Neurophysiology · functional reading
Postural balance
Postural balance is the ability to keep or restore the projection of the center of mass within the base of support, both at rest and in motion. When sitting, it involves the trunk, the pelvis and the hips.
Scientific basis
Balance is one of the two goals of postural control, along with the orientation of body segments. It relies on the relationship between the center of mass and the base of support, and on the integration of visual, vestibular and somatosensory information. A distinction is made between static balance, maintained without moving the base of support, and dynamic balance, which incorporates movement.
When sitting, the base of support mainly comprises the sit bones (ischial tuberosities), the thighs and the feet. Seated balance then depends on how the trunk, pelvis and hips are organized, as well as on the available supports (feet, backrest, armrests).
Blue Portance / SBNFA™ reading
In the SBNFA™ reading, seated balance takes place within a space that is more or less extensive depending on the available degrees of freedom: this is what the cone of balance describes. The body regulates; the hips are the regulator. A static seat offers its own balance position: moving away from it requires holding or external support, without the seat “locking” the body. Balance is not immobility.
Contribution to the analysis of sitting
Seating analysis observes the distribution of support points, their variability and the way the person regains balance when leaning, turning or changing tasks. It does not measure balance in the clinical sense.
Not to be confused with
Cone of balance, an SBNFA™ concept that describes the functional space in which the body can move its center of mass and regain balance within it; postural control, the function of which balance is one goal; stability, a broader notion of resistance to perturbations; immobility: balance is maintained through continuous adjustments.
Related terms
Postural adaptability · Center of mass · Cone of balance · Postural control · Base of support · Continuous postural regulation
Sources and scope
- Horak (2006): postural orientation and equilibrium, the neural control of balance (Age and Ageing)
- Winter (1995): balance and posture control during standing and walking (Gait & Posture)
- Massion (1994): the postural control system (Current Opinion in Neurobiology)
An established scientific concept. This entry does not cover balance disorders or fall prevention, which call for medical evaluation.
