Biomedical subjects

Shinichi Demura

Publications and source records attributed to Shinichi Demura.

At least 19 recordsLinked to original sources

PubMed2006

Residual volume on land and when immersed in water: effect on percent body fat.

There is a large residual volume (RV) error when assessing percent body fat by means of hydrostatic weighing. It has generally been measured before hydrostatic weighing. However, an individual's maximal exhalations on land and in the water may not be identical. The aims of this study were to compare residual volumes and vital capacities on land and when immersed to the neck in water, and to examine the influence of the measurement error on percent body fat. The participants were 20 healthy Japanese males and 20 healthy Japanese females. To assess the influence of the RV error on percent body fat in both conditions and to evaluate the cross-validity of the prediction equation, another 20 males and 20 females were measured using hydrostatic weighing. Residual volume was measured on land and in the water using a nitrogen wash-out technique based on an open-circuit approach. In water, residual volume was measured with the participant sitting on a chair while the whole body, except the head, was submerged . The trial-to-trial reliabilities of residual volume in both conditions were very good (intraclass correlation coefficient > 0.98). Although residual volume measured under the two conditions did not agree completely, they showed a high correlation (males: 0.880; females: 0.853; P < 0.05). The limits of agreement for residual volumes in both conditions using Bland-Altman plots were -0.430 to 0.508 litres. This range was larger than the trial-to-trial error of residual volume on land (-0.260 to 0.304 litres). Moreover, the relationship between percent body fat computed using residual volume measured in both conditions was very good for both sexes (males: r = 0.902; females: r = 0.869, P < 0.0001), and the errors were approximately -6 to 4% (limits of agreement for percent body fat: -3.4 to 2.2% for males; -6.3 to 4.4% for females). We conclude that if these errors are of no importance, residual volume measured on land can be used when assessing body composition.

Adult↗

PubMed2006

Comparison in the effect of linear polarized near-infrared light irradiation and light exercise on shoulder joint flexibility.

OBJECTIVE: This study aimed at comparing the effect of linear polarized near-infrared light irradiation (PL irradiation) and bicycle exercise with 50%HRreserve on the flexibility of the shoulder joint. DESIGN: Placebo-controlled trial. SETTING: Twenty-four healthy young adults (10 males: mean+/-SD, age 20.9+/-3.1 y, height 171.0+/-3.9 cm, body mass 63.4+/-3.5 kg and 14 females: age 21.2+/-1.7 y, height 162.0+/-7.8 cm, body mass 56.2+/-7.2 kg). INTERVENTIONS: PL-irradiation (100%, 1800 mW), placebo-irradiation (10%,180 mW), and light exercise (50%HRreserve) for 10 minutes. OUTCOME MEASUREMENTS AND RESULTS: The shoulder joint angles were measured twice-before and after each intervention. We measured the angles when the right shoulder joint extended forward and flexed backward maximally without support, and analyzed these shoulder joints and range of motion. Trial-to-trial reliability (intraclass correlations) of each joint angle was very high, over 0.98. All joint angles showed significant changes, and values in post-PL-irradiation and postlight exercise were significantly greater than that in postplacebo-irradiation. Shoulder forward flexion and backward extension angles had significantly greater change rates in PL-irradiation and light exercise than placebo-irradiation, and their range of motion angle was in the order of PL-irradiation, light exercise, and placebo-irradiation. CONCLUSIONS: It is suggested that PL-irradiation produces almost the same effect on shoulder joint range of motion as light exercise.

Adult↗

PubMed2006

The influence of different target values and measurement times on the decreasing force curve during sustained static gripping work.

