[Delayed menarche following early onset of athletic sports training]

To investigate the effect of athletic sports training on the onset of menarche, we submitted questionnaires to college students at University of Tsukuba. 311 students (174 college athletes and 137 non-athlete control students (group C) completed the questionnaires. The college athletes were divided into hard physical activity (group A) and moderate physical activity (group B) groups. The average age was similar in each group. The physical profile showed that group A and B were significantly (p less than 0.001) taller and heavier than those of group C. There was no significant difference among the average menarcheal age of group A (12.9 +/- 1.1 years, Mean +/- S.D.), group B (12.8 +/- 1.1 years) and group C (12.6 +/- 1.0 years). However, some of athletes in group A who had begun sports training before menarche had a later menarcheal age (13.1 +/- 1.1 years, p less than 0.001), and others who had begun training after menarche had a significantly earlier menarcheal age (12.1 +/- 0.9 years, p less than 0.001) whereas in group B the average menarcheal ages of premenarche-trained (12.9 +/- 1.1 years) and postmenarcheal-trained (12.3 +/- 1.1 years) students were similar to that of group C. These data indicate that early beginning of hard athletic training delays the onset of menarche.