Final answer:
The heaviest level of force contact in the gait cycle occurs during the heel strike sequence when the foot makes initial ground contact.
Step-by-step explanation:
The heaviest level of force contact occurs during the heel strike phase of the gait cycle. During heel strike, the foot makes initial contact with the ground, which results in a peak in force as the body's weight begins to shift onto the leading leg.
This moment of impact is typically the most force-intensive part of the gait cycle, as it involves the body rapidly decelerating.