The purposes of this study were to clarify the decreasing properties of, and to examine useful measurement times for evaluating muscle endurance in a comparison among various parameters using measurement times of 1, 3 and 6 mins and target values of 50, 75 and 100% MVC. Fifteen males and 15 females participated in this study. All subjects carried out sustained isometric gripping under nine conditions of measurement times and target forces, (1, 3 and 6 mins vs. 50, 75 and 100% MVC) with an interval of one or two days. The property of decreasing force in the initial phase (marked decreasing phase) differed among the target values, and the decreasing speed of the gripping force was highest for 100% MVC. However, the decreasing property after about 60 sec, in which the force decreased to about 30% MVC from the onset of grip, was similar among all target values, and then the gripping force reached an almost steady state phase at about 150-180 sec. In other words, the difference of the decreasing property during the initial phase with different target values was considered not to influence the property in the later phase, in which the force decreases to about 30% MVC. When muscle endurance is evaluated from the phase until reaching the steady state, it may be possible to evaluate the same property of the decreasing phase at 6 min as the measurement at 3 min. The measurement for 1 min at 50% MVC was not valid as an evaluation time because the grip force did not decrease enough. The integrated area in the initial phase was considered to depend on the magnitude of the target value, and the integrated area for 30 sec or 60 sec at 75% MVC was larger than that at 100% MVC. It was inferred that higher pain at 100% MVC resulted in a greater decrease in the speed of the force.

Adult↗

PubMed2006

Muscle power output properties using the stretch-shortening cycle of the upper limb and their relationships with a one-repetition maximum bench press.

The purpose of this study was to examine the output properties of muscle power by the dominant upper limb using SSC, and the relationships between the power output by SSC and a one-repetition maximum bench press (1 RM BP) used as a strength indicator of the upper body. Sixteen male athletes (21.4+/-0.9 yr) participated in this study. They pulled a load of 40% of maximum voluntary contraction (MVC) at a stretch by elbow flexion of the dominant upper limb in the following three preliminary conditions: static relaxed muscle state (SR condition), isometric muscle contraction state (ISO condition), and using SSC (SSC condition). The velocity with a wire load via a pulley during elbow flexion was measured accurately using a power instrument with a rotary encoder, and the muscle power curve was drawn from the product of the velocity and load. Significant differences were found among all evaluation parameters of muscle power exerted from the above three conditions and the parameters regarding early power output during concentric contraction were larger in the SSC condition than the SR and ISO conditions. The parameters on initial muscle contraction velocity when only using SSC significantly correlated with 1 RM BP (r=0.60-0.62). The use of SSC before powerful elbow flexion may contribute largely to early explosive power output during concentric contraction. Bench press capacity relates to a development of the above early power output when using SSC.

Adult↗

PubMed2006

Contribution of physical fitness component to health status in middle-aged and elderly males.

This study determined the physical fitness component that contributes to improving and maintaining health status for each age group as well as quantifying the degree of the relationship between health status and physical fitness in middle-aged and elderly males. The participants were 995 males aged 30 to 69 years. Ten physical fitness tests and medical checkups were performed. The participants were divided into a healthy group and an unhealthy group according to health status. Multiple discriminant analysis was applied to the multivariate data. Correct discriminant probabilities of the multiple discriminant function to discriminate the healthy and unhealthy groups for males ranged from 67.0% to 75.1%. These findings suggest that there is a relatively high relationship between the health status and physical fitness level for middle-aged and elderly males. With each individual's discriminant score calculated using the multiple discriminant function as the index of the degree of health, the Pearson's correlation coefficient of the discriminant score and the performance in each physical fitness test were calculated. The age change between 30 and 69 years old was classified into five patterns according to the contribution. The result of this study is considered to be useful as objective data to prepare an exercise program considering the contribution of the physical fitness component of health status.

Adult↗

PubMed2006

The influence of gender, athletic events, and athletic experience on the subjective dominant hand and the determination of the dominant hand based on the laterality quotient (LQ) and the validity of the LQ.

This study aimed to reveal the influence of gender, athletic events and athletic experience on the subjective dominant hand and the dominant hand based on the laterality quotient (LQ). It also aimed to examine the validity of the Edinburgh Inventory (Oldfield, 1971). Males and females (n=3,726) living in 7 prefectures in Japan (age: 16-45 yrs) participated in this survey. Analysis was performed on 3,557 separate datasets with high reliability. The reliability of the survey was examined using a test-retest method consisting of 100 people selected randomly from all participants. All participants provided the same answers for each question. The influence of gender, event and experience was examined for the subjective and LQ-based dominant hands. In addition, concordance rates of the subjective dominant hand and the LQ-based dominant hand and both dominant hands were examined. Differences of concordance rates between hands used in the 10 movement questions of the Inventory and the subjective dominant hand were tested using the chi(2) test. The frequency differences among items were tested using Ryan's method (multiple comparisons). Significant gender differences were found between rates of the LQ-based dominant hand (males: 94.4%; females: 96.6%) and the subjective dominant hand (males: 91.6%; females: 94.0%), but the degree was only 2.0-4.0%. Insignificant differences were found among athletic events, two groups of different athletic experience, and gender according to each athletic event. The subjective dominant hand almost always agreed with the LQ-based dominant hand (complete concordance rate=0.96, kappa=0.67). Of the 10 question items, inexperienced answers were found only in the item "Knife (without fork)". The "Toothbrush", "Broom (upper hand)", and "Opening box (lid)" items had significantly lower correspondence with the subjective dominant hand (79.7-87.0%) than the other items (92.1-95.7%). In conclusion, athletic experience appears to have little influence on handedness, although there is a slight gender difference. The subjective dominant hand almost always agrees with the dominant hand based on the Inventory. A more efficient handedness inventory may be constructed by excluding the above 4 items.

