Endurance Training

In late November 1950, at the height of the Korean War, United Nations troops under the command of Major General Oliver Smith were encircled and attacked near the Chosin Reservoir by a vastly larger Chinese force. Facing total annihilation if they tried to hold their ground, Smith’s men instead executed a fighting withdrawal, puncturing the Chinese lines on the eastern side and escaping to the Port of Hungnam.

On December 4, Smith defended the choice to skedaddle before questioning reporters, saying, “Gentlemen, we are not retreating. We are merely advancing in another direction.” At the time, these words were widely mocked and derided as yet another example of dangerously self-deluding military doublespeak, akin to the later utterance by a U.S. army major in Vietnam, “It became necessary to destroy the village to save it.” But military experts have since come to Smith’s defense, arguing that, although his explanation was technically inaccurate—the troops under his command at the Chosin Reservoir most certainly did retreat—it was true in spirit.

Smith had three options when he found his 30,000 U.N. soldiers surrounded by 120,000 Chinese infantrymen. One was to surrender. Another was to stay and fight to the last man. Both of these options were forms of defeat. In choosing instead to retreat (or, if you prefer, to effect a fighting withdrawal), Smith avoided defeat, and that’s what he was trying to make the press understand with his famous remark.

The expression “live to fight another day” conveys the positive strategic function of retreat. Many times in the history of warfare, a major retreat has been effected by the side that went on to win the war. Examples include George Washington’s nighttime escape from Brooklyn during the American Revolution, the Allied evacuation of Gallipoli in World War I, and Mao Zedong’s yearlong retreat from Chinese nationalist forces in 1934 (known as the Long March). As these examples demonstrate, retreat can be a winning move, but the objective truth of this reality is one thing, getting retreating soldiers to believe and embrace it quite another. And that’s where the hidden brilliance of Major General Smith’s epigram lies.

Anyone who understands the art of war will tell you that morale is a critical element in a fighting force’s performance—every bit as important as weaponry and supplies, strategy and tactics, logistics and communication. I have no doubt that, whether or not reporters believed Smith’s men were “advancing in another direction” rather than retreating, the men themselves did, and because they did, the withdrawal went well. Their leader wanted them to see themselves as fighting to escape defeat or surrender and live to fight another day, not as running away with their tales between their legs.

The principle at work here applies to lots of other things besides warfare, including endurance sports. Just as military commanders prefer to win every battle at minimal cost, endurance athletes prefer to have things go smoothly in their training all the time. Both preferences, however, are unrealistic. Despite their best efforts, military commanders sometimes find their forces surrounded by vastly superior numbers of enemy combatants. Similarly, athletes sometimes encounter rough patches, injuries, illnesses, and other challenges in their training. What matters is how they respond, both tactically and emotionally.

In endurance training, the equivalent of fighting to the last man is stubbornly pushing through rough patches, injuries, illnesses, and the like—brave but doomed. The equivalent of surrender is giving up in frustration, another form of defeat. And the equivalent of retreat is resting or reducing the training load or getting extra sleep or making some other adjustment calculated to maximize the likelihood of a positive final outcome of the process.

Too many athletes wrongly view such adjustments as a kind of defeat also, lumping them together with self-sabotage and quitting. And because they do, they either stand their ground and get slaughtered (metaphorically speaking) or surrender when they would be better off retreating and living to fight another day, or else they go ahead and retreat but do so with a bad attitude, feeling defeated. If I’m describing you, then you need to do for yourself what Oliver Smith did for his troops at the Chosin Reservoir, reframing retreat as something positive.

Someday, God willing, I’m going to write a book called The Little Book of Running Mantras. When I do, it will include a chapter titled “Advancing in Another Direction.” As a coach, I believe that Smith’s fine phrase is highly useful as a self-reminder to runners and other endurance athletes who struggle to embrace “retreat” in their training. Tuck these words away, and deploy them whenever you’re tempted to fight to the last man or surrender instead of retreating, or when retreating threatens to harm your morale. Remember George Washington, and Mao Zedong, and the Allies, and know that, when you take a few days off or make some other sensible adjustment in response to a training setback, you are not going backwards, you are advancing in another direction toward your ultimate goal!

Last year I took part in an online roundtable of running experts. I was the only coach in the group; the others were physiotherapists, kinesiologists, and strength and conditioning specialists. Toward the end of the overlong session, when everyone was a little punch drunk, the conversation degenerated into a sour-toned airing of grievances concerning the inexcusable failings of running coaches. The words “evidence based” were uttered so many times in the course of this verbal savaging of my profession that if the roundtable had been a drinking game with “evidence based” as the trigger phrase, I would have ended up in the hospital with acute alcohol poisoning.

