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

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).

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.

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.

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.