Which two strategies reduce upward displacement of the COM?

Which two strategies reduce upward displacement of the COM?

• A. Frontal hip rotation and horizontal pelvic rotation
• B. Stance phase knee flexion and frontal plane pelvic rotation
• C. Horizontal pelvic rotation and sagittal ankle rotation
• D. Toe extension and arm swing

Answer: (B)

Minimizing how high the body's center of mass rises during movement is achieved by actions that shorten or stabilize the body’s vertical path as you progress. Bending the knee during the stance phase acts as a shock-absorbing mechanism, allowing the leg to shorten and the body to sit a bit lower as weight transfers. This directly reduces the vertical swing of the center of mass. Along with that, rotating the pelvis in the frontal plane helps keep the upper body aligned over the stance leg during the weight transfer to the other leg. This lateral pelvis adjustment maintains balance and reduces the need for extra vertical lift as the body moves forward. Other options involve movements that either mostly affect ankle orientation, toe mechanics, or arm motion, which don’t have as direct an impact on lowering or stabilizing the vertical path of the center of mass.

Minimizing how high the body's center of mass rises during movement is achieved by actions that shorten or stabilize the body’s vertical path as you progress. Bending the knee during the stance phase acts as a shock-absorbing mechanism, allowing the leg to shorten and the body to sit a bit lower as weight transfers. This directly reduces the vertical swing of the center of mass.

Along with that, rotating the pelvis in the frontal plane helps keep the upper body aligned over the stance leg during the weight transfer to the other leg. This lateral pelvis adjustment maintains balance and reduces the need for extra vertical lift as the body moves forward.

Other options involve movements that either mostly affect ankle orientation, toe mechanics, or arm motion, which don’t have as direct an impact on lowering or stabilizing the vertical path of the center of mass.