Should we even take note that when the arms are extended to the high, standing or supine the navel moves up?
To a more demanding analysis, not only aesthetic or of appearance, the­re are two points of importance and ceaseless vital func­tion, both con­nect­ed to the Golden Ratio like this, into a square let's say with side = 2 meters (ideal measure for a square, though not evenly for all men; but we trust that the Vitruvian man could bear it well):
  • that of the solar plexus, at the base of the diaphragm, just above the na­vel: the balance of respiration and continuity once it has started the ear­th­ly life. This is 2 × Φ (1.236), i.e. the Golden Section point of the height of our man. To call to mind as the Φ of our square.
    It is the true virtual center of the body struc­ture, aro­und which the bo­dy develops after birth. Hence it vitalizes the bo­dy from the out­side and by the physical world, with a process that can partly con­trol, being the cen­ter of the energy as­so­ci­at­ed with ego.
    It is related with the third chakra that con­cerns the propulsive, ex­pan­sive, formative force, the ability to digest and trans­form into en­er­gy, ma­t­u­ra­tion, then the source of per­son­al po­wer, self-belief, and self­-worth.

    This center, called in fact the Navel Chakra as well as the Solar Plexus Chak­ra, is known as located between the navel and solar plexus,
    By the way, all this issue draws on the sketch of Leonardo, whose de­ta­iled proportions were not reliable as expected: e.g. if the head in the fig­ure would reach the upper side of the square as described, without in­ter­pos­ing a thick tuft of hair, the navel itself could move up­ward eno­ugh to satisfy a pattern of the body in the square, likely meet­ing at on­ce the Vit­ru­vi­an sta­te­ment and the true golden proportion.
    But we cannot change it; and this corroborates an al­ter­na­tive per­spec­ti­ve choice, provided it is founded and not contradictory.

  • that of the cardiac center, that vitalizes body and soul from within, as the door of the spiritual sphere and from which the first stage of life ori­g­i­­na­tes; once confirmed to be in relation to the [four] golden circles cen­tered on the solar plexus, this will reveal to be ( 2 × Φ ) 2 ( 1.528).
    It will be the Φ of our circumference.
Remembering that the square holds the soul of the Golden Proportion (page 16), it was instinctive – alike many other scholars in the world – checking among the two emblematic figures a sort of relation back, able to connect their realities. So that the 'center of the body' should not to be considered only a numeric or geometric factor, but a dynamic one.
What better than the Golden Ratio to suit this aim?
,How could this take place?