An approach to verifying delayed menarche in Japanese female athletes. Analysis by wavelet interpolation method

AIM: The theory of delayed menarche in female athletes, despite some evidence for such a delay, has not yet been verified. We examined a means to verify this hypothesis by comparing ages at menarche and at peak height velocity (PHV) derived from the wavelet interpolation method (WIM) for female athletes and non-athletes (control group). METHODS: We identified age at maximum peak velocity as the index of the physical maturation rate by WIM. We then conducted a study involving 144 female athletes in their 1st year at University in the Tokai area, all of whom had competed in a national high school sports competition (athlete group). Past school records of these subjects' heights from the 1st grade of elementary to the 3rd year of senior high school (1984-1995) were collected, and ages at menarche were ascertained from questionnaires. A control group of 78 non-athletes was similarly examined. RESULTS: This difference (interval) between age at menarche and age at PHV was 1.62 years (SD=1.25) in the athlete group and 1.08 years (SD=0.74) in the control group. The difference between the 2 groups was statistically significant (P<0.01). This finding provides evidence that menarche in female athletes is delayed in relation to physical maturation rate. CONCLUSIONS: This result alone cannot establish whether athletic training is the only cause of this delay; however, an approach to verifying the hypothesis of delayed menarche in female athletes has been established by this finding.