WEDNESDAY, Feb. 8 (HealthDay News) -- Intense training combined with insufficient nutrition may threaten the health of young female soccer players, suggests a new study that finds menstrual irregularities and stress fractures are common among these athletes.
Nearly one in five elite female soccer players reported having irregular menstrual cycles, while 14 percent had a stress fracture in the past year, the study found.
Though the toll of so-called "aesthetic sports," such as dance and gymnastics, and endurance sports, such as running, on young women's bodies has been well studied, soccer has largely escaped scrutiny, said lead study author Dr. Heidi Prather, an associate professor and chief of the physical medicine and rehabilitation section at Washington University School of Medicine in St. Louis.
"No one has studied soccer much, yet soccer is the most-played sport by girls in the U.S. as far as sheer numbers," Prather said.
The study, scheduled for presentation Tuesday at the American Academy of Orthopaedic Surgeons' meeting in San Francisco, included 220 elite female soccer athletes from nationally ranked clubs in the St. Louis area, a Division 1 university team and a professional soccer team. Average age was 16.
Nearly one in five of those already menstruating reported irregular menstrual cycles, in which the time between periods was fewer than 28 days or more than 34 days, and/or skipping a period the previous year. They included 19 percent of the 15- to 17-year-olds, 18 percent of college athletes and 20 percent of pros.
"Girls who have menstrual dysfunction are at risk for long-term health problems," Prather said. "When you have menstrual dysfunction and you are not regularly having a period, your body is not receiving the appropriate estrogen load it should."
Too little estrogen can impact bone health, leading to the bone-thinning disease osteoporosis.
Also concerning are the "relatively high and even alarming rate of stress fractures," said Dr. Mininder Kocher, associate director of the division of sports medicine at Children's Hospital Boston.
Stress fractures are tiny cracks in the bone caused by overuse, Kocher explained. The soccer players in the study mostly had fractures of the ankle or foot.
"A bone is alive. When we run and jump, we make small injuries in the bone, but most of the time we're able to heal them. When we're making injuries at a higher rate than we can heal, we get an overuse problem, such as a stress fracture," Kocher explained.
Stress fractures are too small for X-ray detection, but can be seen with an MRI scan. Treatment is typically rest, a healthy diet and adequate consumption of calcium and vitamin D, although some stress fractures require surgery.
The message for female athletes and their coaches is to make sure that in the quest to achieve excellence in sports, they're not compromising their long-term health, Prather said.
Experts call the three major health risks associated with female athletes the "female athlete triad" -- amenorrhea (or absence of periods), disordered eating and osteoporosis.
The good news is that among the soccer players studied, most girls scored in the normal range on a test of eating attitudes, which assesses risk of eating disorders.
Girls who are having irregular periods should bring it up with their doctor, Prather suggested. "And if you've had more than two stress fractures, you definitely should be evaluated to make sure your bone quality is good and you don't have osteoporosis," she said.
Women's bone density peaks at about age 25, so it's important that teens and young women have regular periods and eat a proper diet to maintain their estrogen levels and build bone density to avoid osteoporosis later in life, the experts said.
In another study to be presented at the same meeting, Swedish researchers found that young female soccer players who took part in a 15-minute warm-up were 64 percent less likely to injure their ACL (anterior cruciate ligament), a ligament inside the knee.
The exercises, done twice a week, focused on knee control and core stability. The study involved more than 4,000 female soccer players
Research presented at medical meetings should be considered preliminary until published in a peer-reviewed medical journal.
The Nemours Foundation has more on the female athlete triad.