Proposal for a New Body Sway Evaluation Method

Abstract

SummaryThis study is aimed at examining body sway factors for 1,107 healthy people aged fifteen to 69 and to propose a practical body sway evaluation method. The center of foot pressure measurement was carried out twice for one minute with a 1 minute rest.Thirty parameters with high reliability selected from six domains (distance, distribution of amplitude, area, velocity, power spectrum, and body sway vector) were summarized objectively into four body sway factors (unit time sway, front-back sway, left-right sway, and high frequency band power). Factor scores were calculated by the estimate equation and the total scores of parameters with high factor loadings. Considering this result, a total score for each factor was classified into four percentile categoris based on percentile rank. Using this classification criteria, body sway scores for each individual were classified into any of the above four percentile categoris for each factor. It was confirmed that young adults mainly belong to percentile categoris A and B and the elderly mainly belong to percentile categoris C and D. It was found that a great effect on body sway occurred when an individual's conscious condition changed (contracting a cold or after exercise). In conclusion, the body sway of healthy people can be explained by these four sway factors. An evaluation of the body sway pattern using the four sway factors may enable us to concretely understand individuals' disorders and abnormal states in addition to changes in body sway that occur with aging.

The correlation comparison among body sway parameters from the gyroscope data sets

“…Whether it is in many terms such as area of sway, distance, distribution, time sway, front-back sway, left-right sway, and high frequency band power, etc. [4]. Furthermore, some parameters give the same characteristic.…”

“…The age range of subjects was restricted to 20-30 years because some studies indicate that the trunk or body sway increases by an age factor [4]. All subjects had to ensure that they were neither physically nor neurologically affected.…”

“…The characteristic is the mean value in pitch direction of body sway [4]. From our study the pitch direction is measured by X -axis of gyroscope sensor.…”

“…It is often measured subjects or patients by using the force plate to measure at the change or movement of the center of pressure or center of mass [3][4]. The popular studies is to measure the change of body sway direction in Anterior-Posterior (AP) direction or in Medilolateral (ML) direction [1,5].…”

The Effect of External Stimulus Produced by Vibration Stimulus Instrument on Body Sway

“…An ES is generally interpreted as follows: under 0.2 is a small difference and over 0.8 is a large one. Factor scores of each factor were used the total of standard scores of parameters with high factor loadings followed the method of Kitabayashi et al [9]. The level of statistical significance (α) was set p < 0.05.…”