balance adjustments aren’t limited to walking or to level surfaces—they occur in many tasks, including standing and reaching, whenever stability is at risk.