University of Iowa Health Science Relations and
Ginny Ryan, MD
Fellow in Reproductive Endocrinology and Infertility
First Published: 2004
Last Revised: December 2004
Peer Review Status: Internally Peer Reviewed
It is not uncommon for athletes to suffer such ailments as stress fractures, runner's knee, bunions and blisters. But female athletes face the additional problem of amenorrhea--loss of menstrual periods, says a University of Iowa endocrinology specialist.
"It is not unusual for women engaged in heavy exercise or competitive sports to have amenorrhea," says Dr. Ginny Ryan MD, a fellow in reproductive endocrinology at the University of Iowa Hospitals and Clinics. "Amenorrhea can be triggered by weight loss, disordered eating and stress, all of which are common among women athletes."
Research indicates that athletes who participate in endurance sports, such as swimming and running, and aesthetic sports, such as gymnastics and ballet, have a higher incidence of amenorrhea. But athletes with amenorrhea have been reported in all sports, including competitive power lifting, Dr. Ryan says.
The number of women engaged in competitive sports has increased dramatically in the last few decades, and their training programs have more intensity and volume than ever before. In addition, a particular body shape is often expected in a given sport for performance or aesthetic reasons, according to Dr. Ryan.
The result is that many of these athletes are chronically energy deficient. "This means that the fuel they take in does not have enough calories or nutrients to meet their body's needs. Energy deficiency can lead to problems with athletic performance, growth, and health including reproductive health," she says.
Amenorrhea results when the brain receives signals saying the body is in an energy deficient state. The brain then temporarily slows down or shuts off the reproductive axis, leading to fertility problems and irregular or absent periods. "When the reproductive axis is on hold like this, there is also a decrease in estrogen production. This can lead to reduced bone growth and osteoporosis," Dr. Ryan says.
Surprisingly, psychological stress seems to have little effect on the development of amenorrhea in athletic women, Dr. Ryan notes. Studies show there are no measurable differences in psychological stress tests between high-intensity athletes with regular cycles and those with amenorrhea.
However, medical studies have shown that physical stress plays a role in the development of amenorrhea, she says. "The athlete who runs or swims longer, more often, and with more intensity, is more likely to develop amenorrhea."
Studies show that in women who run 10-20 miles a week, only 10-15 percent have amenorrhea. But when the mileage is increased to 60 miles a week, 20-30 percent of the athletes suffer amenorrhea. Dr. Ryan adds that in women weighing 125-130 pounds, not many have amenorrhea, but in those weighing about 102 pounds, 60 percent are amenorrheic. "This shows the combined training intensity and energy balance," she notes.
If women athletes have skipped their monthly menstrual periods, they should consult a physician. A physical exam and laboratory evaluation are recommended to confirm a suspected diagnosis of amenorrhea and rule out other causes of amenorrhea.
One of the treatment options for amenorrhea in women athletes includes weight gain and a reduction in physical training. "But since these suggestions tend to be unrealistic for most competitive athletes, physicians must determine if the amenorrheic condition or 'low estrogen state' is causing them harm," Dr. Ryan says. Reproductive function may improve with small improvements in diet and minimal change in exercise regimen.
Preliminary research has suggested that these patients have decreased bone mass, also known as osteoporosis. This condition can lead to stress fractures. Estrogen replacement therapy may be recommended for some patients, Dr. Ryan notes. Often in the form of oral contraceptive pills.
Women athletes who have amenorrhea and wish to become pregnant may require fertility drugs to induce ovulation. However, amenorrhea should not be considered a form of contraception, Dr. Ryan warns. Women with amenorrhea may ovulate at any time.