It might happen, but it won’t happen anytime soon.

Soon after Wilson Kipsang broke the world record in the marathon with a 2:03:23 effort at the 2013 BMW Berlin Marathon on Sept. 29, almost immediately the running community around the world started asking about when the first sub-2-hour marathon might occur.

As cool as that sounds, it’s probably not as close as most people think. Kipsang averaged an extraordindary 4:42.33 pace per mile throughout the race to shave 15 seconds off the previous record. However, to run a marathon in 1:59:59, a runner would have to average 4:34.46 per mile, which is dramatically faster — more than 25 seconds faster for every 5K split.

There are many reasons why a sub-2-hour marathon isn’t going to happen anytime soon, sports scientist Ross Tucker, Ph.D., says on his blog, The Science of Sport. A sub 2-hour marathon would mean a runner would have to run sub-60 seconds for each half. The current world record in the half marathon is 58:23, but only a handful of runners have ever broken 59 seconds. So expecting a runner to run within 90 seconds of world-record pace for the half marathon and then double that effort over 26 miles is very unlikely.

In the meantime, there’s plenty to analyze about Kipsang’s amazing effort in Berlin, Tucker says.

If you break his race into quarters, you get the following for his 10K splits:  29:16 – 29:03 – 29:42 – 29:11 (plus that final surge).  The “shape” of that race looks like a typical mile WR – Fast start, slowest in the third quarter, and then the surge.  It was an excellent management of his physiological resources.

In terms of where improvement can come, Kipsang finished very fast, which might mean he has the ability to go slightly faster, Tucker says. But not by much. Having a reserve for an elite marathon is being able to go 4-5 seconds per kilometer faster, and so it really is on the limit.

Kipsang is also 31, in his fourth year of marathon running, and set this WR in his seventh race, which, Tucker says, is a long time to reach a peak.  Typically, the fastest marathon of an athlete’s career happens between 2 and 4, though there are exceptions (Haile Gebrselassie took a while to perfect the race, and then improved steadily into his late 30s). Kipsang then, may follow a similar approach, and improve again, but the “safer bet,” as it always is, is that he won’t.

And a sub-2-hour marathon? It might happen, but it won’t happen anytime soon.

More: The Science of Sport