MINERVA MEDICA COPYRIGHT ® Contribution of muscle weakness to postural instability in the elderly A systematic review R. ORR Background and aim. 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. Design. A comprehensive search of electronic databas- es 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 ( ≥60 years) included healthy, community-dwelling cohorts, nursing home residents, frail, mobility- or func- tionally-limited adults but not persons with patho- physiological conditions or disease. Methods. Interventions of progressive resistance or power training to increase muscle strength/power were examined but studies that included balance or multi- modal 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 pow- er outcomes. Overall, 54% (27/50) of studies reported sig- nificantly improved strength and balance measures and 73% (16/22) showed improved power and balance fol- lowing resistance/power training intervention, where- as 84% and 86% of cross sectional studies observed sig- nificant associations between balance and strength/pow- er outcomes respectively. Conclusion. The findings suggest that there is some evi- dence for the contribution of muscle strength and mus- cle power to balance performance in older adults. There is, however, weak evidence for the cause and effect rela- tionship between muscle function and balance perfor- mance. Corresponding author: Dr. R. Orr, Exercise Health and Performance Faculty of Health Sciences The University of Sydney, East St, Lidcombe NSW, Australia. E-mail: rhonda.orr@sydney.edu.au Vol. 46 - No. 2 EUROPEAN JOURNAL OF PHYSICAL AND REHABILITATION MEDICINE 183 Exercise Health and Performance Faculty of Health Sciences The University of Sydney, Australia Clinical Rehabilitation Impact. Inconsistencies in the literature can be attributed to methodological limita- tions. KEY WORDS: Postural balance - Muscle weakness - Aged. T he aim of this review was to examine the contri- bution of muscle weakness to postural stability in healthy older adults and to determine the rela- tionship between muscle weakness and balance impairment Materials and methods Falls in older adults Falls and fall-related injuries are a major cause of morbidity and mortality in older adults, and there- fore, are a major public health concern. Approximately 33% of community-dwelling older adults fall at least once a year, with 10% experiencing multiple falls and over 30% suffering injuries requiring medical attention. Hospitalization from accidental falls accounted for 54% of all injury-related hospitalizations for adults over 65 years in 2001. 1 About 50% of hospitalized REVIEWS EUR J PHYS REHABIL MED 2010;46:183-220