Postural variability

Scientific basis

Stabilometry records the displacements of the center of pressure on a force platform. From these, indicators of amplitude (area, velocity, range) and of temporal structure are derived, using linear and nonlinear measures.

Research on movement variability suggests that a healthy system shows an intermediate and structured level of variability: variability that is too low (rigidity) or too high (instability) can accompany a loss of adaptability. Its interpretation depends on the task, the duration and the person. In sitting, it includes shifts in support and changes of position.

Blue Portance / SBNFA™ reading

In the SBNFA™ reading, postural variability is an observable manifestation of postural adaptability, not a measure of it. The framework does not use it as a score: moving more is not a goal, and high variability can also reflect restlessness or a painful compensation.

Contribution to the analysis of sitting

Seating analysis describes the variation in support and the changes of position over time, and interprets them according to the task, the duration and the person's tolerance.

Not to be confused with

Micro-movements, the small-amplitude displacements themselves, whose distribution over time is described by variability; postural adaptability, a functional capacity of which variability is one manifestation among others; restlessness and instability, which are not desirable forms of variability.

Related terms

Micro-movements · Postural adaptability · Postural control · Continuous postural regulation

Sources and scope

• Stergiou and Decker (2011): human movement variability, nonlinear dynamics and pathology (Human Movement Science)
• Winter (1995): balance and posture control during standing and walking (Gait & Posture)