Influence of high intensity training on menstrual cycle disorders in athletes.

AIM: To estimate the influence of intensive training on menstrual cycles in female athletes.
METHOD: The questionnaire was used to determine the time of menarche, and the prevalence of primary and secondary amenorrhea and dysmenorrhea in 72 active female athletes from Zagreb (10 volleyball players, 18 basketball players, 10 ballet dancers, and 34 runners) aged between 15 and 21. The control group comprised 96 girls of the same age not engaged in any sports activity.
RESULTS: The prevalence of secondary amenorrhea was three times higher in athletes than in the control group (p=0.037). The prevalence of primary amenorrhea was substantially higher in athletes than in the control group (6/72 vs. 0/96, p=0.014), whereas the prevalence of dysmenorrhea was twofold lower in athletes than in the control group (p<0.001). The highest prevalence of secondary amenorrhea was recorded in runners (14/31), particularly long-distance runners (11/17), whereas there was only one case of secondary amenorrhea among basketball players. Menarche was significantly delayed in the athletes who started physical activities before the onset of menstruation (13.8+1.4 vs. 12.6+1.0 years, p<0.001).
CONCLUSION: High-intensity training before menarche postpones its onset. Type of training may be related to a significantly higher prevalence of secondary amenorrhea in runners than in basketball players.