Which senses are involved in balance?

Balance integrates vision, the vestibular system of the inner ear, and somatosensory information, especially proprioception. The nervous system weights these inputs according to the situation, relying more on the senses that are most reliable in a given context.

What is the difference between anticipatory and reactive postural control?

Anticipatory postural adjustments are pre-planned and occur before or during a voluntary movement to offset a predictable disturbance. Reactive postural responses are triggered by an unexpected perturbation and act to recover stability after balance is challenged.

Balance and Postural Control

Balance, or postural control, is the active process of keeping the body's centre of mass within its base of support, both when still and during movement. It integrates information from vision, the vestibular system, and proprioception and is a foundation for standing, walking, and almost every functional task physiotherapists work with.

Definition

Postural control (balance) is the regulation of the body's position in space for the dual purposes of orientation (maintaining an appropriate relationship between body segments and the environment) and equilibrium (keeping the centre of mass within the limits of the base of support).

Scope

This topic covers the components of postural control, the senses it integrates, the distinction between maintaining orientation and maintaining equilibrium, anticipatory and reactive postural adjustments, and why balance is treated as a multi-system skill. It is a reference-educational overview of how balance is controlled, not guidance on assessing or treating balance problems in an individual.

Core questions

How does the nervous system integrate vision, vestibular, and proprioceptive information to control balance?
How are anticipatory postural adjustments coordinated with voluntary movement?
What components of postural control are affected by ageing or neurological injury?

Key concepts

Centre of mass and base of support
Postural orientation versus equilibrium
Sensory integration (visual, vestibular, somatosensory)
Anticipatory postural adjustments
Reactive (compensatory) postural responses
Ankle, hip, and stepping strategies
Sensory reweighting

Mechanisms

Postural control is best understood as a multi-system process rather than a single reflex. The nervous system integrates and reweights information from vision, the vestibular system, and somatosensory (especially proprioceptive) inputs to estimate the body's position and motion, and uses this estimate to generate muscle activity that keeps the centre of mass over the base of support (Horak 2006). Posture and movement are tightly coupled: before and during a voluntary movement, anticipatory postural adjustments pre-stabilise the body against the predictable disturbance the movement will cause, while reactive responses correct unexpected perturbations (Massion 1992). Because the centre of mass moves outside the base of support during walking, dynamic balance during locomotion requires continuous control through foot placement and trunk regulation (Winter 1995). Rehabilitation frames balance as a trainable, multi-component skill (Shumway-Cook 2017).

Clinical relevance

Postural control underlies stability in standing, transfers, and walking, so understanding its components helps physiotherapists describe balance problems in terms of which systems or strategies are involved. This topic explains how balance is controlled as a basis for interpreting the evidence; it does not prescribe balance assessments or training for any individual, nor does it address fall-risk management at the personal level.

Evidence & guidelines

The topic rests on sensorimotor neurophysiology and biomechanics. Influential syntheses include Horak's account of orientation and equilibrium (2006), Massion's review of posture-movement coupling (1992), and Winter's biomechanical analyses of standing and walking balance (1995), with rehabilitation framing in Shumway-Cook & Woollacott (2017).

History

Twentieth-century physiology first studied balance through postural reflexes, but later work reframed it as an integrative, multi-sensory control process. Jean Massion's analyses of how posture and movement are coordinated, and Fay Horak's systems framework for postural control, helped move the field from a reflex view toward a model in which balance is an actively organised, adaptable skill.

Debates

Is balance one ability or several?: Postural control draws on multiple systems and strategies, and evidence that these components can be selectively impaired supports treating balance as a set of distinct but interacting capacities rather than a single global ability.

Key figures

Fay Horak
Jean Massion
David Winter
Marjorie Woollacott

Seminal works

horak-2006
massion-1992
winter-1995

Frequently asked questions

Which senses are involved in balance?: Balance integrates vision, the vestibular system of the inner ear, and somatosensory information, especially proprioception. The nervous system weights these inputs according to the situation, relying more on the senses that are most reliable in a given context.
What is the difference between anticipatory and reactive postural control?: Anticipatory postural adjustments are pre-planned and occur before or during a voluntary movement to offset a predictable disturbance. Reactive postural responses are triggered by an unexpected perturbation and act to recover stability after balance is challenged.