Adolescent↗

PubMed2006

An examination of practice and laterality effects on the Purdue Pegboard and Moving Beans with Tweezers.

The purpose of this study was to examine the relation of practice or learning and laterality on the Purdue Pegboard and the Moving Beans with Tweezers test. The subjects were 30 right-handed, healthy young male adults (age: M = 21.1, SD = 1.9 yr.). The subjects performed both tests five times with each hand. A two-way analysis of variance (hand x trial) for scores on the Purdue Pegboard showed that Trial 1 had a significantly lower mean than Trials 4 and 5 with the dominant hand, and scores on Trials 1 and 3 were lower than that on Trial 5 for the nondominant hand. For the Moving Beans with Tweezers test, Trial 1 had a significantly lower score than Trial 5 with the nondominant hand. The dominant hand produced significantly higher values on all trials of both tests. Intraclass correlation coefficients of Trials 2 and 3 were high, and means were significantly higher for the dominant hand. A correlation between other tests was not high (r = .37-.46) for both hands. All correlations among five trials on both tests were significant and high (Purdue Pegboard-Dominant: average r =.72, [r] = .60-.80, Purdue Pegboard-Nondominant: average r = .59, [r] = .43-.76), (Moving Beans-Dominant: average r = .74, [r] = .57-.81, Moving Beans-Nondominant: average r =.71, [r] = .55-.87). Correlations among five trials for the ratio of dominant:nondominant hand on both tests were significant and moderate (Moving Beans: average r = .28, [r] = .08-.57, Purdue Pegboard: average r = .41, [r] = .19.56). Performance with the dominant hand is superior to that of the nondominant hand on both tests. Practice effects are found for both tests across five trials. The Moving Beans with Tweezers test also showed laterality of practice effects. The two tests may measure different abilities.

Adult↗

PubMed2006

Influence of differences of visual acuity in various visual field conditions on spectral characteristics of the center of pressure sway.

This study examined the influence of visual acuity and visual field on the spectral characteristics of the center of pressure during standing. 17 men and 20 women participated in High and Low visual acuity groups. Both groups underwent center of pressure measurements under three visual field conditions: No vision: subjects were given no visual information, Central vision: they were given only central visual field information, and Full vision: they were given full visual information. To assess the spectral characteristics of center of pressure, mean power frequency and frequency of maximal power were calculated from medial-lateral and anterior-posterior center of pressure directions. The Friedman test and Scheffé pairwise comparison tests showed that frequency of maximal power was higher in the No vision than in the Central and Full vision conditions in the High visual acuity group. In conclusion, people with high visual acuity are more susceptible to visual field conditions than those with low visual acuity. It is suggested that postural control characteristics differ with visual acuity or resolution in the central visual field.

Adult↗

PubMed2006

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.

Aged↗

PubMed2005

Prediction equation for head volume of Japanese young adults.