The problem these folks had with running coaches, near as I could tell, was that we aren’t very good scientists. I was strongly tempted to point out that running coaches aren’t scientists at all, in fact, and we should not be judged by the standards used to judge scientists, but I knew that I’d only invite a pile-on if I did so. As it was, the experience left me feeling out of sorts for days. It bothered me that these experts thought they were right about my colleagues when in fact they were so terribly wrong. A phrase came to me—tyranny of evidence based—and it thereafter echoed continuously in my head throughout this period of brooding. I started to feel better only when I googled the phrase and came up with a bunch of links to articles and papers about—are you ready for this?—the tyranny of evidence-based medicine and other clinical practices. I wasn’t alone!

In one such paper, Australian physiotherapist Dave Nicholls wrote, “In recent years, a number of authors have offered significantly more critical commentary on [evidence-based practice]. Spence recently claimed that ‘Today EBM is a loaded gun at clinicians’ heads. “You better do as the evidence says,” it hisses, leaving no room for discretion or judgment. EBM is now the problem, fueling overdiagnosis and overtreatment’ (Spence, 2016), whilst Trisha Greenhalgh et al argued that ‘The evidence based “quality mark” has been misappropriated by vested interests’ (Greenhalgh et al, 2014).”

In a recent blog post of mine, I discussed the difference between knowledge and thinking. Some people are better at absorbing and applying knowledge, I proposed, while others are better at solving problems and figuring things out, and a special few are good at both and an unlucky handful aren’t good at either. Certain professions, including physiotherapy, kinesiology, and strength and conditioning, tend to attract knowers–rote learners who are good at following if/then instructions and who function essentially as body mechanics–whereas other fields, including elite-level endurance coaching, tend to attract thinkers. A large fraction of the body mechanics I’ve dealt with are paint-by-numbers types. They lean hard on evidenced-based practice, in part because they genuinely believe in it but also because they are largely incapable of solving problems creatively and figuring things out for themselves.

Nearly all of the elite-level endurance coaches I’ve ever known are completely the opposite. They don’t know a ton of science, but they can almost always find a way to guide their athletes from point A to point B regardless of how many, or what kinds, of obstacles stand in between. A lot of body mechanics observe these coaches with a mixture of bafflement, disdain, and insecurity. In their minds, endurance training ought to be scientific, and these science-dependent individuals are deeply bothered, sometimes outright threatened, by the fact that the most effective endurance coaches operate more like artists. A certain number of these folks are sufficiently threatened that a one-sided turf war has erupted in and around endurance sports, wherein body mechanics like those participating in the roundtable I just described publicly chastise endurance coaches for being bad scientists in an effort to . . . I don’t know, actually. Take over?

The irony is that these body mechanics would themselves make terrible endurance coaches if they were to steal our jobs. They would be paralyzed by every tricky problem lacking any obvious evidence-based solution that arose in an athlete’s training–and as every coach knows, such problems arise often. They would never innovate or experiment or even treat each athlete as unique because by definition none of these practices can ever be evidence based. Their athletes would come to despise these coaches, who in always deferring to the secular higher power of evidence would lack the charisma—the guru factor—that makes great coaches great, each in a sui generis sort of way. Much of the fun would be drained out of the training process, which would lack any spontaneity or specialness or differentiation from the cookie-cutter training prescribed by every other coach manacled to the immovable steel post of science.

Athletes excel when they believe their coach has a “secret sauce.” If every endurance coach were a body mechanic, there would be no secret sauce. And there would come a time when each athlete confronted their coach, saying, “I swear to God, if you say ‘evidence-based’ one more time . . .”

Here’s an interesting idea for a study: Two dozen coaches and their athletes would be monitored for a period of several months. During this period, researchers would track how often each coach used the phrase “evidence based” in communicating with athletes, who in turn would undergo regular testing to track changes in their level of fitness. I’d bet the farm that the coaches who used that kitten-killing phrase least often would produce the greatest fitness gains in their athletes. And from then on it would be considered an evidence-based practice to avoid saying “evidence-based” in endurance coaching!

Recently I tested a prototype of a wearable device that is intended to help runners monitor and control the intensity of their runs. During my back-and-forth email communications with the product’s lead developer, he sent me a link to a study titled “Intensity- and Duration-Based Options to Regulate Endurance Training.” The abstract began as follows: “The regulation of endurance training is usually based on the prescription of exercise intensity. Exercise duration, another important variable of training load, is rarely prescribed by individual measures and mostly set from experience.” Questioning the validity of experience as a guide to training prescriptions, the authors, a pair of Austrian exercise physiologists, went on to try to establish a more scientific method for determining how long individual athletes should train at different intensities.

