Progressive nature of menstrual disturbances. Usually stages 1-3 are asymptomatic but may present as infertility. One out of four moderate and long distance runners demonstrated one or more episode of anovulation when observed for one year. Most frequently seen in ballet dancers and long distance runners. However, menses will resume in amenorrheic ballet dancers after injury in the absence of any significant change in weight or body fat.
Amenorrhea returns when their training resumes.
Studies have found decreased caloric intake and a lower metabolic rate in amenorrheic athletes compared to those with normal menses. However, some have postulate that the lower resting metabolic rate is just the body's adaptive response in attempt to maintain weight and conserve energy thereby restoring a more normal energy balance. These conditions have been associated with amenorrhea. In these patients nutritional and psychological factors must be considered. It has also been noted to be chronically elevated at rest in competitive swimmers who have trained for two or more years.