Accurate measurement of head volume is indispensable for precise assessments of body composition determined by hydrostatic weighing without head submersion. The purpose of this study was to establish a prediction equation for head volume measured by the immersion method from multiple regression analysis using head parameters (head circumference, head length, head breadth, neck girth and head thickness) as independent variables. The participants were 106 Japanese young adults (55 males and 51 females) aged 17-27 years. Intra-class correlation coefficients (ICCs) for each head parameter and head volume in males and females were very high (ICC = 0.993-0.999, 0.992-0.998). Head circumference was closely related to head volume measured by the immersion method (r = 0.719, 0.861, P < 0.05), and was the most important parameter for the prediction equation in both sexes. Head breadth was related poorly (r = 0.475, 0.500, P < 0.05) and showed a small individual difference. It was, therefore, excluded from the independent variables. The prediction equation for males was predicted head volume = 122.10X1 + 106.19X3 + 37.16X4 - 89.46X5 - 4754.93, R = 0.909, SEE = 121.75 ml, and that for females was predicted head volume = 213.83X1 + 45.24X3 + 36.85X4 - 74.34X5 - 8912.43, R = 0.913, SEE = 136.26 ml (where X1 = head circumference, X3 = head length, X4 = neck girth, X5 = head thickness, and SEE = standard error of the estimate). The limits of agreement for predicted and measured head volume were -234.5 to 234.1 ml for males, and -261.0 to 261.0 ml for females. In cross-validation groups of both sexes, there were no significant differences between measured head volume and predicted head volume. The correlation coefficients between measured head volume and predicted head volume in males and females were 0.894 and 0.908, respectively. The predicted head volume from prediction equations was considered to have high reliability and validity.

Adolescent↗

PubMed2005

Examination of the reproducibility of grip force and muscle oxygenation kinetics on maximal repeated rhythmic grip exertion.

The contribution of physiological mechanisms involving force-exertion value during maximal repeated rhythmic muscle contraction work changes over time. The purpose of this study was to examine the reproducibility of grip force and muscle oxygenation kinetics with a decrease of the gripping force during maximal repeated rhythmic grip (RRG). Subjects were 10 males, aged 20-26 years (height 173.9+/-7.3 cm, body weight 71.5+/-11.2 kg). Each subject performed maximal repeated rhythmic grip as a target value with a target frequency of 30 grips.min(-1) for 6 min. The trial-to-trial reproducibility of Oxygenated haemoglobin (Oxy-Hb), Deoxygenated haemoglobin (Deoxy-Hb), Total haemoglobin (Total Hb) and grip force during the RRG (6 min) was very high (r(xy)=0.919-0.966) and the decreasing pattern of the force-time curve was consistent. The cross correlation coefficients of the grip force (r(xy)=0.985) and muscle oxygenation kinetics (Total Hb: 0.996, Oxy-Hb: 0.992, Deoxy-Hb: 0.995) in the pre-inflection phase (marked force decreasing phase) were very high, while these coefficients in the post-inflection phase (almost steady state phase) were low as compared with those in the pre-inflection phase. The trial-to-trial reliabilities of any parameter regarding grip were fair or high (ICC=0.686-0.927). The changing points of muscle oxygenation kinetics appeared before reaching an almost steady state, which showed a high reliability and they were considered to reflect the shift of physiological mechanisms. In particular, the intraclass correlation coefficients (ICC) for the time to reach maximum Deoxy-Hb and Oxy-Hb values and regression coefficient in an increasing phase of Oxy-Hb were very high (ICC=0.894-0.947). It was found that the trial-to-trial reproducibility of grip force and muscle oxygenation kinetics is very high during the whole 6 min in RRG, but is poor during the post-inflection phase. The reproducibility of the grip force and muscle oxygenation kinetics in the phase before reaching an almost steady state during RRG is fair, and the decrease of the grip force in this phase may be influenced by the muscle oxygenation kinetics.

Adult↗

PubMed2005

Optimum onset period for training based on maximum peak velocity of height by wavelet interpolation method in Japanese high school athletes.

The Wavelet Interpolation Method (WIM) was applied to the longitudinal records of individuals' heights and weights from 6 to 17 years of age (1983 to 1994) in an athlete group (male: 45, female: 50) and a control group (male: 85, female: 85). The criterion of maturity was derived from age at Maximum Peak Velocity (MPV) of height in the control group. Ages at MPV of height and weight were compared between the athletes and control subjects. The WIM was also applied to mean heights from 6.5 to 17.5 years of all the subjects classified by maturation rate in order to derive a model of growth velocity types. Among the athletes, the males were early-maturing and the females tended to be late-maturing. The difference between the ages at MPV of height and weight in males and females was less in the athletes group than in the control group. For the growth velocity model, in the athlete group, three types could be confirmed among the males, and five among the females. By making use of the type models, it was possible to clarify the spans of adolescence as classified by maturation rates, and it was concluded that the period following the age at MPV seems appropriate for the introduction of regular athletic training for each level of maturity.

