To investigate the relationship between age at beginning of training, onset of menarche, distance for training of running, and lumbar bone mineral density (LBMD), twenty-six female long distance runners aged 18years old and above were examined. Runners suspected primary amenorrhea were excluded in this study.
Runners who started training before menarche were delayed their onset of menarche significantly. The age at onset of menarche was selected as determining factor for LBMD, and was significantly negatively correlated to LBMD. It should be important not to delay menarche for preventing low LBMD in female long distance runners.

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In the present study, the change in BMI with age was examined by applying the wavelet interpolation method (WIM), and the maximum peak velocity (MPV) of BMI was derived from the growth (aging) distance curve of BMI. We investigated the association between the age at menarche and MPV of BMI. In Addition, the critical period for body fat mass at the occurrence of menarche was estimated. Data were obtained from 87 female non-athletes in their third year at high school in the Tokai area. Health examination records showing these subjects'heights and weights from the first grade of elementary school to the final year of high school (1990-2002) were collected and BMI was calculated for each grade. Ages at menarche were ascertained from questionnaires. The age at MPV of BMI (12.19±1.35 years old) was almost the same as the age at menarche (12.11±1.09 years old). And there was no difference between the frequency distribution of age at menarche and at MPV of BMI. Therefore, the age at MPV of BMI is estimated to be the critical period for body fat mass at the occurrence of menarche. By applying a regression equation (y=1.394x-15.630) of the age at menarche to the age at MPV of BMI, we could estimate the critical period for body fat mass {(10.84±3.58kg)∼(11.53±3.81kg)} at the age of menarche and at MPV of BMI.

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In order to determine optimum time of muscle training for individual rugby players, the authors studied relationship between maturity and specific body surface area (s: body surface area/weight) of rugby players that had played rugby in middle and high school based on longitudinal data for stature growth and body surface area.
The subjects of the study were 74 students of T High School, which won the national championship in 2000 and K High School that won the national championship for three years consecutively in 2002, 2003 and 2004 that were born between the years 1984 and 1986.
Data used for the study consisted of longitudinal stature and weight measured in April each for a period of 12 years from elementary school through high school.
The similar growth curve was observed for growth velocity for longitudinal stature from the standpoint of physiological age based on age at peak height velocity for both average type and early maturity type.
On the other hand, the similar growth curve was observed for specific surface area (1/s) up to age at peak height velocity manifestation for both average type and early maturity type, but subsequent to age at peak height velocity manifestation, the average type exhibited an increase in body surface area (1/s) than the early maturity type. Full-scale muscle training beginning in high school was more suitable for the average type than the early maturity type both qualitatively and quantitatively.

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