The first vertical GRF peak occurs during which phase?

The first vertical GRF peak occurs during which phase?

• A. Terminal swing
• B. Loading response
• C. Mid-swing
• D. Pre-swing only

Answer: (B)

The first vertical ground reaction force peak happens when the stance limb begins to accept the body's weight right after heel contact. This loading response phase is when the knee and ankle flex to absorb shock and the body’s weight presses down on the ground, creating the initial peak in the vertical GRF. The second peak comes later during push-off in late stance, not at the start. So the first peak is during loading response.

The first vertical ground reaction force peak happens when the stance limb begins to accept the body's weight right after heel contact. This loading response phase is when the knee and ankle flex to absorb shock and the body’s weight presses down on the ground, creating the initial peak in the vertical GRF. The second peak comes later during push-off in late stance, not at the start. So the first peak is during loading response.