Dynamic analysis of high order activities of normal human postural sways

The methods of autoregressive and component-wave analysis were applied to quantitatively assess standing postural sways in humans. In 45 normal persons with the eyes open or closed, sway was divided into the two directions of anteroposterior and lateral movement. The optimum order of autoregressive processes for describing the sway was usually in the eighth to ninth order in each direction with either eye condition. In lateral sway the total power was larger with the eyes closed than with them open. A vector of the swaying was then calculated from the total power of the movement in both directions. The average was 48.2 +/- 15.9 degrees with the eyes open and 40.4 +/- 15.1 degrees with the eyes closed. These were significantly different (p less than 0.05). Most of the component waves were generally in the bands of 0 Hz, 0.5-2.5 Hz, 3.5-5.5 Hz, 7.5-8.5 Hz and 10.0 Hz in the two directions of sway and with either eye condition.