As children age , motor performance improves . There are many variables discussed in the development literature to which these changes in performance are attributed. Those mentined most frequently are physical growth, biomechanical and physiological factors. Overviews of these factors have been presented elsewhere (cf. Thomas. 1980). Reaction time experiments have often been used to investigate developmental variables affecting the motor output Process (Furui, Seki and Kasai, 1983). In normal subjects, the premotor reaction time (PMT) of the biceps brachii has been determined to be different in flexion (F) and supination (S)of the forearms. Accordingly, because the same muscles performs in both functions and PMTs of those two different movement patterns are definitely different, this would suggest that these two voluntary movements would be separately organized in the brain (Kasai, 1983, 1984). The present experiments are therefore undertaken to examine the developmental changes and sexual differences of these motor output systems by means of those reaction time tasks and collect information with respect to which these changes in performance are attributed. The subjects for the present study are 100 male children (20 subjects from seven to eleven years old, respectively) and 98 female children (20 subjects in each age category, except nine-years old). They were all right-handed. The tasks of the subject were the F and the S of right forearm only, responding to a sound signal as quickly as possible. Mechanical reaction timed (MRTs) of the F and the S were measured with the digitimer. The premotor reaction times (PMTs) of both movement patterns with the surface EMG of the biceps brachii among the nine, ten and eleven years old groups, respectively were also measured. As the regression coefficience of MRT and PMT in the F and the S were extremely significant (Furui, Seki and Kasai, 1983), motor times (MTs) were obtained by subtracting PMTs from MRTs. The main findings in the present study are summarized as follows: 1. MRTs of mrile and female children shortened in both movement patterns as they grew older. Those phenomena were especially noticeable between seven and nine years old. 2. MRTs of the F were always shorter than those of the S. However, MRT differences between two movement patterns disappeared at eleven years old. 3. MRTs of male children in both movement patterns were always shorter than those of female children. Since PMTs of male and female children in both movement patterns were not different, the reason why MRTs were different between both sexes was the differences in MTs (peripheral motor functions). 4. PMTs which mean central motor functions (motor pattern generator) were not different for both sexes among the nine , ten and eleven years o1d group , but this function appeared earlier for the female than for the male. However, this function of the male was superior to that of the female from ten years old. From the present results, two different motor functions (motor output and motor pattern generators) were considered which showed the developmental changes of reaction times in two different movement patterns.

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Controllability of motor imagery is one of the critical factors for the effectiveness of mental practice. It is generally defined as the ability to control or manipulate motor imagery menta1ly. In this study, a new test to measure the controllability of motor imagery (CMI test) was developed and its validity and reliability were examined. The CMI test was constructed from 15 different tasks with the following five imagery controls per one task. University students were required to image a basic movement pose and then to control or manipulate its imagery successively according to the instruction. After the five successive control, the subjects were asked to choose the last movement pose in their imagery out of five different poses (pictures) by using the recognition method. First of all, split-half and test-retest reliability estimates were obtained for the CMI test. Cron-bach'sα coefficient (an estimate of internal reliability) was 0.731 and test-retest reliability with the two months interval was 0.728. Validity of the CMI test was examined from the following three viewpoints: (1) comparison of the CMI test score between gymnastic and non-gymnastic groups; (2) relationship between the CMI test and Gordon Test of Visual Imagery Control; and (3) effect of the CMI test score on a learning sequential movement pattern. All of these results were successful in validating the CMI test. It was considered that utility of the newly developed test for controllability of motor imagery might hold sufficient expectations, though several further empirical works were needed to generalize the validity of the CMI test.

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This study was attempted to realize the characteristics of physical growth and development of the visually handicapped children. The semi-longitudinal data set of 8 physique and motor ability items were collected from the visually handicapped children of the attached blind school of University of Tsukuba. Then, these data were classified into three groups in terms of degree of visual handicap: totally blind, severe partially sighted, and mild partially sighted. The mean of each physical attribute was converted into H-score for each age respectively, using the mean of measns of 6 through 17years old of normally sighted children and its standard deviation. The following conclusions were induced. The physique growth patterns of visually handicapped children were very similar to those of the normally sighted children, but, during the term of growth accelaration, the relative differences between physique elements tended to decrease in the visually handicapped, but increase in the normal. In the visually handicapped, each motor skill showed some unique trend of development, and the relative differences were found very significant between different motor skill elem6nts in all ages, but the normally sighted children showed some considerably similar trend of development and small extent of differences between different motor skill elements in all ages. In the visually handicapped, however, such great deal of differences tended to decrease according to the age increase, but the mild partially sighted children showed smaller differences between different motor skill elements than the totally blind and the severe partially sighted in a1l ages: Then, such differences were larger in girls than boys.

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This study was designed to investigate the relative contribution of motor ability elements to fundamental motor ability and its change due to age increase. The physique test (4 items) and sport test (developed by the Ministry of Education, Science and Culture) were carried out annually in grades 10-12, using five sample groups (the total sample size was 1,897 high school students; 892 boys and 1,005 girls) enrolled in K senior high school in the period of 1970-1974. The above data were analyzed using a factor analysis procedure in each grade and each sex, respectively. Judging from the results of the variance ratio of each ability element extracted as factor to the fundamental motor ability area and its change due to age increase, the following conclusions were obtained. 1. In both boys and girls of all five sample groups, it could be inferred that the physique elements such as stature, sitting height, weight, and chest girth, greatly contributed to the fundamental motor ability. 2. In both boys and girls of all five sample groups, no consistent trend due to age increase was shown in terms of the degree of contribution of their motor ability factors. 3. On the degree of contribution of each motor ability subdomain extracted as factor to a total variance, the comparison between boys and girls of all five groups showed no significant difference, and no significant difference was observed between five sample groups on the degree of contribution of each motor ability subdomain to a total variance. 4. Judging the mean degree of contribution of motor ability subdomain, it was inferred that there would be no significant variation due to age increase in the degree of contribution of each motor ability subdomain to fundamental motor ability. 5. When comparing fundamental motor abilities between boys and girls, a certain significant difference was shown in muscular strength and in flexibility. However, three subdomains such as body bulk, body linearity and fundamental motor skill were extracted in boys and girls. It seems that. only 10 to 11% of total variance could be explained by muscular strength and flexbility subdomains which showed sex difference in the factorial structure of fundamental motor ability.

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[in Japanese]

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The purpuse of this study was to clarify the mechanism of movement of the lower limbs as to the increase of running speed. Six subjects (3 trained and 3 untrained) were employed in this study. In order to analyze the mechanism, Fourier transform method was used. The results were summarized as follows: 1) As the running speed increased, values of constant and amplitude of the thigh angle were increased. This means that the center of swinging movement of the thigh shifted foward and its amplitude increased as the running speed increased. 2) As the running speed increased, the amplitude of the hip torque increased and the initial phase of the hip torque shifted foward. This result suggested that in accordance with the increasing of running speed, the hip joint must generate not only big torque but also change the pattern of the torque. 3) In relation of torque to angular velocity and angle at the hip joint, it was indicated that angular velocity reached to the maximum just before torque became 0, and that the torque showed maximum negative when the angle became maximum positive. 4) Amplitude of the hip torque and the knee torque were increased as the running speed in. creased, but the increase rate of the hip torque was bigger than that of the knee torque.

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