The product developer who sent me the link was very approving of the Austrians’ approach. In his message to me he wrote, “When [this method is] paired with the individual’s aerobic and anaerobic threshold intensities, then a fairly complete training prescription can be applied to manage overall load and desired training outcome.” I was a bit more skeptical, replying, “Very interesting paper. So much of effective coaching is based in implicit knowledge and intuition. I think we’re very far away from coming up with a formula or set of formulas that can effectively substitute for these things, but as a coach I’m excited to see this line of research progress and further elucidate exactly what it is that the best coaches are getting right in their training prescriptions.”

I never heard from the product developer again. I believe he decided I was an idiot. If so, the feeling is mutual. Just kidding. He’s a very smart guy, but he comes from a mechanical engineering background, and like a lot of engineers he lacks a proper appreciation for complexity, and as a consequence of this lack he underestimates the power of experience and overestimates the power of theory-based predictions as a tool for solving real-world optimization problems such as endurance fitness development.

I use “complexity” not in the colloquial sense but in the scientific sense. According to Wikipedia (I know, I know), “A complex adaptive system is a system in which a perfect understanding of the individual parts does not always convey a perfect understanding of the whole system’s behavior.” Commonly cited examples of complex adaptive systems (CAS’s) are the human brain, developing embryos, and market economies. What all of these phenomena have in common is that even though they are ordered by relatively simple rules, it is virtually impossible to accurately predict their future states even if these rules are fully known and understood.

The inherent unpredictability of CAS’s presents a challenge for those who, for whatever reason, wish to anticipate or control their behavior. Although it seems reasonable to do so by studying the parts and rules that define the system, in practice this just doesn’t work. What works much better is trial and error, a reality that is very hard for engineers and others with a reductionistic mindset to swallow. And what’s even more galling for these folks is that a system really doesn’t have to be terribly complex for reductionism to fail.

Consider aircraft wing design. If you knew nothing about complexity, you might assume that the best way to design the most aerodynamic wing possible would be to use current knowledge of fluid dynamics to predict the design that is most aerodynamic, then build it, test it, and congratulate yourself on being right. In fact, the most aerodynamic aircraft wings in existence today were designed by trial and error because fluid dynamics—as simple as this phenomenon may be compared to an ecosystem—is too complex for reductionism to work.

To be clear, an airplane wing moving through air does not itself constitute a CAS, but it can be turned into one for the purpose of optimizing wing design. This is done through computer modeling. Engineers create simple programs that generate different designs quasi-randomly, test these designs in simulation, retain design facets that work better and discard facets that don’t work as well, then use this learning to produce a second “generation” of wings, and so on, until the process evolves the most aerodynamic wing possible. While humans are behind this process, they don’t really control it, and the designs they end up with are different from anything they could have come up with via the predictive method.

What does any of this have to do with endurance training? Heck, it has everything to do with endurance training! The problem of optimizing an athlete’s training for endurance performance is very much like the problem of designing the most aerodynamic wing possible. The physiology of endurance performance is extremely complex; place this physiology in the context of a living human being with thoughts, feelings, and emotions and you have something even more complex; place this human being in the context of a life with variabilities in work burdens, family stress, health, weather, and so forth, and you have something far too complex to allow any formula to correctly predict the training that will optimize an individual athlete’s fitness for an upcoming race.

This is not to suggest that training program design is always necessarily a complete shot in the dark. What I am suggesting is that, because of all this complexity, effective training is much more a matter of heuristics (learning and adjusting as you go) than of making great predictions before the process even begins.

Returning to the aforementioned study, I actually like the basic idea that the authors proposed therein. I think their tool could be useful for getting each athlete started on the right foot in his or her training. But I would caution against making too much of this tool or any similar one. Using it would not stop all kinds of surprises from popping up as the training process unfolded, and therefore all kinds of adjustments would be still necessary—adjustments that the tool itself can’t help with.

Nor would the tool even be necessary for getting an athlete started on the right foot. This can be done just as effectively with much less scientific tools. As a coach, all I really need to know is the athlete’s best and/or most recent races times and some basic information about his or her training history. By combining this input with my experience, I can design a program that will yield fairly predictable results. But the real work of coaching begins when the surprises come and I am able to rely on my experience to make adjustments in response to both on accidents that may never recur and to things I learn about the individual athlete’s body and mind, whose influence is recurrent.

