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An Everlasting Gender Gap?

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Science  30 Jul 2004:
Vol. 305, Issue 5684, pp. 639-640
DOI: 10.1126/science.305.5684.639

For a while, female runners were closing in on their male counterparts. Now they're barely keeping the guys' taillights in sight

When the U.K.'s Paula Radcliffe ran the London Marathon last year in just under 135 minutes, shaving almost 2 minutes off the record she set in 2002, the whispers started again: Are women improving their performance so quickly that one day they may compete on the same tracks with men?

Expert opinion suggests that day will remain elusive—as long as women retain female bodies. The gap between the sexes appears to have plateaued, with women performing at about 90% of male levels. Apart from the marathon, “world records for women have been absolutely static” for more than a decade, notes Kenya-born journalist and running expert John Manners.

That plateau wasn't evident 12 years ago. In a letter to Nature published on 2 January 1992, titled, provocatively, “Will women soon outrun men?,” Brian L. Whipp and Susan Ward of the University of California, Los Angeles, looked at the world records of five standard Olympic running events, from the 200-meter dash to the 26-mile (42-kilometer) marathon, from the 1920s through 1990. They found that women were improving their times at double the rate of men in the short distances and were narrowing the gap even faster in the marathon, in which record-keeping for women only started in 1955. “The gap is progressively closing,” the authors wrote. At that rate, they projected that marathon times could converge by 1998 and that gender differences in all races could disappear by 2050. In 1996, a poll by U.S. News and World Report reported that two-thirds of Americans believed that “the day is coming when top female athletes will beat top males.”

Absent unforeseen genetic or hormonal interventions, men, it seems, will maintain an advantage. That's due largely to their steady supply of a performance drug that will never be banned: endogenous testosterone, which boosts muscle power and oxygen capacity. The typical young man has a maximum oxygen use capacity, or VO2 max, of about 3.5 liters per minute, compared with 2 liters for a woman, says physiologist Stephen Seiler of the Institute of Health and Sport at Agder College in Kristiansand, Norway. Although individual levels of testosterone vary widely, males tend to have at least 10 times as much of the stuff as women. The hormone stimulates the creation of red blood cells, which means that men's blood holds about 10% more of the oxygen-carrying protein hemoglobin. But oxygen is not the whole story. Kirk Cureton of the University of Georgia School of Health and Human Performance in Athens compared the performance of male and female athletes on an exercise bicycle after scientists had withdrawn blood, leaving the subjects with equal amounts of hemoglobin in circulation. That reduced but did not eliminate the sex difference in VO2 max, indicating that other factors, particularly musculature, play into the difference.

Fall of eastern superwomen.

Drug use helped inflate female performance before the fall of communism.

CREDIT: ADAPTED FROM S. SEILER

Men have more muscle and larger hearts in relation to body size, says Dirk Christensen, an exercise physiologist at the University of Copenhagen. This affects aerobic capacity: He says that a trained woman's heart can pump out the same volume of blood as a man's can, but it has to work much harder to do so.

Because testosterone spurs growth of muscle tissue, it also affects anaerobic capacity—the ability to produce energy quickly without oxygen—which gives males an edge in sprinting as well. The primary energy for the intense bursts of power required for sprints is generated anaerobically, explains retired Michigan State University anthropologist and sports expert Robert Malina. Indeed, after launching themselves for a 10-second sprint, some athletes “don't take another breath till it's all over,” he says. (Endurance running in contrast relies almost exclusively on aerobic energy.) More muscle means more of the two main anaerobic energy sources: phosphocreatine and glucose.

Recent records support the gender-gap plateau, Seiler says. A few years ago, he and writer Steve Sailor analyzed results from Olympic games and world championships of the International Association of Athletics Federations between 1952 and 1996, selecting events in which men and women ran under the same conditions. They found that if the marathon —which wasn't an Olympic event for women until 1984—were excluded, the mean performance gap for running events increased from 11% in the mid-'80s to 12% in the mid-'90s. They also observed that men's world records were broken far more often in the '90s than women's—largely due to the extraordinary performance of East African runners (see p. 637).

Seiler recently updated these numbers for Science. He reports that from the world records in the eight main running events from 100 meters to the marathon, seven suggest an increasing gender gap. The marathon is the exception: The gap has narrowed from 11.9% to 8.4%, thanks to Radcliffe's new record. Seiler says the current average gap is now 11.01%, up from 10.4% in 1989. In short, he says, “at the highest levels of performance, the gender gap in running performance has actually widened over the last 20 years.”

Much of the female record is clouded by drug use, especially the records set in the 1970s and '80s by Eastern European women that have never been bested. In 1984, 38 women, mostly from the East Bloc, ran 1500 meters in under 4.05 minutes, according to Jon Entine in his book Taboo. In 1991, only nine did.

Although the impressive gains in female marathon performance have suggested to some observers that women have greater endurance than men, physiologist Henrik Larsen of the Copenhagen Muscle Research Centre says that's not so: “Women had not developed long distance; that's why the improvement is much greater on the marathon. We don't see any higher oxidative capacity in women.” Exercise physiologist Timothy Noakes of the University of Cape Town, South Africa, agrees. A smaller body frame gives women an edge on endurance, he says, but men can run 10% faster even when the difference in body size is controlled for.

Runaway record holder.

Paula Radcliffe keeps carving minutes off the marathon.

CREDIT: STU FORSTER/GETTY IMAGES

Whipp says he's still keeping an open mind on the subject of male-female competition. He told Science that he and colleagues are currently working to extend their analysis of world running records to 2003. His team has looked for “a pattern of response that would suggest a physiological limit,” he says, but so far has found none. “There is no evidence at the beginning of the 21st century that the human athlete has reached the limit of [his or her] potential,” Whipp says.

But that appears to be a minority view. “We are approaching the limits of human performance in a lot of the one-dimensional events like the 100-meter sprint or marathon,” says Seiler. “Records will continue to be broken, but the price is extremely high. And the percentage of the population that has the genetic potential to excel at this level is infinitesimal.” As for the gender gap in running, he defers to Norway's marathon queen Grete Waitz, setter of world records in the 1970s and '80s, who said: “As long as women are women, I don't think they will surpass men.”

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