When Kenenisa Bekele set world records in the 5000 and 10,000 meters, he probably didn’t think they’d last more than a few years.
After all, the Ethiopian track star achieved those feats in 2004 and 2005, respectively, and in those days, runners set new global standards every few years.
Nearly a decade later, however, Bekele’s times have yet to be bested, and according to a new study by a team of Mayo Clinic researchers, advances in drug testing could be the reason.
As Runner’s World reports, running expert Michael Joyner, MD, focused on data from the 5000 and 10,000 meters and found that between World War II and the present, records in each event have tended to last about three years. That Bekele has held onto his crowns for nearly a decade is quite unusual.
In the 1990s, records often fell on a yearly basis, and given that this was the era of widespread synthetic EPO usage—at least in the Tour de France and other pro cycling races—researchers believe that there could be a correlation.
Rather than just look at world records, Joyner and his colleagues examined the 50 fastest times each year since 1980, and the results from 2006/2007 onward are surprising.
“There has been no statistically significant increase in speed,” according to the paper.
A similar stagnation in cycling further supports the hypothesis that drug screeners have gotten better at detecting performance-enhancing substances. But according to the Mayo team, there are three other possibilities.
First, it could be that distance runners are finally reaching the limits of what humans are capable of. Bekele ran the 5000 and 10,000 meters in 12:37.35 and 26:17.53, respectively, and one theory holds that human beings simply aren’t equipped to go faster.
It might also be that distance runners have turned their attention from the track to the marathon, where there’s more money to be made. Lastly, recent years have brought few significant advances in equipment or training.
The phenomenon might also be the result of all four factors, as Joyner posited in a Runner’s World interview.
"We have looked a little deeper at the running performances, and I don’t think this is a statistical artifact,” he said. “I think it's caused by all of our conclusions.”