Adolescent↗

PubMed2005

Effect of Japanese sitting style (seiza) on the center of foot pressure after standing.

Seiza is one of the most commonly used sitting postures in various enrichment lessons of Japanese origin. It is reported that Seiza with large knee flexion produces harmful effects on the cartilage of knee joints and hemodynamics of the lower legs. This study aimed at examining the influence of Seiza on tissue oxygenation kinetics of the lower limbs, plantar somatic and cutaneous sensation, and the center of foot pressure (COP) sway using 10 young adults. COP sway was measured for 1 min just after sitting on a chair for 10 min (pre-test), after 30-min Seiza (post-test 1), and 5 min after Seiza (post-test 2). To evaluate the COP sway, we used 4 body sway factors; unit time sway factor (F1), front-back sway factor (F2), left-right sway factor (F3) and high frequency band power spectrum factor (F4). Physiological parameters (i.e., tissue oxygenation kinetics in the lower legs and sensation on the sole) were measured during 30-min Seiza (continuously on tissue oxygenation, and at 1 min intervals on sensation), and for 1 min just before each COP test (pre-test, post-test 1 and 2). Oxygenated hemoglobin/myoglobin (Hb/Mb) concentration decreased markedly and deoxygenated Hb/Mb concentration increased markedly, resulting in reaching a plateau state at around 7 min. Tissue Hb/Mb index changed little during Seiza. Proprioceptive perception thresholds increased rapidly about 17 min after Starting Seiza. Means of 3 COP sway factors of F1, F2 and F4 were significantly higher in post-test 1 than in pre-test and post-test 2. In conclusion, a marked decrease in tissue oxygen concentration of the lower legs within 4-5 min, and an increase of proprioceptive perception thresholds in the sole at about 17 min are induced by Seiza. Although wiggle and quick body sway in the antero-posterior axis increases markedly in an upright posture just after maintaining Seiza for 30 min, sway recovers after sitting on a chair for 5 min.

Adult↗

PubMed2005

QOL models constructed for the community-dwelling elderly with ikigai (purpose in life) as a composition factor, and the effect of habitual exercise.

The purpose of this study was to construct QOL models for the elderly that included ikigai as a composition factor and to clarify differences in two kinds of models, one constructed for the elderly with habitual exercise and the other for those without it. The subjects were 1,566 healthy community-dwelling independent people aged 60 years or more (752 males, 814 females). First, the ratio of subjects with ikigai was calculated. The ratios of subjects with different kinds of objects of ikigai were also calculated. Next, structural equation models (SEM) were constructed on the basis of social, physical, and mental QOL and ikigai. Fits of the models were evaluated. To examine whether the presence or absence of habitual exercise caused any difference in the QOL model, subjects were divided into 4 groups according to whether they were male or female and whether they had or did not have an exercise habit. Multi-population group simultaneous analysis was then performed among the four groups. More than 85% of the subjects had objects of ikigai. Ikigai is an important factor for comprehending the QOL of the elderly. It was possible to construct QOL models for the elderly with ikigai as a composition factor. The effect of physical QOL on mental QOL was negligible in females irrespective of whether they had an exercise habit. The effect of social QOL on mental QOL was profound in aged females with an exercise habit. The effect of the living situation on mental QOL was profound in aged females without an exercise habit. The effect of mental QOL on ikigai was more marked in subjects without an exercise habit than in those with an exercise habit.

Aged↗

PubMed2005

Body sway characteristics during static upright posture in healthy and disordered elderly.

