News from Delco Road Running Club

Consider the results of a series of experiments published last month involving female rowers in Europe. Some of the women were competitive athletes, others hobbyists. Some were using oral contraceptives, which lower production of the body's own estrogen while maintaining consistent levels of a synthetic variety; others were not. All of the women came into the lab multiple times throughout the month, including on days when their estrogen levels were at their peak and ebb, to complete a fitness test on a computerized rowing machine. Each time, their heart rates, oxygen consumption, power output, blood lactate levels and other measures of endurance, strength and general fitness were measured.

Those measurements, as it turned out, never varied, no matter where a woman was in her menstrual cycle. She could row just as long and powerfully whether her estrogen levels were high, low or in between; whether she used contraceptives; and whether she was an experienced, competitive athlete or a rowing duffer.

These findings are important, because many people, including coaches and athletes, have long contended that women's endurance and overall performance may flag at certain times during the month - although there is disagreement about when those times are. And many female athletes have been told, or have chosen, to start or discontinue using birth control pills to manipulate their hormone levels.

But "endurance performance was not influenced by the phase of the normal menstrual cycle" or "the synthetic menstrual cycle" of those on oral contraceptives, the authors of these new studies write. Consequently, women "should not be concerned about the timing of the menstrual cycle with regard to optimized, sport-specific endurance performance."

There may, however, still be reasons a woman to consider her period when planning training. A study published this year by scientists at the University of Melbourne in Australia, for instance, found that when women's estrogen levels were at their highest, around the time of ovulation, they landed subtly differently while hopping than at other times of the month. Their feet splayed, the arch collapsing just a little bit more than it did when their estrogen levels were lower. The women also seemed, to a small degree, wobblier. "We contend that the changes in foot biomechanics may be due to the effects of estrogen on soft tissue and/or the brain," said Adam Leigh Bryant, a senior lecturer at the University of Melbourne and lead author of the study.

But whether such small bodily changes actually affect injury risk is not clear. Other researchers have examined injury patterns in female athletes and found little consistent evidence that injuries, including the dreaded A.C.L. tear in the knee, are more common at any particular point during the menstrual cycle.

Still, said Dr. Bryant, active women probably "should be careful during the ovulatory phase of their menstrual cycles," particularly if they play sports that involve hopping, landing and cutting, like soccer, basketball and, for those of us who are regrettably clumsy at striding off of curbs, jogging.

None of which, though, should suggest that female athletes are in some indefinable way more fragile than their male counterparts. Quite the reverse may in fact be true, according to some reverberant new research into athleticism and the menstrual cycle. In a series of experiments at the University of Denmark, scientists found that during exercise training, women's tendons and ligaments didn't grow as thick and powerful as men's did, which had been expected. But after they reduced or stopped their workouts, women did not, in subsequent studies, lose their training benefits as quickly as men did.

Estrogen, the researchers concluded, had maintained the women's hard-won strength and fitness gains better than men's bodies had held on to theirs, for a simple evolutionary reason. It was protecting the women "against fast muscle and collagen loss when she is inactive," as during pregnancy, the study's lead author, Mette Hansen, a researcher at the Institute of Sports Medicine in Copenhagen, told me in an e-mail. Estrogen makes women stronger in adverse conditions, Dr. Hansen concluded, a lesson that the fine, battle-hardened United States women's soccer team can take solace in going forward.

Editor's Note: Really? I should probably just stop now. If you are familiar with Tosh.O, then lets put 20 seconds on the clock. Insert jokes here.