Objective: The purpose of this study was to investigate the effect of pubertal maturation stage on development bone mass and body composition.
Subjects and methods: Healthy 149 Japanese junior high school students (75 boys and 74 girls) were participated in the study. We measured transmission index (TI) and speed of sound (SOS) at the calcaneus using a quantitative ultrasound AOS-100 instrument (ALOKA Co., Ltd, Tokyo), height, weight and percentage of body fat by the bio-impedance method using TBF-300 (TANITA Co., Ltd, Tokyo). Five measurements were performed every three months for a year. Girls reported the age at menarche by the questionnaire.
Results: The girls before menarche achieved higher increase in height, meanwhile those over one year after menarche did not achieve any increase. In both boys and girls, it was speculated that the degree of increase in height indicated the stage of pubertal maturation. So we divided the subjects into three groups of pubertal maturation by the degree of increase in height and performed statistical analyses of TI and SOS between three groups. In boys, less SOS value was obtained in the subjects at later stage of pubertal maturation while increases in TI were not statistically different between three groups. All three groups of girls showed the same degree of increase in SOS but no significant increase in TI.

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The authors report few findings concerning estimation of specific body surface area (: s=body surface area/body weight) in early elementary school years and that of age at peak height velocity (: PHV) of stature that appears when assessing the standard values for longitudinal 1/s according to rate of maturity.
The subjects of the study were 81 boys for whom data concerning stature and weight measured in April each year from elementary school to high school was obtained. Those who participated in extracurricular sports less than 3 days per week for both high school and middle school were considered nonathletes.
Those who participated in extracurricular sports 5 days a week or more were considered athletes. The data included stature and weight measured in April each year from elementary school to high school for 74 subjects that participated in rugby beginning in junior high school and 56 who participated in boxing beginning in high school.
Standard charts according to longitudinal maturity type of 1/s were used for estimation of 1/s.
As a result, rank correlation of 1/s in early elementary school years and that of age at PHV of stature in non-athletes was 0.634; a significant correlation of 1% level was observed.
The values of 0.805 for those participating in rugby and 0.826 for those participating in boxing were both higher than the rank correlation factor for non-athletes who were subjects of the study.
When examining longitudinal 1/s of individuals whose estimation for early elementary school years was below the 25 percentile curve and above the 75 percentile, it was observed to increase with age and a difference in 1/s was observed in individuals of the same age, with the value being higher for athletes than for non-athletes.

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The purpose of this study was to make clear the relationship between sleeping habits and sleeping problems and/or physical discomforts among junior high school students. The subjects were comprised of 146 boys and 170 girls in three public junior high schools. The investigation was carried out by a questionnaire in September 2003. The questionnaire contained questions about the time subjects go to bed, time subjects wake up, sleeping problems and physical discomfort. The main findings were as follows: 1) The time subjects go to bed becomes later with increasing age among both boys and girls (p<0.05). Meanwhile, the fluctuations in time to bed showed no significant differences according to sex or grade. 2) The group who went to bed late had significantly higher values for sleeping problem scores and physical discomfort scores (p<0.05). 3) The sleeping problem scores according to fluctuations in time to bed were: for the low fluctuations group, 12.5±13.7 points, 18.7±17.2 points for the middle fluctuations group, and 24.3±20.5 points for the high fluctuations group. The sleeping problem scores for the high fluctuations group were significantly higher than it was for the low fluctuations group (p<0.05). 4) The physical discomfort scores were 20.1±29.8 points for the low fluctuations group, 29.5±30.3 points for the middle fluctuations group and 41.3±30.2 points for the high fluctuations group. The physical discomfort scores for the high fluctuations group were significantly higher than those for the low and middle groups (p<0.05).
From the above, it was shown that there is a need for the regulation of time to bed to be added to traditional health education.

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