Explore how motor skills, sensory input, and cognitive processes interact to maintain balance and postural control. Learn why stability is vital in daily life and how it’s affected by environment, dual tasks, and neurological conditions.
When standing and walking, one of the greatest challenges is to shift and move the relatively high centre of gravity over the relatively small base of support (feet) in a controlled manner.
Limitations in our ability to balance have far-reaching consequences. Balance control correlates with independence, quality of life and self-efficacy [14,20].
Almost all neurological conditions have an impact on balance. That is why the training and improvement of balance are central goals in motor neurorehabilitation.
Literature in the field usually uses the term "postural control" (PC). However, the terms "equilibrium" and "balance" are often used synonymously (and have been in this article as well). Balance is defined as the "ability of a person not to fall" [12]. Postural control goes far beyond this, meaning to carry out "an action to maintain, attain or regain balance in any posture or activity" [12]. According to Horak and Macpherson, two basic factors are key: postural stability (active stabilisation of the body’s centre of gravity over the base of support by coordinating sensorimotor strategies) and postural orientation (often also referred to as postural alignment, i.e. actively maintaining the appropriate positioning of body parts in relation to the rest of the body and to the environment) [3,8].
In order to be able to systematically map and analyse the complexity of postural control, many well-known researchers propose using a framework [4, 9, 15, 17, 18]. One of the most widely used framework models in the field is Shumway-Cook / Woollacott [5]. This will be referred to below.
- Active upright standing against gravity
- Appropriate positioning of body parts in relation to the rest of the body and the environment
- Active control of the body’s centre of gravity over the base of support by coordinating sensorimotor strategies (postural synergies) with internal and external influences
According to Shumway-Cook & Woollacott, postural control is the result of the interaction of the individual (person who is moving), the task (activity) being performed and the environment in which the activity takes place [17]. We will use the term "interaction model" below.
Three basic aspects are required from the individual: motor skills (action), sensory function (perception) and cognition. We will focus mainly on three types of postural synergies: the ankle and hip joint strategies and protective responses (walking or supporting). They are necessary both for anticipatory and reactive postural control [17]. The anticipatory adjustments are also referred to as "anticipatory postural adjustments" (APAs) [11]. They allow for postural adjustments before performing a focal movement, e.g. lifting an arm while standing (internal influence). The limb movement sets the centre of gravity in motion. This "disturbance" is calculated in advance and the appropriate muscles are activated to ensure postural control.
A functioning ankle strategy is crucial for this to work. It defines the space in which the centre of gravity can be shifted while maintaining control with an upright posture (alignment). This potential movement space is called the "cone of stability" [16]. It defines the limits of stability when standing. All activities when standing (arm movements, weight transfers, etc.) take place in this movement space. The bigger it is, the better the balance.
The response to external, unpredictable influences is also important. In these situations, for example, the implementation of a fast protective step is very important (reactive postural control) [10].
- Integration of sensory input from different information sources: Vision, balance organs and somatosensory (proprioception and surface sensitivity).
- Sensory weighting (depending on the situation, the CNS weights the sensory input differently. In a dark room, for example, the somatosensory input has to be given greater weighting than the visual input)
- Body schema (internal representation of the body)
- Dual or multiple task capability: In everyday life, we are required to adapt to a constantly changing environment [15]. To do so, we need to divide our attention. Part of our attention "stays" with the PC, another part is focused on the environment.
- Self-efficacy: Feeling capable of exercising control over actions makes us feel self-effective. The degree of self-efficacy we feel determines how we behave and how we assess situations and handle them [7].
Since movements always take place in an environment, this aspect also significantly influences postural control. From a therapeutic point of view, the challenge is to assess which environmental factors are relevant and therefore to be given special consideration. For instance, the type of floor has a big impact on postural control. Different requirements arise when, for example, the floor is unstable or stable, flat or sloping, slippery or solid, etc. Distractions (other people), the use of aids (stick, walking frame) or lighting conditions can also have an impact.
The task can be structured in terms of postural control according to the following criteria: steady state (static), dynamic-anticipatory and dynamic-reactive [17]. These are known as "balance mechanisms". They can be used to indicate the very basic "nature" of the (balance) task. Other relevant aspects of the task include use of the upper limbs, change of position (turning while standing, standing up/sitting down), different types of walking including tasks that often lead to balance difficulties or even falls, such as the transition from sitting to standing, turning, walking [1,2,13].
- Batchelor (2012) Falls after stroke. International Journal of Stroke.
- Cheng F-Y. (2014) Factors Influencing Turning and Its Relationship with Falls in Individuals with Parkinson’s Disease. PLoS ONE 9(4): e93572
- Horak FB. (2006) Postural orientation and equilibrium: what do we need to know about neural control of balance to prevent falls? Age and Ageing 35 (Supplement 2)
- Horak FB. (2009) The Balance Evaluation Systems Test (BESTest) to differentiate balance deficits. Phys Ther.89: 484-498
- Huber M. (2014) Posturale Kontrolle. pt Zeitschrift für Physiotherapeuten 66(5): 12-23
- Huber M. (2016) Posturale Kontrolle – Grundlagen. neuroreha 8: 158162
- Huber M. (2017) Yes, I can. Selbstwirksamkeit und posturale Kontrolle. physiopraxis 10
- Macpherson (2013) Posture. In: Kandel E. Principles of Neural Science. 5th edition McGraw-Hill
- Mancini (2010) The relevance of clinical balance assessment tools to differentiate balance deficits. Eur J Phys Rehabil Med. 2010 June; 46(2): 239-248
- Mansfield A. (2007) A perturbation-based balance training program for older adults: study protocol for a randomised controlled trial. BMC Geriatr. 7: 12
- Massion J. (1992) Movement, posture and equilibrium: interaction and coordination. Prog Neurobiol 38: 35-56
- Pollock A et al. (2000) What is balance? Clinical Rehabilitation 14: 402-406
- Robinovitch SN. (2013) Video capture of the circumstances of falls in elderly people residing in long term care: an observational study. Lancet 381(9860): 47-54.
- Schmid (2012) Balance and Balance Self-Efficacy Are Associated With Activity and Participation After Stroke: A Cross-Sectional Study in People With Chronic Stroke. Arch Phys Med Rehabil. 93(6):1101-7
- Schoneburg B. (2013) Framework for understanding balance dysfunction in Parkinson’s disease. Mov Disord Early view
- Schwab (2010) Adult Spinal Deformity – Postoperative Standing Imbalance. SPINE Volume 35, Number 25, pp 2224-2231
- Shumway-Cook A, Woolacott M. (2016) Motor Control. 5th edition. Lippincott Williams & Wilkins
- Sibley (2015) Using the Systems Framework for Postural Control to Analyze the Components of Balance Evaluated in Standardized Balance Measures: A Scoping Review. Archives of Physical Medicine and Rehabilitation 96: 122-32
- www.webb.org.au
- Weerdesteyn (2008) Falls in individuals with stroke. JRRD 45(8): 1195
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