Which statement describes the effect of longer steps on the anterior-posterior ground reaction force?

Which statement describes the effect of longer steps on the anterior-posterior ground reaction force?

• A. Decreases it
• B. Increases it
• C. Reverses the vertical component
• D. Eliminates it

Answer: (B)

Longer steps require more forward propulsion to reach the next step. In late stance, the trailing leg pushes back against the ground, and the ground responds by pushing the body forward. That increased push translates into a larger forward (anterior) component of the ground reaction force. So the anterior-posterior GRF magnitude goes up with longer step length. It doesn’t reverse or disappear, since propulsion during push-off must still occur to advance the body; the key point is the greater forward component.

Longer steps require more forward propulsion to reach the next step. In late stance, the trailing leg pushes back against the ground, and the ground responds by pushing the body forward. That increased push translates into a larger forward (anterior) component of the ground reaction force. So the anterior-posterior GRF magnitude goes up with longer step length. It doesn’t reverse or disappear, since propulsion during push-off must still occur to advance the body; the key point is the greater forward component.