Longer steps and faster walking speed do what to anterior-posterior GRF magnitude?

Longer steps and faster walking speed do what to anterior-posterior GRF magnitude?

• A. Decrease it
• B. Increase it
• C. Eliminate it
• D. Reverse the vertical component

Answer: (B)

Longer steps and faster walking speed require larger changes in forward momentum from step to step, so the horizontal forces under the foot must increase. The anterior-posterior ground reaction force captures those forward- and backward-directed forces during stance. As speed or step length goes up, both the braking force when the foot hits the ground and the propulsive force during push-off become larger, boosting the overall magnitude of the anterior-posterior GRF. In other words, you need more horizontal push and more horizontal braking to move faster, so the AP GRF magnitude increases.

Longer steps and faster walking speed require larger changes in forward momentum from step to step, so the horizontal forces under the foot must increase. The anterior-posterior ground reaction force captures those forward- and backward-directed forces during stance. As speed or step length goes up, both the braking force when the foot hits the ground and the propulsive force during push-off become larger, boosting the overall magnitude of the anterior-posterior GRF. In other words, you need more horizontal push and more horizontal braking to move faster, so the AP GRF magnitude increases.