Blood Rheology

Abstract

Synonyms Equilibrium; Postural control; Postural stability Definition ▶ Balance is a complex and multidimensional phenomenon. It is defined as "the ability of an individual to successfully maintain the position of their body, or more specifically, the centre of gravity, within specific boundaries of space" [1]. Mancini and Horak [2] define the functional goals of the balance system as:-"maintenance of a specific postural alignment, such as sitting or standing;-Facilitation of voluntary movement, such as the movement transitions between postures; and-Reactions that recover equilibrium to external disturbances , such as a trip, slip or push." For healthy young people, balance is not stressed during routine activities, but may be challenged during higher level tasks including sports, or sensory challenged conditions or environments. For older people, effective balance is essential for safe, independent living, and maintaining an active lifestyle. Balance impairment is a strong, independent risk factor for falls among older people [3]. One in three people aged over 65 years fall each year. However, people with some health conditions such as stroke, Parkinson's disease, and lower limb arthritis have substantially higher risk of falling. Focus of This Entry While balance impairments can affect people of all ages, this entry will focus on assessment of balance performance , and training of balance impairment in older people (aged >65 years). This entry will also focus on balance in standing. The principles described can be applied at all ages [4] and all levels of balance abilities/ dysfunction, and to other positions (e.g., sitting), although the specific measures and training approaches need to be tailored to meet individual needs. Description Balance performance for older people can vary across a continuum, from very poor balance (e.g., unable to stand unsupported) through to high-level balance (e.g., performing in a seniors acrobatic group). While balance performance on all performance-based tests does decline with increasing age, the decline solely due to the effect of age alone is relatively small. Healthy older people have sufficient balance abilities to maintain stability while undertaking an active lifestyle. Rather, it is the impact of health problems affecting the various components of the balance system that are the major contributors to decline in balance performance of older people. Effective balance performance requires efficient sensory input (visual, vestibular, and somatosensory), central integration of this information, and effective and rapid motor responses (quick reaction time, generation of sufficient muscle force, sufficient joint flexibility, and good coordination) when balance is sensed as being challenged. When any component of this system is impaired through disease (e.g., cataracts, peripheral neuropathy, arthritis affecting lower limb joint flexibility and muscle strength), balance performance is reduced, and risk of falls increases. Balance is ▶ multidimensional, therefore is unable to be fully reflected in a single test score. Factor analysis of performance of various groups of older people, including those with moderate balance impairment and falls risk, has identified a number of sub-domains that should be considered in assessment and treatment. One commonly used sub-domain is ▶ static balance (measuring postural sway, or timing ability to maintain stance) in a range of increasingly challenging stance positions (feet apart, feet Frank C.