AUTHORS: Caitlin D. Stover, Ryan Z. Amick, David E. Geddam, Kaelin C. Young, Jeremy A. Patterson, FACSM
ABSTRACT: The ability to reduce functional limitations in older adults is a significant public health concern. With increasing age, many functional abilities can decrease secondary to physiological changes, limiting the ability to perform activities of daily living. Improved balance and lower extremity strength have been shown to be associated with reduced functional limitations in older adults. Additionally, improved lower extremity strength has been shown to improve balance in older adults.
PURPOSE: The purpose of this study was to determine the association between lower extremity strength and balance as measured with a new balance assessment technique.
METHODS: 48 independent living older adults (21 male, 27 female; 59.7 (6.7) yrs) free of conditions known to affect balance, completed the SWAY balance assessment. The assessment utilizes a software application which accesses the accelerometer in a commonly available mobile consumer electronics device. For the balance assessment, the device is held against the chest at mid-sternum level. The assessment consists of 5 balance stances including feet together, tandem right foot front, tandem left foot front, single leg stance (SLS) right and SLS left. Each stance is assessed for 20 seconds. Upon completion of all balance stances, a balance score was generated. Lower extremity strength was then assessed by maximum voluntary contraction (MVC) with an isokinetic dynamometer for knee flexion (MVC-fl x) and extension (MVC-ext).
RESULTS: Mean MVC were 78.2 (26.3) Nm and 160.0 (61.8) Nm for MVC-flx and MVC-ext respectively. Mean SWAY score was 66.1 (16.6). A significant negative correlation was found between both the SWAY balance score and MVC-fl x (r= -0.289, p<0.05) and MVC-ext (r= -0.295, p<0.05). However, after controlling for age and sex, balance and strength associations were no longer significant (p>0.05). Age was the only observed significant independent variable within the regression model (r= -0.442, p<0.01).
CONCLUSION: The negative correlation found between SWAY and lower extremity strength may result from the SWAY Balance Mobile Application measuring balance differently than traditional methods. Additionally, the negative correlation between balance scores and age may indicate that age is the predominant factor in reduced balance observed in older adults irrespective of lower extremity strength.