Someone who remembers their physics should probably reply with actual numbers but I think lever forces are what is at play. A downward force approximate to the

Someone who remembers their physics should probably reply with actual numbers but I think lever forces are what is at play. A downward force approximate to the mass of the head (6-8kg) is applied, the neck is a lever, and the force at the other end reacts appropriately. Wikipedia says: if the distance a from the fulcrum to where the input force is applied (point A) is greater than the distance b from fulcrum to where the output force is applied (point B), then the lever amplifies the input force. So that says that you can get a higher output force than the input force, which in this case is the force applied due to gravity and mass (plus your walking motion).