This study aimed to compare body sway characteristics of the healthy elderly and the disordered elderly. The subjects were 38 healthy elderly and 24 disordered elderly with disequilibrium. The latter consisted of two groups: 12 elderly with vestibular organ or central nervous systems disorder (central nervous disorders), and 12 elderly with disorder in other systems (other disorders). The measurement device can calculate the center of foot pressure (CFP) of vertical loads from the values of three vertical load sensors, which are located at the corners of an isosceles triangle on a level surface. The data sampling frequency was 20 Hz. Four body sway factors with high reliability (unit time sway, front-back sway, left-right sway, and high frequency band power) were used to evaluate body sway. As compared with healthy people, central nervous disorders had larger unit time sway, high frequency band power, and left-right sway factors. Other disorders were larger in unit time sway and high frequency band power factors. Central nervous disorders, as compared with other disorders, had larger unit time sway and left-right sway factors. Disorders produced large and fast sway, and central nervous disorders in particular showed a marked sway in the left-right direction. The existence of disease influenced body sway more than decline in various functions related to posture control with aging, because even with the same elderly, disorders showed a larger body sway.

Aged↗

PubMed2005

The practice effect and its difference of the pursuit rotor test with the dominant and non-dominant hands.

The purpose of this study was to examine the practice effect and what difference it makes in the pursuit rotor test for the dominant and non-dominant hands in 30 right-handed Japanese male adults aged 18 to 23 years (Age 20.8+/-1.4 yrs). The subjects performed the pursuit rotor test for 1 min in 20 trials with a 1-min interval alternately using the dominant and non-dominant hands. After continuing for 10 trials, a 5-min rest was taken. The measurement order was randomly assigned. Contact time of a steel pen and a target was measured in units of 1/10 sec. The measurements showed a constant increasing tendency at every trial until the 6th trial in both hands. Significant linear regressions were identified, but the increase-rate of the dominant hand was significantly larger. Individual differences showed a decreasing tendency at every trial in the dominant hand, but in the non-dominant hand it increased until the 4th trial then decreased. The relationships between measurements of the 1st and 10th trials in both hands and both hands in the 1st or 10th trial were not high. The performance of the pursuit rotor test improves at every trial in both hands, but the improvement rate decreases after the 7th trial. The improvement rate of the dominant hand is high. The change in individual differences differs in both hands and the relationship between the measurements is not high. It can be judged that the practice effect of the pursuit rotor test differs in the dominant and non-dominant hands.

Adolescent↗

PubMed2005

Controlled exertion of force by developmentally delayed young men and women.

Present purposes were to examine the characteristics of controlled force exertion in 28 developmentally delayed young people (14 men, 14 women), and sex differences compared to 28 normal young students (14 men, 14 women). The subjects matched their submaximal grip strength to changing demand values displayed in a bar chart on the display of a personal computer. The total sum of the differences between the demand value and grip exertion value for 25 sec. was used as an evaluation parameter for the test. The controlled force exertion was significantly poorer for he developmentally delayed group than for controls, and there were large individual differences. The developmentally delayed men scored poorer than women in coordination. Like the controls, the means between trials did not decrease significantly. For these developmentally delayed subjects, performance did not improve after only a few trials. The controlled force-exertion test is useful as a voluntary movement-function test for developmentally delayed subjects.

Adolescent↗

PubMed2005

Instruction in reliability and magnitude of evaluation parameters at each phase of a sit-to-stand movement.

The sit-to-stand movement strategy of each subject is different depending on whether the subjects perform voluntary movements or have concrete instructions (i.e., stand quickly), which is strongly reflected in the performance of each sit-to-stand movement phase. Thirty young-adult male subjects participated in this study (M age=20.7 yr; SD=2.6). Subjects performed the two movements from a chair height adjusted to the subject's lower thigh length. In the self-administered (SA) condition, subjects voluntarily stood up from the chair without instruction, and in the assigned-ordered (AO) condition subjects stood up from the chair as fast as possible. Vertical floor reaction force and electromyograms of the rectus femoris and tibialis anterior muscles were measured, and 15 parameters were selected. The parameters in the phase between the peak value of the floor reaction force and completion of the movement was highly reliable regardless of instruction. However, other parameters had different reliabilities between the instruction conditions. In particular, the parameters in the phase between starting the movement and the peak value of the floor reaction force under the assigned-order were higher than those of the self-administered condition. Moreover, the sit-to-stand movement was conducted faster in the assigned-order condition during the phase between starting the movement and buttocks-syneresis, and the peak value of the floor reaction force and completion of the movement. From the above, in the assigned-order condition "as fast as possible," the anteflexion bending movement and extension of knee and trunk joints were faster, and anteflexion movement was repeated more similarly under a concrete instruction such as moving as fast as possible.

Adolescent↗