With his seemingly effortless victory in the Olympic Marathon steambath in Japan, Eliud Kipchoge ended the debate. There’s no longer any question that he’s the Greatest Of All Time (GOAT) at the distance. How do you argue against a guy who has won back-to-back Olympic golds, holds the official marathon world record (2:01:39), and has covered 26.2 miles in an “exhibition race” in 1:59:40?
You don’t. That leaves one endlessly intriguing question: Why? Why is Kipchoge so much better than everyone else?
Three decades ago, sports geneticists like Claude Bouchard of the Heritage Family Study believed the answer was close at hand. They assumed that the Human Genome Project had opened a previously-closed door. Surely they would soon be able to identify specific genes linked to everything from sprint performance to marathon records.
However, this hasn’t happened. Instead, experts now acknowledge that elite performance is a “multifactorial” phenomenon — meaning that it’s somewhere between extremely complicated and completely unknowable.
The truth is, no one can fully explicate why Kipchoge is the GOAT. There’s no simple answer and no single ingredient. Heck, we don’t even know if he’s grimacing in pain at the end of his marathons, or smiling because he has read studies claiming that a smile helps you run better.
Even the researchers most familiar with marathon physiology and Kipchoge himself can only marvel at his seemingly-ageless achievements while they enumerate some of the factors — from VO2 max to muscle fibers to biomechanics — that may underlie such greatness. Here’s a review of their thinking, and observations from a few others.
Training: Does it make a significant difference?
We runners are obsessed with training, because it makes a huge difference in the performance of beginning and intermediate runners. This isn’t necessarily true for elites. Their training is relatively similar, with almost everyone logging 100 to 120 miles per week. Few dare to do less, and no one has climbed the Olympic Marathon podium proclaiming, “I owe it all to my 150-mile weeks.” The great ones find the squeaky-tight balance between just enough and over the top.
As far as we know, Kipchoge trains long and hard, probably around 120 miles per week. At the same time, he has said that he rarely extends himself beyond 80 percent in training. He understands that racing is the thing, not impressive Instagram workouts. He also knows when to chill. (We’ll get to that).
The classic model — VO2 max, lactate threshold, and running economy
Way back in 1991, when the marathon world record stood at 2:06:50, Mayo Clinic endurance expert Michael Joyner wrote a paper proposing that it was theoretically possible to cover 26.2 miles in 1:57:58. (Many of us fell to the floor laughing at this notion.) Joyner said such a runner would need a combination of high oxygen consumption, high lactate threshold, and, especially, great running economy. “This analysis suggests that substantial improvements in marathon performance are ‘physiologically’ possible,” he wrote at the time.
Today, we’ve stopped laughing at Joyner. While he hasn’t seen any of Kipchoge’s lab data, he notes: “My guess is that he fits well with my original model.”
Joyner has also changed his thinking on the Big Three factors. He once pegged a marathoner’s top lactate threshold pace at about 85% of max. He now thinks 90% is likely. Which implies that he believes someone can run faster than 1:57.
England’s Andy Jones, a noted exercise physiologist and researcher, consulted with Nike on the Breaking2 project. This makes him one of the very few privy to Kipchoge’s raw lab data. But he can’t comment on specific results; that would violate scientific-medical ethics.
Still, Jones can make general comments like: “Needless to say, Kipchoge’s combination of the three values was one of the best among the athletes we tested.”
Several decades back, Jones also tested Paula Radcliffe annually to assess any changes in her physiology. Radcliffe set a world record in 2003, running 2:15:25, since bettered by Kenyan Bridget Kosgei (2:14:04). Jones observes that Radcliffe and Kipchoge are “very similar. They have all the same credentials: high VO2 max, high LT, great RE (and high CS). Paula, with her bobbing head, wasn’t as smooth looking as Kipchoge, but she was exceptionally economical, so her head didn’t adversely influence that.”
Critical speed — the new kid on the block
Jones likes a newer endurance metric called critical speed (CS), and he thinks this is where Kipchoge shines especially bright. CS is similar to what you might think of as Lactate Threshold pace or Tempo pace. The higher a marathoner’s CS, the longer and faster s/he can run without hitting the wall. (At Outside Online, Alex Hutchinson takes a deep look at CS, including Jones’s work in the area.)
