What Makes Women Strong?
By: Starre Julia Vartan
Tags: Gender, Strength, Body, Equality, Sports

One of the biggest challenges impacting women’s ability to compete is the lack of scientific information when it comes to female bodies and exercise. Women weren’t regularly included in exercise physiology and biomedicine studies until 1993, when President Clinton passed a bill that required that women be included in all National Institutes of Health (NIH)-funded Phase 3 trials (although a 2007 analysis showed that many researchers still weren’t meeting the requirement.) In 2014 the NIH updated its rules to mandate that female mice had to be included in animal studies, but a recent review shows that test subjects are still only about 20% female.

There are many excuses for the lack of gender parity in research, says Stacy Sims, a senior research scientist in exercise physiology at the University of Waikato in New Zealand. “I’ve heard things like, ‘We don’t know enough about men; why do we want to study women?’ Or it’s that ‘women are too different’ or ‘there’s not enough funding,’” says Sims. Menstrual cycles are often blamed for making results too complex but Hunter calls that excuse “rubbish.” The fact is that many variables are compensated for in exercise physiology studies: “There’s other characteristics such as stress, prior physical activity, or nutrition which we don’t blink about controlling for,” says Hunter.

“In humans, men, but not women, self-reported higher levels of stress when tested in a room previously associated with tonic [chronic] pain.”

Despite this limited research, what scientists are learning about women’s bodies — and strength in general — is compelling. It also is leading them to question how strength is defined.

Strength is often characterized by an ability to withstand pain — like continuing a race even through intense discomfort. Studies disagree on whether women feel pain more or less severely than men since there is a strong cultural element to reporting one’s own pain perception. Regardless, data shows that women appear to be less stressed by pain. A recent study of both mice and humans found males were more sensitized to pain, and remembered it more clearly: “In humans, men, but not women, self-reported higher levels of stress when tested in a room previously associated with tonic [chronic] pain,” the researchers wrote. This may give women an advantage. Take, for example, the 2018 Boston Marathon. The day of the race it poured rain and temperatures were freezing. But a look at the final figures showed that women were substantially more likely to finish the race than men. The dropout rate for the race was up almost 80% for men from 2017, but among women it was up only about 12%. It was a trend that was present even among elite runners, the New York Times reported.

If discussions of human physical strength used endurance as the yardstick, women would be strongest. Women have already caught up to, or surpassed, men in some sports like long-distance swimming and ultrarunning, racking up the wins in mixed-gender races (with less support and training than the men). Recently, Camille Herron won 2018’s Desert Solstice run, which lasts for 24 hours (she ran 162.9 miles in that time) and Courtney Dauwalter has won 11 mixed-sex ultramarathons, including the Moab 240, a 238-mile race along the Colorado River in Utah. Dauwalter beat the next-fastest competitor there, a man, by 10 hours.

In fact, plenty of research points to the idea that the longer the distance, the better chance a woman has in beating a man, possibly due to a combination of factors like high pain tolerance and less muscle fatigability. There could also be metabolic reasons — some researchers theorize that women burn energy in a way that supports long-distance energy needs. As investigative reporter David Epstein notes in his book, The Sports Gene, when a man and a woman are evenly matched, “the man will typically beat the woman at distances shorter than the marathon, but the woman will win if the race length is extended to forty miles.”

It’s not just on foot that women have endurance advantages: In the 28.5-mile Catalina Channel swim, considered part of the “Triple Crown of Open Water Swimming,” the fastest woman was 22 minutes faster than the quickest guy, and overall, according to an analysis, “the annual fastest women crossed the Catalina Channel faster than the annual fastest men.” Diana Nyad is the first and only person who swam the 110 miles from Cuba to Florida — and she did it without a shark cage for protection.

Hormones may also give women an edge in endurance sports. Testosterone — which is important for the health of both sexes — has long been offered as the reason men can build bigger muscles. But estrogen (which is produced mainly by the ovaries, but also by fat tissue) may regulate how nutrients are used when the body is under physical stress: “Estrogen may promote endurance performance by altering carbohydrate, fat and protein metabolism,” writes Mia Schaumberg, a researcher at the University of Queensland in Australia, in a 2017 study. And because women tend to carry more body fat than men, they may be able to utilize those stores in longer-distance races.

Women’s muscles also tire less easily, which is something Hunter, the professor of exercise physiology at Marquette, has been researching since the beginning of her career. As a postdoc, she first got interested in the idea when she was doing a simple test looking at how long people could push with their hands against a weighted mechanism — the major muscle tested was the bicep. Hunter tested herself and could go for 20 to 30 minutes at a time, but the “big burly guys” who came into her research lab could often push for less than 10 minutes. When she tested a wide sample of people, she found that overall, women could push for twice as long as men at weights that were 20% of the maximum weight each person could push.

Hunter hadn’t expected such a difference in results. “Nobody had really looked at this. It became a profound study,” she says. Hunter has continued to study this phenomenon. “On the whole, women have a muscle fiber makeup that’s able to lift less [than men], but women have the ability to drive their muscles harder,” says Hunter. She’s now delving into the metabolic reasons for this difference, but women’s muscles getting less tired over long-distance pursuits is one good reason for endurance ability.

Women are also bodily powerful (the definition of strong) in other ways: Women are also more flexible. “Women tend to have somewhat more laxity in their tendons than men; they are more limber,” Dr. Steve Jordan, an orthopedic surgeon at the Andrews Institute for Orthopaedics and Sports Medicine, told the New York Times. Limber people are less likely to get hurt — less time spent on the sidelines or in surgery. Woman also have a very high degree of accuracy — and depending on the physical pursuit, that can make one athlete stronger than the next. Women on the Ladies Professional Golf Association tour regularly significantly outdrive professional men. And according to the National Rifle Association’s Colonel Kenneth Haynes — a military logician in the Army who taught both men and women to shoot over a multi-decade career — women shoot guns more accurately: “My units had around 20 percent female personnel in both officer and enlisted ranks. All the women fired Expert their first day, but less than a third of the men did so,” writes Haynes.