For most runners, a marathon is about settling in for the long haul, finding a comfortable pace and pushing through epic mental and physical walls. For elite athletes, the 26.2-mile race is rapidly becoming just another sprint.
In September, Patrick Makau of Kenya set a new world record at the Berlin Marathon, with a time of 2:03: 38 seconds. With an average pace of four minutes and 43 seconds per mile, Makau beat the previous record by an astounding 21 seconds.
As the fall marathon season heats up and tens of thousands of runners prepare to run the ING New York City Marathon in November, speculation is again rising about whether a sub-two hour marathon might some day be possible.
According to most experts, it's not a matter of if marathoners will one day break that barrier. It's a matter of when. One reason is that running is becoming popular enough to attract an ever-wider genetic pool into the sport.
"World records continue to improve for a lot of distances, and it's just because you get more talented athletes entering into the event," said Edward Coyle, director of the Human Performance Laboratory at the University of Texas, Austin. "As time goes by, you get more and more athletes who have participated. It's simply a probability statement."
American runner John Hayes became the marathon’s original world-record holder after winning the race in its first Olympics appearance in London in 1905, according to this website. His time was 2:55.18.
Record times dropped precipitously at first, with runners regularly smashing the bar by a good five or 10 minutes. By 1909, the fastest time had fallen to nearly 2:40. By 1920, it was close to 2:32.
After a several decade-long plateau with only marginal improvements, runners began to train year-round with much higher mileage. As a result, records dropped to about 2:15 by the end of the 1950s. By the end of the 60s top times fell to about 2:08 by the end of the '60s.
The next set of incremental speed boosts came in the '80s, said Michael Joyner, an anesthesiologist and exercise researcher at the Mayo Clinic in Rochester, Minn. Improvements in sports medicine, shoe technology and nutrition all helped. Perhaps more important, marathons boomed in popularity.
In 1991, Joyner published the first scientific paper to ask the question: How fast could a human body possibly run a marathon? By factoring in what’s known about physical limits of the human body, he reported in the Journal of Applied Physiology that it was theoretically possible to run the race in 1:57:58.
A follow-up paper, published last year in the same journal by Joyner and a colleague, predicted that the first sub-two hour marathon will probably happen sometime between 12 and 25 years from now.
The top marathoners in recent years have come from East Africa, where many grow up running hours every day at high altitude. And while there’s no way to predict exactly who the first runner to break the two-hour barrier will be, he is likely to have a few key physical traits.
First, he'll need to have a high VO2 max, which essentially measures how good the muscles are at turning oxygen into fuel and is comparable to horsepower in a car. Elite marathoners already generally have twice the VO2 max of average college-aged men.
But the runner with the highest VO2 max is not the one who ends up winning. The sub-two hour marathoner of the future will have to be able to sustain a high percentage of his VO2 max for a long time. An average athlete who runs 10Ks, Coyle said, can usually sustain a level of 65 to 70 percent of his limit. Elite marathoners have been measured at 88 percent for the whole distance.
Also important is running economy, or the ability to maintain a certain speed for a given amount of oxygen used. Coyle pointed to Paula Radcliffe, who holds the women's world record of 2:15:25. Over about 12 years, Coyle said, Radcliffe was able to drop her average mile rate from 6:18 to 5:18 for the same amount of effort.
But even if a marathoner has the right blend of genetics, training and nutrition, he needs to be healthy on the day of the race. His mind has to be in the right place, too, as marathoners don't have the luxury of running their race many times a year. Pacesetters who block some wind will help.
Weather conditions also have to be just right. A windless, cloudy, 50-degree day is ideal, Joyner said. The course, which has to be a loop to meet record regulations, also needs to be flat. That probably explains why the last few records have fallen at London and Berlin, which are devoid of hills.
The New York City marathon, which is a point-to-point course, is far too hilly and its weather is too inconsistent to be conducive to a sub-two hour marathon. So far, no one has run faster than 2:07:43 in the five-borough race.
Still, the fact that a growing number of people continue to sign up to run New York and other marathons suggests that a two-hour marathon is becoming within reach. Instead of playing soccer or basketball, athletes with the most running potential are now more likely to choose running as their sport.
And even though two hours is an arbitrary barrier to strive for, the push to break it helps highlight the amazing potential of the human body.
"Whenever people have attempted to place limits on what humans can do, humans always do a little better," Joyner said. "If you make barriers, people are going to try to break them, whether it's going to the moon, flying across the Atlantic, trying to set an age-group record or becoming the oldest person to do something. It's who we are."