“Kipchoge’s critical speed is almost certainly higher than anyone else’s,” Jones told me. “So at 2:10 marathon pace, he’s much further below his critical speed than other athletes.” In other words, he’s under his red-line pace; he can keep going.
An important aspect of CS is the way it declines after about two hours. Your critical speed might be 10 (not a real number, but used for illustration only) at the beginning of a marathon, but only 6 after two hours. So when you start out running at 8, you’re comfortable. After 20 miles, things change. If you try to maintain that 8 effort now, you’re bucking up against your CS of 6. Result: You bonk, you hit the wall, sayonara.
Jones points out that this is essentially what happened in the Olympic Marathon. Kipchoge had a fair amount of company in the first half of the race, including Galen Rupp. But everyone else faded away when Kipchoge picked up the pace from 30K to 35K (running 14:28 for 5K). He was still running slower than his CS; everyone else had stepped over the red-line.
Here’s a short video that illustrates how Kipchoge kept going while the others couldn’t. Watch how the red dot, the lead pack, explodes into multiple pieces when Kipchoge exerts himself at 30K. Jones notes that CS probably becomes even more important in hot conditions.
— Tomoyuki MARUYAMA (@Tom1jpn) August 8, 2021
Jones poses and answers the essential question himself. “So the big question becomes, what determines CS? Essentially it’s a metric that combines an athlete’s highest sustainable oxidative metabolic rate, mainly related to muscle oxidation (mitochondrial capacity plus the cardiovascular ability to deliver lots of oxygen to the muscles) and running economy.”
Fatigue resistant muscle — the fourth component
In his ground-breaking 1991 paper, Michael Joyner admitted that there were things at play he couldn’t yet explain. One of these has come to be known as “muscle fatigue resistance.” Do some runners have muscles that just don’t get as tired as yours and mine? Joyner wondered if some champion distance runners manage to use more of the fast-twitch fibers usually reserved for sprinters. “And if recruited,” he wrote, “can these fibers be trained to fire and contract repeatedly for several hours without fatigue?”
Jones agrees that fatigue resistance could be an important-but-little-
Anatomy: Small is beautiful
When geneticists and exercise physiologists failed to fully explain extreme marathon performance, other scientists waded in. They measured Achilles tendon energy return, lower leg (calf muscle) mass, short toes v long toes, and so on with varied results.
We have solid evidence that a smaller overall body size (height, weight, BMI) is conducive to faster marathons. This table shows that male Olympic Marathon winners cluster around a height of about 5’6”, a weight of about 125 pounds, and a BMI of about 19. The table shows Kipchoge weighing 11 pounds less in 2021 than five years earlier, which seems unlikely, but his body size is similar — small — to many other marathon greats.
Top marathoners tend to be smallish because it improves their efficiency, may limit injuries, and enhances thermoregulation. This last factor is especially important in summer marathons at the World Championships and Olympics.
Tall marathoners are not unknown, but they are rare. It was easy to spot Galen Rupp in the recent Olympic race because he is 5’ 11’ tall, towering over most of his competitors. And four-time Boston Marathon champ Robert Kipkoech Cheruiyot is 6’3” tall. They are exceptions to the general rule.
Spanish endurance researcher Alejandro Lucia is well known for several classic studies of Tour de France riders and distance runners. He has sometimes collaborated with both Jones and Joyner. In one study Lucia compared world class Spanish runners with Eritreans. The two groups had roughly the same VO2 max, but the Eritreans were smaller, with longer legs and skinnier lower legs. This combination gave them a superior running economy.
“I believe Kipchoge follows an excellent, high-carbohydrate diet and has lean legs, like many Kenyans,” says Lucia, “This means he can race at a pace that represents a smaller percent of his VO2 max than the others. Also, his heart is not challenged when delivering oxygenated blood to the working leg muscles, the brain, and to the skin for thermoregulation.”
Leg stiffness: Does it increase leg swiftness?
