Tamotsu Kitabayashi

Body‐sway characteristics during a static upright posture in the elderly

Aim:  This study aimed to determine the reliability and sex and age‐level differences of body‐sway parameters, based on center of pressure (COP) measurements, during a static upright posture in the elderly and to clarify their body‐sway characteristics in comparison with those of young adults.

CONCURRENT VALIDITY OF TESTS TO MEASURE THE COORDINATED EXERTION OF FORCE BY COMPUTERIZED TARGET PURSUIT

The purpose of this study was to examine concurrent validity of a new test for coordinated exertion of force. Coordinated exertion of force was measured using computerized target pursuit from the following viewpoints: the relations between the new test, a pursuit-rotor test, and a pegboard test. College students (24 men and 24 women) were required to change their grip exertion to match changing demand values (displayed in either a bar chart or a wave form) appearing on the display of a personal computer. The sum of the differences between the demanded values and grip-exertion values for 25 sec. was a parameter to evaluate the new test. The reliabilities of the new test, the pursuit-rotor, and the pegboard test were acceptable (ICC = .70 to .99). Scores on the new test showed low correlations with the pursuit-rotor and the pegboard test. The relation between the two different displays in the new test was significant but low (r = .49, p<.05). It was inferred that the new test measures a somewhat different ability than that measured by the pursuit-rotor and pegboard test and that the abilities tested by the types of displayed demand values are somewhat different.

Age-Stage Differences in Body Sway during a Static Upright Posture Based on Sway Factors and Relative Accumulation of Power Frequency

This study was done to examine age-stage (preschool children, young adults, and elderly people) differences in the center-of-pressure sway using body-sway factors (unit-time sway, front-back sway, left-right sway, and high frequency-band power), power-spectrum distribution, and relative accumulation of power frequency (25%, 50%, and 75% RAPF) of the center-of-pressure spectrum. The center-of-pressure movement for 1 min. was measured twice using Animas stabilometer. Data-sampling frequency was set at 20 Hz. Significant age-stage differences were found for 3 factors except for left-right sway, which was larger for preschool children and elderly than for young adults. The power spectrum of body sway in any age-stage was noted mainly in low frequency bands. A marked age-stage difference was found at 75% RAPF. Body-sway characteristics in each age-stage differ, and differences of postural-sway frequency are marked in the low frequency bands.

Gait characteristics when walking with rounded soft sole shoes

This study aimed to examine the effect of shoes with a rounded soft sole (Stretch Walker: SW) on gait. Fifteen healthy male (mean age: 23.2) walked under three conditions (SW, Flat-bottomed Shoe: FS, Barefoot: BF). Including walking speed, stance time, step length were selected as temporal-spatial parameters. The angle of hip, knee, and ankle joints during particular phases were selected as kinematic parameters. Walking speed, stance time, step length and flexion angle of the ankle joint at initial contact were greater when wearing either shoe than walking BF; cadence was faster walking BF than wearing either shoe; double support time increased (FS>SW>BF); step width was greater (FS>SW>BF); walking angle was greater wearing the SW than wearing the FS and walking BF; and range of motion and maximum flexion angle of the hip and knee joints were greater wearing the FS than walking BF. In conclusion, wearing the SW with a heel-to-toe rocker and soft sole changes the double support time, step width, and walking angle and increases step length and walking speed compared to walking BF. The difference of the range of motion in hip and knee joints was larger between walking BF and wearing the FS than between walking BF and wearing the SW.

COMPARISON OF POWER SPECTRUM CHARACTERISTICS OF BODY SWAY DURING A STATIC UPRIGHT STANDING POSTURE IN HEALTHY ELDERLY PEOPLE AND YOUNG ADULTS

This study was designed to compare peak frequency, mean power frequency, and power spectrum of each frequency band of body-sway time series and velocity time series power spectra between 30 healthy elderly people and 30 young adults and to clarify their frequency characteristics. Peak frequency and mean power frequency differed between groups, being higher for elderly persons, and the difference was marked in the front-back direction. When comparing power spectra of three domains (A: 0.02–0.2 Hz, B: 0.2–2.0 Hz, and C: 2.0–10.0 Hz) of an international standard, a significant age-group difference was found only in the front-back direction. Young adults were higher in the low frequency band (A domain) in sway time series, and the elderly group was higher in the high frequency band (C domain) in body-sway velocity time series. However, almost all power spectra of both groups appeared in the low frequency band. The present results suggested frequency characteristics of healthy people occur in the low frequency band, but the elderly group compared with the young adults had more characteristics in the high frequency band. Their frequency characteristics cannot be properly evaluated by the international standard established to screen disorders. It may be necessary for healthy people to have new evaluation frequency sections when considering power spectrum characteristics of sway time series and sway-velocity time series.

