Frontal plane hip rotation mainly reduces what type of COM displacement?

Frontal plane hip rotation mainly reduces what type of COM displacement?

• A. Side-to-side
• B. Upward
• C. Rotational only
• D. Downward

Answer: (A)

In this context, motions in a given plane often serve to limit the center of mass movement in that same plane. Frontal plane hip rotation—think of the hip guiding abduction/adduction and the pelvis’s tilt during stepping—primarily helps keep the body’s mass closer to the midline, reducing side-to-side (mediolateral) COM displacement during gait. Vertical changes (upward/downward) are driven mainly by movements in the sagittal plane, and rotational displacement around the vertical axis isn’t the main outcome of this hip motion. So the best answer is side-to-side.

In this context, motions in a given plane often serve to limit the center of mass movement in that same plane. Frontal plane hip rotation—think of the hip guiding abduction/adduction and the pelvis’s tilt during stepping—primarily helps keep the body’s mass closer to the midline, reducing side-to-side (mediolateral) COM displacement during gait. Vertical changes (upward/downward) are driven mainly by movements in the sagittal plane, and rotational displacement around the vertical axis isn’t the main outcome of this hip motion. So the best answer is side-to-side.