“Four months ago, Scientific Reports published a paper by University of Michigan biomechanics researcher Geoff Burns in which he found that elite milers run with “stiffer” legs than highly trained but slower milers. Burns says that “leg stiffness” is a measure of how a runner compresses and decompresses while on the ground.”
A stiff running body is one that “pops” off the road without first compressing very much under the impact of each stride (the opposite of stiff-body running is Groucho-running, in which the knees bend in an exaggerated fashion.) The pop comes from great body elasticity in the tendons and ligaments, as well as from full body tension and muscular coordination.
In a forthcoming study, Burns and collaborators from South Africa compared the leg stiffness of some very fast Kenyan 10K runners (about 28 minutes) with recreational runners (about 43 minutes.) The Kenyans had a much higher relative stiffness (per body weight). They also had force patterns that more closely resembled simple, efficient bouncing systems.
“The Kenyans coordinated their bodies to behave more like simple pogo-stick-like systems,” Burns says. “I suspect Kipchoge does the same, where he orchestrates his myriad body and limb movements to have very efficient, coordinated energetics on the ground, bouncing exceptionally well.”
Bounce? It doesn’t look like it when you observe Kipchoge’s form.
(This video shows the last several minutes of his 1:59 marathon.) He and other top runners waste little energy with unnecessary bouncing. This is what greater stiffness looks like — less compression against the force of the ground — and it’s a common feature of efficient running. And a pogo stick, Burns says, is an “ideal” system that perfectly recycles all of its energy bounce-to-bounce. He adds: “No runner is a perfect system, Kipchoge included, but one with an appropriately stiff ‘spring’ and coordinated forces may be losing less energy step-to-step.”
The Bill Rodgers view: Altitude plays a major role
The one time King of the Roads has been studying top marathon performances ever since he won his first of four Boston Marathons in 1975. Rodgers also won four times at New York City, and has a marathon best of 2:09:27. For him, real estate has always explained more than anything else. “I think it’s location, location, location,” he says, referring to the high altitude births and lives of East African runners.
“Other circumstances, like financial support, goes a long way in poor countries,” he continues. “Those athletes don’t have much opportunity, and even modest prize winnings are a big deal to East Africans. Lastly, I think Eliud is just a strong looking runner in every way. He’s not big, but he’s strong physically, and has a strong mind too. I think it’s this combination of qualities that allows him to keep winning.”
Final frontier — the mind of the master marathoner
While there’s no simple test to measure the marathoner’s mind, everyone who has ever met Kipchoge has been impressed by his zen master, Yoda-like approach to life and challenge. He even looks like Yoda, with his wizened, deeply-lined face. More importantly, Kipchoge lives simply, embraces hard work, studies sport as well as success in other realms, and apparently knows few fears when it comes to pushing the boundaries. As he likes to say, “No human is limited.”
To all this, I can add a personal anecdote. In 2005, my wife and I were part of a small group of American runners visiting Kenya’s Rift Valley and the training camps of the top athletes. We spent one afternoon with Kipchoge’s group in Kaptagat (8000 feet), including a 4-mile run with the Kenyans, followed by the requisite tea drinking.
My wife is an avid but slow runner, and she worried how the hills and altitude would affect her. So I asked the assembled dozen or so Kenyans if anyone would be willing to accompany us at about 11:00/mile pace. Kipchoge raised his hand and stepped forward, a relaxed smile on his face. He was just 20 then, and wouldn’t run his first marathon for another eight years. Still, the summer before he had dipped down to 3:50 mile in the mile, and 12:46 for 5000 meters. Talented? You might say so.
Everyone else set off at a much faster clip, but Kipchoge stayed at our sides the whole way. I don’t think many other elites would have or could have done this. They are too driven, especially in their development years. But Kipchoge was preternaturally wise even then; he knew one slow 4-miler would not derail his running career.
I don’t remember our conversation on that run, except for one question. I asked if he worried, in racing the great Ethiopians like Haile Gebrselassie, about their explosive finishing kicks. Kipchoge chuckled. “No, I do not worry about that,” he replied. “I am plenty fast enough myself.”