Core concept · SBNFA™

Cone of balance

In SBNFA™, the cone of balance refers to the functional space within which the body can move its center of mass, stop, remain stable and then move again, and respond to a perturbation without losing control of its posture.

Scientific basis

The concept extends the cone of economy described by Jean Dubousset: in standing, the body maintains its balance at minimal energy cost when its organization is efficient, within a limited zone of sway.

Balance control relies on a continuous loop: perception (proprioception, vision, vestibular system), integration by the nervous system, then action. To recover balance, the body uses ankle, hip or stepping strategies.

Blue Portance / SBNFA™ reading

The cone of balance is not a measurable anatomical volume: it is a representation that links Dubousset's model to the mechanisms of dynamic postural control. It adds to the cone of economy the capacity to move, to self-correct and to change support.

SBNFA™ transposes this framework to the seated position, where the pelvis and hips become the main actors of regulation. This transposition is a construction of the framework and not a direct validation of any device.

In the framework, this space is continuous: it is not divided into distinct positions and does not impose a zero point. A seat that makes macro and micro degrees of freedom available can offer a continuous balance space of up to ±45°, within which it is the body, through the hips, that regulates.

Contribution to the analysis of sitting

The question to ask of a seat is not "does it move?" but "what does it allow the pelvis and hips to mobilize, stabilize and adapt?". A seat can thus be analyzed according to the range and freedom of the adjustments it leaves possible.

Not to be confused with

Cone of economy, Dubousset's model describing standing balance; postural balance, the capacity to maintain or restore the center of mass over the base of support, which the cone of balance places within a functional space; base of support, the area bounded by the points of support; continuous postural regulation, the process that brings this space to life.

Sources and scope

An SBNFA™ / Blue Portance interpretive concept, built from Dubousset's cone of economy and the literature on postural control. These sources do not directly validate the concept.