Found on RunnersWorld.com and written by Scott Douglas
If, at the start of your next marathon, a man and a woman both tell you they’re aiming for the same time, count on the woman, suggests a study published in the Journal of Strength & Conditioning Research.
Researchers looked at how well runners who broke 5:00 in the 2007 and 2009 Chicago Marathons paced themselves, as judged by the consistency of their 5-kilometer splits. In line with previous studies (not to mention anecdotal observations), elite runners in the races did a much better job than non-elites of maintaining a relatively even pace throughout the race.
When the researchers considered only the non-elites, they found that, at both editions of the marathon, women slowed less than men, especially between 30K and 40K of the 42.2-kilometer race. (On average, both genders picked up the pace a little for the final 2.2 kilometers of the marathon.) This was true among all age groups and subsections of finishing times.
Marathon historians will note that the two years studied featured notable race-day weather. In 2007, the average temperature was 80 degrees Fahrenheit. In 2009, the average temperature was 37 degrees Fahrenheit. In the hot year, non-elite men were especially bad at pacing themselves. Although, on average, men in the hot year started out at a little over 8:20 per mile, by 35K they had slowed to a bit over 10:00 per mile. The average woman that year started at just under 9:00 per mile, and also slowed to a bit over 10:00 mile by 35K. In other words, in the heat, the average man ran the same pace as the average woman late in the race, despite starting out almost 40 seconds a mile faster.
The researchers offered two theories for why women are better marathon pacers, especially in the heat.
First, under any weather conditions, when running at the sub-maximal intensity maintained during a marathon, women might burn a higher percentage of fat than men. If true, this physiological phenomenon would mean that men more quickly burn through their muscle glycogen stores, and be more susceptible to hitting The Wall, marked by a dramatic slowing late in the race.
Second, the researchers say, “women tend to have a larger surface area-to-mass ratio than men, allowing them to dissipate a larger percentage of heat produced by running.”