Thesis research done by Rachel C. Snow, another member of the team who is doing post-doctoral work at the SPH, has also served as important background information for the current NIH analysis.

Snow, who also works at the Center for Population Studies, has researched estrogen metabolism in female athletes, basing most of her conclusions on a study of 10 "elite oarswomen" and the way their bodies process the female hormone involved in developing secondary sex characteristics.

She found that those athletes with menstrual dysfunction while in high-intensity athletic training metabolized a greater fraction of their estrogen to "non-potent" forms, to which the reproductive organs will not respond. The increase in non-potent estrogen production also means that there is less normal hormone circulating in the blood, and this may lead to a lower risk of estrogen-dependent tumor development, such as breast cancer, Snow says.

However, Snow, a former member of the national lightweight rowing team, found that not all women who exercise metabolize their estrogen in this way. Those women who do have the metabolic abnormality also have menstrual dysfunctions, are leaner and do not ovulate.

Snow says she hopes the current NIH-funded oarswoman study will help the team to "understand this individual variability."

Current Study

The current research project centers around four sets of tests under the direction of a pair of physicians at the Brigham and Women's Hospital and the Massachusetts General Hospital (MGH). Three of the procedures measure body fat, and the other traces estrogen metabolism in the body.

One of the tests, which uses Magnetic Resonance Imaging (MRI) techniques, helps give doctors an accurate picture of where subjects' body fat is located and how it is stored, without any of the harmful radiation effects of X-rays, according to MRI experts.

The MRI procedure, supervised by Bruce R. Rosen, an assistant professor at the Medical School and the director of Clinical Nuclear Magnetic Resonance at MGH, serves as the main emphasis of the entire project, entitled, "MRI--of body fat, ovulation, and estrogen metabolism."

Another of the project's tests follows the breakdown of estrogen by allowing doctors to trace low levels of radioactive forms of the hormone molecules through the body. "Athletes destroy estrogen faster than non-athletes, so their bodies are exposed to less" of the hormone, and this may lead to decreased cancer risk, says Barbieri, who has worked with both Frisch and Snow in the past.

"Hopefully, we will be able to understand how estrogen metabolism and fatness work in individual women, and to explain the frequency of ovulation," Snow says of the project.