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Test–Retest Reliability of the Biodex Balance SD in Physically Active Old People

The aim of this study is to examine the reliability of measures of stability and dynamic balance obtained using the Biodex Balance System SD in physically active old people with low fear of falling.

Jose Alberto Parraca, Faculty of Sports Sciences, University of Extremadura; Narcis Gusi, Jose C. Adsuar, Pedro R. Olivares, Faculty of Sports Sciences, University of Extremadura, Caceres, Spain; Emilio Herrera, P. Alejandre, Assessorship for Health and Unit, Board of Extremadura, Merida, Spain

Introduction: Falls are the most common cause of accidental injuries in older people, and frequently result in disability and handicap, emotional distress and increased use of health and social services. Balance, or the postural stability function, can be described as the ability to maintain the center of gravity of the body over the base of support. It is an essential part of movement, skill, and independence, and it can be affected by drugs/medications, muscle weakness, traumas and central nervous system disorders. The aim of this study is to examine the reliability of measures of stability and dynamic balance obtained using the Biodex Balance System SD in physically active old people with low fear of falling.

Methodology: Forty-seven physically active old people (4 men and 33 women) took part voluntarily in this study. All of them signed a responsibility compromise approved by the Ethics Committee of the University of Extremadura, respecting the Helsinki declaration about the conduct of clinical investigations. The participants stood on the BBS supported with both legs and looking at the display constantly. All trials were done without shoes. In the postural stability test on the BBS the platform is static in the anterior posterior and medial lateral axes, and provides the measures: (OSi), an anterior posterior stability index (APSi), and a medial lateral stability index (MLSi). This test consisted of 3 trials, each 20 s in duration. In the fall risk test, the platform is unstable and provides one measure called an overall stability index, the fall risk index (FRi). This test was done with the standard configuration, 3 trials of 20 s, and a stability level 8.

Results: With respect to estimates of reliability, the intraclass correlation coefficient (ICC) for the fall risk test measures was found to be highly reliable (ICC = .91, r = .85; p < .001), with a coefficient of variation of the method of 18.7%, and the absolute threshold of minimum clinical relevance of an improvement is of 0.33 taking care of the accord limits. ICC for the static balance test measures was moderate (ICC = .68; r = .52; p < .001), and had a clinical threshold of improvement value of .35. On the other hand, discriminant analysis indicated that the subjective perception of fear of falling based on a questionnaire does not predict the objective measurement of the balance with the platform.

Conclusion: The Biodex Balance SD is reliable for measurement of dynamic balance, and the fall risk test in physically active old people may be useful for demonstrating the progress of older people with fear of falling. These types of results can be very important to the medical sciences, and health and quality of life investigations. Further studies are needed to provide a more complete evaluation of dynamic and static balance on the Biodex Balance SD.

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