What is the external ankle moment during midstance?

What is the external ankle moment during midstance?

• A. Plantarflexion
• B. Dorsiflexion
• C. Inversion
• D. Hip flexion

Answer: (B)

During midstance the body’s weight is directly over the stance foot and the ground reaction force line lies in front of the ankle joint. This creates an external dorsiflexion moment about the ankle, meaning the external force tends to tilt the foot upward (toward dorsiflexion). The calf muscles then act to control this, producing an internal plantarflexion moment to stabilize the ankle and allow smooth forward progression. The other options involve motions not primarily produced as the external moment at the ankle during midstance (inversion is a subtalar/medio-lateral action, and hip flexion is a different joint entirely).

During midstance the body’s weight is directly over the stance foot and the ground reaction force line lies in front of the ankle joint. This creates an external dorsiflexion moment about the ankle, meaning the external force tends to tilt the foot upward (toward dorsiflexion). The calf muscles then act to control this, producing an internal plantarflexion moment to stabilize the ankle and allow smooth forward progression. The other options involve motions not primarily produced as the external moment at the ankle during midstance (inversion is a subtalar/medio-lateral action, and hip flexion is a different joint entirely).