Wilson Kipsang won the Tokyo Marathon on March 1 with the time of 2 hours, 3 minutes and 58 seconds. The Kenyan broke the Japan record for the race, but did not beat his personal best of 2:03:23, which was a world record he set at the 2013 Berlin Marathon. Nor did he best the current world record of 2:02:57, currently held by fellow Kenyan Dennis Kimetto.

Kipsang, enjoying the cool temperatures of Tokyo, thought he could take back the world record. But he likely did not believe he had a chance at running under 2 hours. Getting to 1:59:59 is the holy grail of long-distance running. According to this in-depth look from the New York Times at “Sub2”, as this quest is called, a researcher from the Mayo Clinic thinks that breaking the 2-hour barrier won’t happen for another 10 to 25 years, and a three-time Olympian from Ethiopia, Bekele, says “I can’t say it’s possible.” As the article explains, “Could the body have enough carbohydrate fuel to run that far, that fast? Would the brain slow the legs for self-preservation?”

A 1:59:59 marathon would require a searing pace of 4 minutes 34 seconds per mile, seven seconds faster than the pace of the current world record. It would require 85 to 90 percent of a runner’s maximum aerobic capacity — twice the capacity of an average man — and a sustained heart rate of about 160 to 170 beats per minute. (The typical resting rate is 60 to 100 beats per minute.)

It is beginning to feel a bit like Zeno’s Paradox, that no matter how close you get to your target, you may never reach it. Could the 2-hour marathon be a bridge too far? Sports scientist and anti-doping expert in the IOC, Yannis Pitsiladis, believes that a Sub2 marathon is possible. “What excites me is understanding the limits of human performance. What can man do?”

Pitsiladis believes we’ve only just scratched the surface in understanding the science of endurance running. Incremental gains in the disciplines of nutrition, biomechanics, genetics, running efficiency, training, race strategy, sports medicine, as well as data analytics could get runners to the tipping point of dramatic advances in long-distance running. “We know nothing about the science of training,” Pitsiladis said. “I really mean nothing. When I say that, people get really upset.”

Here are a few of the non-conventional ideas of Pitsiladis from that New York Times article:

• How Many Miles: Many elite marathoners, for instance, run about 120 miles a week in training. But there was little science to support that regimen, Pitsiladis said. Perhaps 75 miles a week would work just as well for many runners — or maybe any reasonable training program would.
• Live High Train High? A popular training method is known as “live high, train low.” By living at a higher altitude, athletes stimulate the production of red blood cells to compensate for the lower level of oxygen in the air. By training at or near sea level, they are able to maintain the intensity of their workouts because more oxygen is available. Live high, train low is supported by some evidence. But Pitsiladis is not fully convinced of its efficacy, saying, “I would bet you it’s wrong and that what’s better is live high and train higher,” as perhaps the two greatest distance runners in history — Haile Gebrselassie and Kenenisa Bekele of Ethiopia — often did.
• Be a Glutton for Glucose: Pitsiladis had come to believe that a two-hour marathon might be best achieved by bombarding the system with glucose.For instance, Owen Anderson, a consultant to the Sub2 Project who coached elite Kenyan road runners in Michigan, gave his athletes eight to 10 ounces of a sports drink about 10 minutes before a race to get accustomed to a bloated feeling. (They drank more during competition.)
• Run the Second Half Faster: Against convention, Pitsiladis theorized that the second half of a two-hour marathon would be run faster, not slower, than the first half. As runners burn fuel and become lighter during a race, he said, they should become more economical, needing less oxygen to maintain a certain speed.
• Squeeze Don’t Twist: When runners drank, Pitsiladis believed, they could shave precious seconds by squeezing fluid from a bag instead of opening a bottle, as elite runners do on the course.
• Rinse Don’t Drink: And perhaps, he said, they needed to drink little or nothing in the second half of a two-hour marathon. Instead, they might rinse their mouths with a carbohydrate solution and spit it out. Research showed the brain could be tricked into believing that more carbs were on the way, thus inducing the muscles to work harder.