On land, the spatial magnitude of postural sway (i.e., the amount of sway) tends to be greater when participants look at the horizon than when they look at nearby targets. By contrast, on ships at sea, the spatial magnitude of postural sway in young adults has been greater when looking at nearby targets and less when looking at the horizon. Healthy aging is associated with changes in the movement patterns of the standing body sway, and these changes typically are interpreted in terms of age-related declines in the ability to control posture. To further elucidate the mechanisms associated with these changes we investigated control of posture in a setting that poses substantial postural challenges; standing on a ship at sea. In particular, we explored postural sway on a ship at sea when older adults looked at the horizon or at nearby targets. We evaluated the kinematics of the center of pressure in terms of spatial magnitude (i.e., the amount of sway) and multifractality (a measure of temporal dynamics). We found that looking at the horizon significantly affected the multifractality of standing body, but did not systematically influence the spatial magnitude of sway. We discuss the results in terms of age-related changes in the perception and control of dynamic body orientation.
Bibliographical noteFunding Information:
We extend our thanks to Nathan Blessing and ISE. In addition, we thank Samuel Taylor Coleridge, for poetic inspiration. Dr. Stergiou is supported by the Center for Research in Human Movement Variability of the University of Nebraska Omaha and the NIH (P20GM109090 and R15HD086828).
© 2016 Munafo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.