During which gait phase does the second vertical GRF peak occur?

During which gait phase does the second vertical GRF peak occur?

• A. Terminal stance
• B. Initial swing
• C. Mid-swing
• D. Terminal swing

Answer: (A)

The second vertical ground reaction force peak appears during late stance when the body is preparing to push off. In terminal stance the ankle plantarflexors drive propulsion and the weight shifts onto the forefoot, causing a rise in the vertical reaction as the limb transitions to toe-off. The other phases—initial swing, mid-swing, and terminal swing—are non-weight-bearing or light-weight-bearing for the reference leg, so they don’t produce that second peak.

The second vertical ground reaction force peak appears during late stance when the body is preparing to push off. In terminal stance the ankle plantarflexors drive propulsion and the weight shifts onto the forefoot, causing a rise in the vertical reaction as the limb transitions to toe-off. The other phases—initial swing, mid-swing, and terminal swing—are non-weight-bearing or light-weight-bearing for the reference leg, so they don’t produce that second peak.