The Generation that is Breaking the Law of Diminishing Returns
The Law of Diminishing Returns prescribes that the faster we run, the more marginal subsequent improvements will be. This makes sense: it is conceivable that a four-hour marathoner will one day become a three-hour marathoner, but it is not possible for a two-hour marathoner to improve by a similar amount.
Tigst Assefa has just joined an elite group of female runners currently upsetting the Law of Diminishing Returns by becoming the first woman to break 2:12 for the marathon. And 2:13. And 2:14. On Sunday morning, the former 800m runner from Ethiopia obliterated the marathon world record by two minutes and eleven seconds. The last time it was broken by such a margin was in 1983.
Tigst Assefa breaks the women’s marathon world record by more than two minutes at last Sunday’s Berlin Marathon
(Photo Credit: ©SCC EVENTS/Jean-Marc Wiesner)
While Ethiopian women are well-represented on the all-time list, Assefa is the first to hold the world record. Notably, her time is also faster than the lifetime best of Abebe Bikila, a male runner from Ethiopia often credited with igniting the ever-successful African running scene. At the 1960 Olympics, Bikila ran barefooted to marathon victory to win Ethiopia’s first-ever Olympic gold medal. Four years later, he became the first person to successfully defend an Olympic marathon title, running 2:12:11 and setting a new world record in the process. Less than 60 years later, an Ethiopian woman has run faster than Bikila ever did.
Ethiopia’s Abebe Bikila winning the men’s marathon at the 1964 Olympics
On Sunday morning in Berlin, powered by a shoe capable of reigniting the “supershoe” wars – an AUD 800, single-use shoe produced by Adidas – Assefa moved clear of her competitors after just 15km. She reached the halfway point in 1:06:20, only to improve in the second half to a 1:05:33 – a time that would have set the half-marathon world record as recently as a decade ago.
While Assefa was in a class of her own in the women’s race, she had company throughout, with male pacer Girmay Birhanu Gebru ushering her along for almost the entire distance. She also picked up some unexpected assistance from American Jared Ward — sixth in the men’s race at the 2016 Olympics — who was caught by Assefa at 28km and ran with her until the final kilometre.
“I kept checking my watch as I could hear her getting closer,” exclaimed Ward after the race.
“I couldn’t believe that she was on 2:12 pace! I first had a thought to stay out of her way, and then I wondered if I could help. She looked so smooth. And then, the last 5km, she certainly helped me!”
Kenya’s Sheila Chepkirui finished a distant second in 2:17:49, almost six minutes behind Assefa, while Tanzania’s Magdalena Shauri ran 2:18:41 to add a national record to her bronze medal.
Assefa is not the only one taking uncharacteristically sizeable chunks out of women’s world records: this generation of female track runners have been achieving similar feats. In 2021, the 10,000m world record dropped more than 16 seconds – something that had not happened since 1986. This year, the 5000m world record was lowered by a margin unseen in more than 15 years, and the 1500m world record improved more significantly than it had since 1972.
The margin by which Assefa bettered the marathon world record is also ridiculous, and it is hard to explain why these records are suddenly falling so drastically. However, the idea of a woman running 2:11, regardless of what her competitors are capable of, may not be as outrageous as it seems.
A study conducted by the International Association of Ultrarunners analysed the results from more than 15,000 ultrarunning events over a 23-year period. They found that “the longer the distance, the shorter the gender pace gap.”
Why women tend to run comparatively faster over longer distances remains unclear. Experts have cited hormonal and chromosomal genetic differences as one possible explanation, pointing out the different capabilities of testosterone and oestrogen. Abundant in male bodies, testosterone is extremely useful when generating power and strength. Alternatively, oestrogen, which has a much higher presence in females, helps protect muscle membranes. This protection allows the muscles to function more consistently and without as much fatigue over long races. This may explain how Assefa was able to run faster in the second half of the race compared to the first, whereas male athletes like Eliud Kipchoge consistently slow down at the backend of a marathon, even during world record performances.
The researchers explained that “on average, in five kilometre running, men are 17.9% faster than women, at marathon distance the difference is just 11.1%, 100-mile (106.9km) races see the difference shrink to just 0.25%, and above 195 miles (313.8km), women are actually 0.6% faster than men.”
These percentage differences do not carry cleanly over to elite runners, but the trend remains the same: the further we run, the smaller the gap between male and female performances. The 1500m and 5000m men’s world records are both 10.10% faster than the women’s, whereas over 10,000m, that gap shrinks to 9.77%, and over the half marathon it sits at just 8.51%. Before Sunday, the men’s marathon world record was a trend-bucking 9.63% faster than the women’s: now, that margin is 8.14%.
These graphs allow us to visualise those numbers, plotting how much faster men’s world records are than women’s over distances ranging from 1500m to 100km. The graph on the left includes the marathon world record prior to Assefa’s performance, while the right incorporates the new world record. As insane as Assefa’s time seems, there is no denying it fits the trend far more accurately.
This suggests that Assefa’s astonishing performance on Sunday may have been the result of an immense psychological breakthrough that accompanies running a world record, rather than her obliterating some physiological barrier that separates men and women. An in-depth analysis of these trends and their implications is outside the scope of this article: however, if they hold true, we can expect a handful of women to go under Brigid Kosgei’s old mark of 2:14:04 in upcoming races.
You can access the results of the 2023 Berlin Marathon here.