Among older adults, hip fractures and injury-related hospitalization due to falls is a major concern. Upright postural stability depends on vision, vestibular, and proprioception sensory inputs. Proprioception, which integrates muscle spindles, joint and skin afferent fiber inputs, has been shown to decline across lifespans, in particular global versus distal-to-proximal, as indicated by results from a combination of self-report (Activities-specific Balance Confidence Scale), Joint Position Sense (JSP), Kinesthesia, and dynamic balance (Mini BESTest) from our lab. Significant differences in postural sway between age groups were not found in our static balance (force plate) measures (RMS displacement or RMS velocity). Using nonlinear time series measures of Applied Entropy (AppEn) and Hurst Rescaled Range (R/S), the purpose of this study is to determine the effectiveness of these measures in assessing postural stability and fall risk across the lifespan. Our current results suggest that, at least in the mediolateral direction, Applied Entropy is a more sensitive measure than Rescaled Range for postural sway.
