Abstract
In a previous report, we proposed a method for the frequency analysis of sway of the center of gravity in a standing posture. The method evaluated power-law distribution of the peak-area values in the spectrum from the frequency range 0.01Hz to 5Hz in. In this study, we improved this technique as a method to estimate a high frequency band (1-5Hz) and a low frequency band (0.01-1Hz) separately. Using our improved method, the body sway of 8 healthy adults and 10 healthy elderly people was examined. The elderly subjects showed the following results in comparison with the younger adults. 1) The first was a disorder of the power-law distribution in the low frequency band. This disorder suggests a failure of the interaction between the visual and vestibular systems on the maintenance of the standing posture. 2) The second results was an increase in value of the scaling exponent of power approximation indicating flattening of the power-law distribution curve. The flattening indicates an increase of random tendency of the sway. 3) The third was an increase of the peak-area values in the high frequency band. This finding indicates a failure of fine control of muscle activity by the proprioceptive system.
