Taiikugaku kenkyu (Japan Journal of Physical Education, Health and Sport Sciences)

There has been increased interest in the motor control ability of the adult human nervous system to reorganize and adapt to environmental changes throughout life. In the last decade, motor evoked potentials (MEPs) in response to transcranial magnetic stimulation (TMS) has been used increasingly as a tool to investigate the above-mentioned neural mechanisms in the intact human cortex. Because the spatial accuracy of the technique is limited, it is considered to be merely a useful indicator at the cortical level, similar to H-reflexes at the spinal level. Based on recent data for these two useful parameters, I review the differences in neurophysiological background between them. In the first section, I review the neural background of H-reflexes at the spinal level, and in the second section, that of MEPs at the cortical level. Finally, using these parameters, I show experimental evidence for neural mechanisms of human motor control.

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A study was conducted to investigate the cardiac autonomic system activity, physical activity, and circadian rhythm of body temperature in children with low waking basal body temperature. Fifty-five boys (aged 9-10 yrs) were evaluated for oral body temperature (OBT) and daily physical activity over a one-week period. Cardiac autonomic nervous system activity was also measured during the same period using a 5-min power spectral analysis of resting heart rate variability. The low temperature group (LOW) was defined as>1 SD below the mean waking OBT (n=6). The 43 individuals with a higher waking OBT score (<1 SD below the mean) served as the control group (C). There were no significant differences in waking time or total sleeping time between LOW and C. However, a low waking OBT, and an insufficient decline in bedtime OBT were observed in LOW. Sympathetic nervous system activity was significantly higher, while parasympathetic nervous system activity was significantly lower in LOW versus C. Daily physical activity was significantly lower in LOW versus C. Our results suggest that reduced parasympathetic nervous system activity and a lower level of physical activity may affect OBT circadian rhythm. Our data also suggest that a low waking OBT may be associated with delayed OBT circadian rhythm.

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Case studies were performed to identify any factors defining life satisfaction among the "old-old" (75 years and older) elderly by quantitatively and qualitatively focusing on participation in physical and sports activities and ability to perform activities of daily living (ADL). In order to obtain information on both ADL and life satisfaction, semistructured interviews were conducted with thirty elderly individuals (16 males and 14 females). The subjects were divided into two physical activity groups : active and inactive. 'Active' subjects were those who exercised regularly (regular exercise : three or more times per week for 20 min or longer), while 'inactive' persons did not engage in physical activity. The subjects ranged in age from 75 to 89 years, with a mean age of 80 years. ADL was a concept developed by Demura et al. (1997) and has been used in Japan as an index of motorrelated fitness. It consists of 12 items, presented in Likert-type (three-point) response format : walking, running, jumping, climbing stairs, standing, changing clothes and sitting up. The summed overall ADL score was calculated, the theoretical maximum being 36. The ADL score among the subjects ranged between 12 and 36, with a mean of 26. The scale of life satisfaction developed by Brown & Frankel (1988), revised by Yamaguchi et al. (1996), was used to measure the degree of life satisfaction. This includes seven items measured by a five-point Likert-type scale : leisure satisfaction, health condition, economic situation, living situation, relationships with friends, relationships with family members and overall satisfaction with life. The summed overall score for life satisfaction has a theoretical maximum of 35. The range of life satisfaction among the subjects was between 20 and 35, with a mean of 30. It is concluded that ADL and life satisfaction among "old-old" active elderly individuals are both high in comparison with the elderly investigated in previous research. However, it appears that life satisfaction among these individuals is also influenced by social support.

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A study was conducted to clarify factors that influence the learning effect of overhand-throwing, focusing on physical fitness and throwing motion before learning. Twenty-two boys and 24 girls in the second grade of elementary school, and 24 boys and 29 girls in the fifth grade carried out a learning program comprising four kinds of teaching materials. To improve their throwing motion, they carried out the program seven times for 15-20 min as a physical education class during a three-week period. Tennis ball throwing distance was measured, and the subjects' throwing motions were video- taped and evaluated by the observation method. At the same time, physical fitness and imitation ability were tested. As there was no significant correlation between the learning effect of throwing motion, and physical fitness and imitation ability in the group of second grade girls, it was thought that proper acquisition of throwing motion led to the improvement of throwing distance. In the group of fifth grade boys, those with a lower physical fitness level showed a large throwing motion learning effect. In the second grade boys and fifth grade girls groups, the imitation ability of the lower limb was one of the factors that influenced the learning effect. These results suggest that proper motor learning of overhand throwing has the possibility of improving throwing ability, and that some conditions present before learning, such as throwing motion, physical fitness and imitation ability, influence the degree of the learning effect.

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