List the three postural strategies and one EMG pattern that differentiates them.

• A. Ankle strategy: distal-to-proximal activation (calves first, then thighs/paraspinals); Hip strategy: proximal-to-distal activation (hip and trunk muscles first); Stepping strategy: rapid, large leg movements to establish a new base of support.
• B. Ankle strategy: proximal-to-distal activation; Hip: distal-to-proximal; Stepping: no muscle activation.
• C. Ankle: only in upper body; Hip: only in lower body; Stepping: only in arms.
• D. Ankle: synchronous activation; Hip: random; Stepping: delayed.

Answer: (B)

Postural control uses three distinct strategies to keep balance in response to a perturbation, and the pattern of muscle activation distinguishes them. In the ankle strategy, the body pivots around the ankle joints to correct sway, so the activation starts with distal muscles (calves) and then moves to more proximal muscles (thighs and paraspinals) in a distal-to-proximal sequence. This fine-tuning around the ankle works best on stable, solid ground with small perturbations.

If the perturbation is larger or the surface is less stable, the hip strategy takes over, and the body corrects by moving the upper body relative to the pelvis. Here the proximal muscles around the hips and trunk engage first, producing a proximal-to-distal sequence of activation as the movement is driven from the core outward to the limbs.

When the perturbation is too great for either ankle or hip corrections, a stepping response is used. This involves placing one foot to reestablish a stable base of support, accompanied by rapid, coordinated activation of the leg muscles to move the foot into position and stabilize the rest of the body through the new base.

The key EMG difference is the order and timing of muscle activation: ankle strategy shows distal-to-proximal activation, hip strategy shows proximal-to-distal activation, and stepping involves rapid, broad leg activation to execute the step and shift the base—not a simple no-activation pattern.