Hannah Livingston
Amenorrhea is the absence of menstruation. The most common causes of amenorrhea are pregnancy and menopause. However, it can be common for female athletes, which results from reduced secretion of gonadotropin-releasing hormone, which decreases the release of LH and FSH (Tortura & Derrickson). One research study in particular looks at how exercise during puberty may be associated with primary amenorrhea and low mineral density, while exercise after puberty associates with secondary amenorrhea and bone loss. The case study compared 45 prepubertal female gymnasts, 36 retired female gymnasts and 50 controls.
Gymnasts and controls could not participate in the study if they were peri- or postpubertal, if they had anorexia nervosa, or exposure to oral contraceptives, anticonvulsants, or corticosteroids. Controls were excluded if they engaged in more than 6 h of weight-bearing exercise per week. The prepubertal gymnasts were training at an Olympic standard. They trained under supervision for 15-36 hours per week. Most of their training sessions lasted four hours and consisted of a warm up, routine training, and strength and stretching exercises (Journal of Bone and Mineral Research).
In the cross-sectional analyses, areal bone mineral density and primary amenorrhea in active prepubertal gymnasts was higher at the weight-bearing sites than the predicted average in the control group. The Z scores increased as the duration of training increased. During 12 months, the increase in areal bone mineral density and amenorrhea in the active prepubertal gymnasts was 30-85% greater than in controls. In retired gymnasts, areal bone mineral density and amenorrhea was higher as well, resulting in a correlation between intense athletic training and higher bone mineral density as well as amenorrhea (Journal of Bone and Mineral Research).
Gerard J. Tortora and Bryan Derrickson. Principles of Anatomy and Physiology. 13th ed., John Wiley and Sons, 2012.
Journal of Bone and Mineral Research. Exercise Before Puberty May Confer Residual Benefits in Bone Density in Adulthood. S. Bass G. Pearce. 2013.