title: Contribution of muscle weakness to postural instability in the elderly. A systematic review.
abstract: OBJECTIVE
  The aim of this review was to examine the contribution of muscle weakness to postural stability in healthy older adults and to determine the relationship between muscle weakness and balance impairment.
  
  
  METHODS
  A comprehensive search of electronic databases was performed from earliest record to February 2010. All study designs that contained a measure of muscle strength or muscle power and balance performance in older adults were examined. Population. Participants (>or=60 years) included healthy, community-dwelling cohorts, nursing home residents, frail, mobility- or functionally-limited adults but not persons with pathophysiological conditions or disease.
  
  
  METHODS
  Interventions of progressive resistance or power training to increase muscle strength/power were examined but studies that included balance or multimodal training were excluded.
  
  
  RESULTS
  A total of 74 papers were eligible for review; 45 with strength measures only; 5 with power measures only and 24 papers containing both strength and power outcomes. Overall, 54% (27/50) of studies reported significantly improved strength and balance measures and 73% (16/22) showed improved power and balance following resistance/power training intervention, whereas 84% and 86% of cross sectional studies observed significant associations between balance and strength/power outcomes respectively.
  
  
  CONCLUSIONS
  The findings suggest that there is some evidence for the contribution of muscle strength and muscle power to balance performance in older adults. There is, however, weak evidence for the cause and effect relationship between muscle function and balance performance. Clinical Rehabilitation Impact. Inconsistencies in the literature can be attributed to methodological limitations.
authors.affiliation: Exercise Health and Performance, Faculty of Health Sciences, The University of Sydney, Australia. rhonda.orr@sydney.edu.au
authors.forename: R
authors.initials: R
authors.lastname: Orr
mesh_terms: D000058:Accidental Falls / Q000517:prevention & control*; D000368:Aged; D016206:Databases, Bibliographic; D005260:Female; D006801:Humans; D008297:Male; D018908:Muscle Weakness / Q000503:physiopathology* / Q000628:therapy*; D004856:Postural Balance; D055070:Resistance Training; D012307:Risk Factors