How many vertical GRF peaks occur during a typical stance phase?

How many vertical GRF peaks occur during a typical stance phase?

• A. Two
• B. One
• C. Three
• D. None

Answer: (A)

Vertical GRF during a typical stance shows two distinct peaks. The first peak arises right after heel contact as the limb rapidly absorbs impact and steers the body’s downward momentum into the ground. Then the force relaxes to a valley around mid-stance as the body passes over the foot. The second peak comes later in the stance as push-off occurs and the foot plantarflexes to propel the body forward, increasing the vertical reaction force again. So, two peaks reflect the loading phase and the propulsion phase of gait. A single peak would miss either the initial impact or the push-off, while three peaks aren’t characteristic of normal stance, and none would ignore these two key moments.

Vertical GRF during a typical stance shows two distinct peaks. The first peak arises right after heel contact as the limb rapidly absorbs impact and steers the body’s downward momentum into the ground. Then the force relaxes to a valley around mid-stance as the body passes over the foot. The second peak comes later in the stance as push-off occurs and the foot plantarflexes to propel the body forward, increasing the vertical reaction force again. So, two peaks reflect the loading phase and the propulsion phase of gait. A single peak would miss either the initial impact or the push-off, while three peaks aren’t characteristic of normal stance, and none would ignore these two key moments.