Influence of Alcohol Intake on the Parameters Evaluating the Body Center of Foot Pressure in a Static Upright Posture

To examine the influence of alcohol intake on various parameters evaluating the change in body center of foot pressure during a static upright posture, 11 healthy young males and females gave measures of blood pressure, heart rate, whole body reaction time, standing on one leg with eyes closed, and body stability for 60 sec. in the Romberg posture (open eyes, closed feet) before and after the alcohol intake. The measurement was made with an Animas stabilometer G5500. Data sampling frequency was 20 Hz. The subjects drank alcohol (Japanese sake 540 ml) within 10 min. After 10, 20, and 30 min. of alcohol intake, the same measurements were carried out. 24 parameters with higher trial-to-trial reliability were selected from the following 7 domains: distance, mean center of foot pressure, distribution of amplitude, area, velocity, frequency (power spectrum), and direction (vector) of body-sway and velocity. Parameters for distance, velocity, and area of body-sway significantly changed after alcohol intake, but the mean center of foot pressure and frequency of body-sway were unchanged. It was inferred that the mean center of foot pressure and frequency for body-sway did not change even if a nervous function decreased by the alcohol intake, and an upright posture was maintained by increasing the distance, area, and velocity of body-sway. Further, body-sway tends to increase in the medial/lateral direction as compared with the anterior/posterior direction.

POWER SPECTRUM CHARACTERISTICS OF SWAY POSITION AND VELOCITY OF THE CENTER OF PRESSURE DURING STATIC UPRIGHT POSTURE FOR HEALTHY PEOPLE

This study assessed sex and individual differences in sway-position and velocity power spectra and reliability of power frequency with 30 health young people. The body sway for 1 min. was measured twice over a 1-min. rest. There were no significant sex differences in the spectra. Frequency bands with a large coefficient of variance over 10.0 appeared up to 0.6 Hz. 75% relative accumulated power frequency appeared at 1.10–1.23 Hz in the position and at 2.00–3.05 Hz in the velocity spectra. Most power was in the low frequency band (A and B frequency intervals) of the international standard. Relative accumulated power frequency of position and velocity power spectra was reasonably reliable. It may be necessary to establish a new evaluation frequency interval by direction of sway-position and velocity using relative accumulated power frequency for healthy people.

Comparison of the Body-Sway Characteristics of Young Adults Compared to Healthy Elderly and Elderly with Equilibrium Disorder

The study compared body-sway characteristics of 380 young adults, 342 generally healthy elderly without disequilibrium disorders, and a group of 33 elderly with disequilibrium disorders. Center of foot pressure (COP) was measured for 1 min. using an Animas stabilometer G5500 with a data sampling frequency of 20 Hz. Four high reliability measures were used to evaluate body sway (unit time sway, front-back sway, and a left-right sway, and high frequency band power). Unit time sway, left-right sway, and high frequency band power were significantly larger for the group of elderly with disequilibrium disorders, and smaller for the healthy elderly people and young adults, in that order. Front-back sway was significantly larger in the elderly with disequilibrium disorders and healthy elderly than in young adults. The elderly with disequilibrium disorders had a larger and faster sway than young adults as well as the healthy elderly, particularly in the left-right direction. It appears aging was specifically associated with larger influence on the front-back sway.

Power spectrum characteristics of body sway time series and velocity time series of the center of foot pressure during a static upright posture in preschool children

This study aimed to assess individual and gender differences in power spectra in the body sway time series and sway velocity time series during a static upright standing posture using 30 preschool children and their spectrum distribution characteristics. The center of pressure (COP) movement for 1 min was measured twice with a 1 min rest on an Anima stabilometer. The data sampling frequency was 20 Hz. A power spectrum was calculated by applying a fast Fourier transform to time series data of X (medial/lateral) and Y (anterior/posterior) directions. The coefficient of variation (CV) over 10.0 of power was large (from 0.06 to 1.4 Hz in both directions), and as the frequency increased, the CV decreased. There were significant gender differences in the low frequency bands (less than 2.0 Hz), and almost all power of body sway time series and velocity time series were found in the low frequency bands (A and B sections) of the international standard. Individual differences were also large. The distribution of power spectra of their time series was different in both directions. These results suggest that the evaluation section of the existing international standard cannot properly evaluate periodic characteristics of body sway time series and sway velocity time series of preschool children.

Stimulus Tempos and the Reliability of the Successive Choice Reaction Test

Abstract Uchida, Y, Demura, S, Nagayama, R, and Kitabayashi, T.Stimulus tempos and the reliability of the successive choice reaction test. J Strength Cond Res 27(3): 848–853, 2013—In ball game sports, players demand agility, which is a quick and adequate reaction to various changing stimuli. We developed a “successive choice reaction test” that evaluates such agility. This test requires subjects to be exposed to successive stimuli. Hence, it is very important to select appropriate stimulus tempos. In addition, it is necessary to examine the reliability of a new test. This study examined adequate stimulus tempos and test reliability. Fifteen healthy university students participated in this study. All the subjects conducted a successive choice reaction test with 3 kinds of tempos (1.3, 1.5, and 2.0 seconds). To examine its reliability, the test was conducted again on another day. It was found that any tempo has a high reliability, that their relationships are close, and insignificant time differences exist among the tempos. In conclusion, the successive choice reaction test was judged to be useful with any of the above tempos.