March 3, 2016

Women appear to be closing the gap in endurance running, but are they faster than men?

Women's improved performance in long-distance races may be in the muscles, researchers find
Faculty of Kinesiology researcher Guillaume Millet (right) and postdoc fellow Dr John Temesi have been studying whether physiological differences give women an edge in long-distance races.
Faculty of Kinesiology researcher Guillaume Millet (right) and postdoc fellow Dr John Temesi have be Riley Brandt, University of Calgary

Katherine Switzer was the first woman to run the Boston Marathon in 1967. It was a scandal. Decades later, many women compete and it’s not uncommon for them to beat their male competitors in the longest and most arduous conditions.

Leanne Yohemas spoke with Faculty of Kinesiology researcher Guillaume Millet, also an ultra-endurance runner, to find out if women have what it takes to better or equal their male competitors. His research was published in Medicine and Science in Sports and Exercise and was highlighted in the American College of Sports Medicine Bulletin.

Q: Let’s get our terminology straight. What is considered ultra endurance?

A: In running, a simple answer to that question would be any distance above the marathon (which is 42.195 metres). However, distance is probably not a good criteria. Fifty kilometers for an elite ultra-endurance runner will be easy while it is clearly a real ultra-distance for a novice. Thus it is probably better to consider that ultra-endurance is above five-six hours. The good thing about considering duration rather than distance is that it also allows to include sports other than running. Ironman triathlons or the Race Across America in cycling are famous examples of ultra-endurance events.

Q: When did women start running long distances competitively?

A: Not much later after they started participating in marathons. For instance, the famous Comrades ultramarathon (90 km) in South Africa, created in 1921, was officially open in 1975 to women competitors. Interestingly, this same year it was also the first time the race was open to runners of all race groups. The history of ultra-trail running is more recent but women almost immediately took part in the events. This was also in the mid-'70s.

Q: What does your research show when you compare male and female runners at certain distances?

A: It is very clear when we examine the participation that the longer the distance, the lower the percentage of women on the start line. With my postdoc fellow Dr. John Temesi, we tried to understand if physiology played a role in it. To do this we evaluated fatigue of 10 male and 10 female ultra-trail runners before and after they completed a 110-km ultra-trail running race with almost 6,000 metres in positive and negative elevation change. The subjects were matched by finishing time calculated as a percentage of the winning time of their sex. We found that the magnitude of fatigue within the central nervous system and brain was similar for both sexes. However, we measured a greater fatigue in the quadriceps and in the calves for males, suggesting that differential fatigue between the sexes occurs at the muscle level. These differences may partly explain the reports of great performance by females in extremely long duration running races.

It is not uncommon for female runners to beat their male competitors in the longest and most arduous conditions.

Female runners often beat their male competitors in the longest and most arduous conditions.

Q: Is this the only factor that makes women equipped to potentially outpace men?

A: Women have bettered men in many endurance events. One high-profile example is Pam Reed, who was the first woman to become the overall winner of the 212-km Badwater ultramarathon that takes place in Death Valley, California. She did that twice. In addition to our research on greater muscle fatigue resistance, previous studies have shown that women might have a slightly better running economy, a better ability to resist tissue damage and a higher capacity to use fat as energy store, which allows to spare glycogen, the limiting substrate.

Q: So if women can outpace men, why do they still comprise a low proportion of the entries, sometimes less than 15 per cent?

A: I am an exercise physiologist, not a sport sociologist but yes I believe the reasons explaining the very low proportion of the entries are mainly socio-cultural. At least at a certain age range, between 20 and 50 years old, it is probably just related to the fact that women have less time to train. Yet, a very important difference between sexes is that men have a higher maximal oxygen uptake due to an elevated hemoglobin concentration. For this reason, women, on average, will most probably never outpace men in endurance or ultra–endurance sports.

Q: Does injury play a part? Are women more injury-prone than men?

A: The few data published on that topic in ultra-endurance runners suggest that there is no difference among sexes in exercise-related injury during training or in the number of medical consultations during ultra-marathons. One study actually suggested that women tended to consult doctors less during the races. The only difference might be that being a woman could be associated with greater risk of a stress fracture but this injury affects only five per cent of all runners.

Q: How does your study of gender differences in endurance inform other parts of your research?

A: Generally speaking, our work with athletes mainly helps us to develop and test new methods to assess fatigue, methods that we can then use with patients. Yet, although a female ultra-endurance runner obviously differs compared to, for instance, a breast cancer survivor, our research allowed us to better understand the women’s specific response to exercise.