During loading response, vertical GRF is greater than body weight because it helps decelerate what?

During loading response, vertical GRF is greater than body weight because it helps decelerate what?

• A. Forward movement of the arm
• B. Hip internal rotation
• C. Downward movement of the body/COM
• D. Toe extension

Answer: (C)

The main idea is how the ground reaction force controls vertical motion of the body during loading response. At heel contact, the body's center of mass is moving downward toward the ground. The vertical ground reaction force rises above body weight, so it acts upward with more magnitude than gravity pulls downward. This creates a braking effect that decelerates the downward movement of the COM and absorbs shock, protecting the joints and preparing the limb for the next phase of stance. The other options don’t describe this vertical deceleration: decelerating forward arm movement, hip internal rotation, or toe extension aren’t the primary role of the vertical force during this moment.

The main idea is how the ground reaction force controls vertical motion of the body during loading response. At heel contact, the body's center of mass is moving downward toward the ground. The vertical ground reaction force rises above body weight, so it acts upward with more magnitude than gravity pulls downward. This creates a braking effect that decelerates the downward movement of the COM and absorbs shock, protecting the joints and preparing the limb for the next phase of stance. The other options don’t describe this vertical deceleration: decelerating forward arm movement, hip internal rotation, or toe extension aren’t the primary role of the vertical force during this moment.