Fit For You: Men vs. Women in Endurance Sports

Jul 12, 2017

The battle of the sexes has been long documented - especially in sports. Women have made tremendous strides in both novice and professional competitions, but the question of attaining a truly even playing field remains uncertain.

When it comes to sports performance, things are not equal. Men are generally stronger and faster than women thanks to their physiology. However there have been claims made over the years that the longer an event goes -- think ultra-marathon or even longer -- the more advantages women have over men.

Women have broken through to either win or set records in major endurance competitions such as ultramarathons, World's Toughest Mudder, and the Trans Am. But are these victories exceptions rather than the rule? Dr. Sandra Hunter of Marquette University's Exercise Science Program has been studying the sex differences in sports for more more than two decades - long enough to compile a great deal of data.

She states that overall, in most sports that require power or some type on endurance, the best men will always outperform the best women. There is overlap where a lot of women can perform better than men, says Hunter, but "in terms of endurance, the maximal oxygen consumption - that capacity for men is better due to larger hearts, bigger muscle mass, more hemoglobin, and less body fat to carry."

If women aren't competing at the same rates and the participation is less, we really won't and don't understand the true physiological sex differences and what's relevant for women.

Hunter notes that there is about a 10-12% difference in world records between men and women across the board. "That's just the bottom line, and it's always going to make it difficult for women to outdo men." 

Her research shows that while men may succeed more in endurance sports, women are less fatigue-able than men if you get them to perform a very particular exercise at the same intensity as a man. Women's arms and lower limb muscles consistently outperform men's due to the different makeup of muscle fibers. "Women on average have more fatigue resistant muscle fibers then men," says Hunter.

There are two approaches to understanding the sex difference, according to Hunter: one is to bring men and women into the research laboratory to research physiology, and the other approach is to take real-world performance data and try to understand physiology based on that data.

The latter method of research is not as accurate because the records of women's performances in sporting events have not been compiled as long as men's. Hunter notes that women could not officially compete in marathons until the 1970s, therefore the amount of records compiled is clearly not equal.

"The reality is you get less women and less men competing in those [endurance] events, so you get more of these anomalies that occur," notes Hunter.

She also states that women are not studied or included in research as often as men. This not only has big implications for sports research, but for medical research as well. Hunter says that some male researchers she has met express their reluctance to study women because they are uncomfortable in dealing with menstrual cycles. She says the menstrual cycle in fact has very little impact on a woman's performance.

"The differences across the menstrual cycle for a woman...are much less than the differences between men and women," Hunter explains. "They're just small fluctuations and they really have very limited effect on some of the more pertinent issues of strength and fatigue-ability. So I think it's more perception and that we just have got to start including women more than men in a lot of these studies."

Another claim Hunter has proven wrong is the notion that men are more competitive than women. "We do studies in my lab where we actually measure the ability of the brain to activate the muscle, and there's zip differences between men in women. That in fact women are equally motivated to perform maximal contractions just as much as men are," says Hunter. She notes that women try just as hard as men, but women also historically have had fewer opportunities to participate in exercise and some sports events such as the marathon. Hunter adds that women in general tend to participate less in exercise than men, although it's not clear why. It could be attributed to the myriad of other responsibilities and priorities that men may not share in their daily lives.

It's not like women are less than men or men are less than women. I talk about this not because I think women are more important, but because they're just as important.

Just as motivation doesn't differ between the sexes, nor does the age at which men and women peak in performance. According to Hunter, the average age of peak performance is 29 for both men and women. She came upon this discovery after a Runners World journalist asked her about age and performance after the 2008 Beijing Olympics - the woman who won the marathon was 38 years old while the man was only 21 years old.

Hunter says the real issue is not about definitively proving which sex is "better" through physiological tests.  The bottom line is "if women aren't competing at the same rates and the participation is less, we really won't and don't understand the true physiological sex differences and what's relevant for women."

Only time will tell whether the sex difference can be measured appropriately once men and women are equally incorporated in competitive sports. "Then we'll really see what those differences are," says Hunter. "And those differences should be celebrated. It's not like women are less than men or men are less than women. I talk about this not because I think women are more important, but because they're just as important. And I think that is a really key thing to remember."