In this study, to determine delayed menarche in individual female athletes, the age at maximum peak velocity of BMI and the interval with age at menarche were analyzed. An attempt was made to verify the frequency with which physical stress gives rise to delayed menarche. The subjects were 95 female athletes and 232 girls in their final year of high school. Information including age, age at menarche, and athletic practice was obtained from a questionnaire given to the athletes and control group. Data were also obtained on the girls' longitudinal growth in height and weight from the first year of elementary school (6 years old) to the final year of high school. BMI was calculated from this data, and the wavelet interpolation method was applied for changes in height and BMI with age from 6 to 17 years old. It was found that among female athletes judged to have had delayed menarche the physical stress type of delayed menarche was much more common than fat-related delayed menarche. Therefore, it is speculated that physical stress acts a large role in delayed menarche in athletes.
