[This article originally appeared in the
August 2001
issue of Northwest Runner
magazine.]
Some people may think it rather obvious that, on average, men have an advantage over women when it comes to distance running. However, a 1992 analysis of track and field records (Whipp & Ward, Nature 355: 25, 1992) suggested the possibility that the fastest women in the world might catch up to the fastest men in the not-too-distant future. Such a scenario would imply that women have the same athletic potential as men. So, is that really true? Or, alternatively, do men have certain biological advantages that they are unlikely to relinquish within the next century?
I'm not going to attempt a comparison of male and female sprinters. For distance runners, however, we can compare men and women using the endurance performance model described in my February column. You may recall that the model includes three components -- maximal oxygen consumption (VO2max), the lactate threshold, and running economy -- each of which is considered an important determinant of success in races ranging from 3 to 30 miles.
Although the gender difference in VO2max is well-documented, a mystery remains (Joyner, Exercise and Sport Sciences Reviews 21: 103-33, 1993). Some champion male distance runners (past examples include Derek Clayton and Frank Shorter) have VO2maxes of "only" 70 ml/kg/min, a value occasionally exceeded by elite women, yet no woman has ever matched their race times. Why not? Again, a firm answer is not forthcoming at present. However, it is possible that "an excellent value for one of the limiting factors [V02max, lactate threshold, and running economy] is mutually exclusive with another," Joyner speculates. If this is the case, "It might be more likely for some of the males with VO2max values in the low range for [elite] men to have outstanding running economy and lactate threshold values and, therefore, faster times in competition than a female competitor with the same VO2max."
Ladies first
The above analysis is most relevant to race distances of roughly 3 to 30 miles. When considering events toward the upper end of this range and beyond, however, some biological factors that favor women may also come into play. First, women should tolerate hot and humid racing conditions better than men due to their smaller body size (Dennis & Noakes, European Journal of Applied Physiology 79: 280-4, 1999; Marino et al., Pflugers Archiv 441: 359-67, 2000). The issue here is whether heat can be removed from the body as quickly as it is produced. The rate of heat removal depends on the body's surface area (how much skin you have, more or less), while heat production is approximately proportional to the body's volume or weight. People with a high ratio of surface area to volume are therefore better able to get rid of the heat they generate. Because of the way in which various bodily dimensions scale relative to one other, it turns out that small people have higher surface-area-to-volume ratios than large people; therefore, women may be less susceptible than men to overheating during a long race in oppressive weather.
The information presented in the previous two paragraphs leads to the prediction that women might compete against men most successfully in events lasting several hours, where overheating and glycogen depletion are particularly common. The limited data we have so far provide preliminary support for this idea. It has been shown that women can sometimes finish ultramarathons in times similar to those of men who can beat them in "short" (26.2-mile) marathons (Bam et al., Medicine and Science in Sports and Exercise 29: 244-7, 1997). And when men and women with equivalent marathon times are pitted against each other in ultras, the women tend to win (Speechly et al., Medicine and Science in Sports and Exercise 28: 359-65, 1996).