Which motor strategy involves rapid hip flexion and extension to correct mid-sized perturbations?

Which motor strategy involves rapid hip flexion and extension to correct mid-sized perturbations?

• A. Weight shift
• B. Stepping
• C. Suspension
• D. Hip

Answer: (D)

The hip strategy uses rapid hip flexion and extension to counteract sway by moving the upper body about the hips. This approach is ideal for mid-sized perturbations because it quickly shifts the trunk and center of mass back over the feet when small ankle adjustments aren’t enough, but the disturbance isn’t so large that you have to take a step. By flexing and then extending the hips, the body generates the necessary angular impulse at the pelvis and trunk to realign the center of mass with the base of support without moving the feet. In contrast, the ankle strategy handles tiny perturbations with ankle torques, stepping is used for large disturbances that require widening the base of support, and suspension isn’t typically recognized as a primary standing balance strategy.

The hip strategy uses rapid hip flexion and extension to counteract sway by moving the upper body about the hips. This approach is ideal for mid-sized perturbations because it quickly shifts the trunk and center of mass back over the feet when small ankle adjustments aren’t enough, but the disturbance isn’t so large that you have to take a step. By flexing and then extending the hips, the body generates the necessary angular impulse at the pelvis and trunk to realign the center of mass with the base of support without moving the feet. In contrast, the ankle strategy handles tiny perturbations with ankle torques, stepping is used for large disturbances that require widening the base of support, and suspension isn’t typically recognized as a primary standing balance strategy.