Which GRF component is represented by the Z-axis?

Which GRF component is represented by the Z-axis?

• A. Anterior-posterior
• B. Vertical
• C. Medial-lateral
• D. Rotational

Answer: (B)

In gait analysis, the ground reaction force is broken into three orthogonal components: vertical, anterior-posterior (forward-backward), and medial-lateral (side-to-side). The Z-axis is defined as the vertical direction, pointing upward from the ground. Therefore, the component of the ground reaction force along the Z-axis is the vertical component, representing how much load is transmitted through the limb to the ground. The other directions correspond to forward-backward and side-to-side forces, while rotational effects would involve moments (torques), not a linear force component along an axis.

In gait analysis, the ground reaction force is broken into three orthogonal components: vertical, anterior-posterior (forward-backward), and medial-lateral (side-to-side). The Z-axis is defined as the vertical direction, pointing upward from the ground. Therefore, the component of the ground reaction force along the Z-axis is the vertical component, representing how much load is transmitted through the limb to the ground. The other directions correspond to forward-backward and side-to-side forces, while rotational effects would involve moments (torques), not a linear force component along an axis.