For example, I might start off giving a certain athlete two easy days after each weekly interval workout and one easy day after each weekly long run, only to discover that this particular athlete, unlike most, recovers more quickly from intervals than from long runs, in response to which I will adjust his or her schedule to better balance stress and rest for this individual. And here’s an even better example: Often I schedule particular workouts at particular times primarily for the sake of boosting confidence, and only secondarily for some physiological benefit. I’m convinced this practice is effective. Can a one-size-fits-all prescriptive formula based on general human physiology do this? I think not.

Perhaps there will come a day when a computer can coach endurance athletes more effectively than an experienced human coach. After all, computers are already better than humans at chess. But endurance training isn’t chess. With its capacity for implicit learning, the human mind is uniquely suited to the job of training endurance athletes. I understand why folks like the developer of the wearable device I mentioned at the beginning of this post scoff at intuition, which seems so squishy and subjective and non-rigorous to the engineer’s mind, but it is immensely powerful as a tool for real-world problem-solving.

I am reminded of these passages from my book, Run: The Mind-Body Method of Running by Feel:

Malcolm Gladwell’s Blink: The Power of Thinking without Thinking is essentially a book about intuition. In it, Gladwell mentions another book, called Sources of Power, by Gary Klein, which discusses how high-performing professionals in various fields rely on intuition to make good decisions. Gladwell tells a story he heard from Gary Klein about a firefighter who thought he had ESP because he often knew what was going to happen on the job before it happened. One night he and his men were battling a kitchen fire when he suddenly ordered everyone out of the house. He did not know why; he just did it. As soon as they had escaped the house, the floor they had been standing on collapsed. No wonder the firefighter thought he had ESP! But Gary Klein’s in-depth interview with the firefighter, in which he was asked to recall every last detail of the situation, revealed that the firefighter had subconsciously registered various cues that the source of the fire his company was trying to put out was not in the kitchen itself but in the basement beneath them. Through experience on the job he had learned the patterns of different types of fires. And on that night his unconscious seat of implicit learning was able to recognize the pattern of a basement fire and deliver to the firefighter’s consciousness an urgent, intuitive feeling that he and his men were in serious danger and must flee the home immediately.

This story gives us an idea about how we should make intuitive decisions to build confidence through training as runners. The fireman who saved himself and his men by acting on intuition was, of course, extensively trained in fighting fires and brought a system of firefighting techniques to bear in fighting each fire. Nevertheless, most of what he really knew about fighting fires was learned implicitly through experience on the job. This knowledge existed in his unconscious as a capacity to recognize certain patterns before his conscious faculties did, make predictions based on them, and signal these predictions to his consciousness in the form of gut feelings. Similarly, every runner must learn and apply the principles and methods of training that have evolved over many generations as best practices. There are specific ways of training that are generally more effective than others for all runners, just as there are more and less effective ways to fight fires. But each runner is unique, and every day in the life of a runner presents a novel challenge in the quest to improve. Only by learning through experience can the individual runner gain proficiency in customizing his application of the proven principles and methods of training and in making good predictions about how specific training decisions will affect his fitness development. And most of this learning is implicit, as it was with the firefighter in Gladwell’s book. The runner’s subconscious faculties are usually first to figure out what the runner should do next, and communicate their conclusions to consciousness as feelings and hunches.

This has turned into a really long post. Sorry about that. Anyway, I trust I’ve made my point. Enjoy the rest of your day!



If I could clone myself a few times for the sake of taking different paths in life, I would definitely dedicate one of my clones to the pursuit of sports science. This being impossible with current technology, I choose instead to live vicariously through the individual sports scientists who are tackling the questions I would be most interested in tackling if I had my own lab.

One such question (or line of questioning, more accurately) is this: If you could do only one

thing right in your training as an endurance athlete, what should it be? In other words, what is the single most beneficial training practice you could employ as an endurance athlete seeking improved performance? And if you were already doing this one thing, what then is the next most impactful method you could incorporate?

If we were to pursue this line of questioning all the way through to the end, we would end up with a sort of hierarchy of endurance training needs. How useful that would be! Well, guess what? This hierarchy already exists, created by one of my very favorite sports scientists, Stephen Seiler, who drew upon his encyclopedic knowledge of research on endurance training practices to perform the exercise I just described. With a nod to Abraham Maslow’s famous hierarchy of psychological needs, Seiler’s Hierarchy of Endurance Training Needs ranks eight fundamental training practices in order of proven impact. If there’s a more helpful tool for understanding the big picture of endurance training, I haven’t seen it. So, let’s go through the hierarchy (see Seiler’s own graphical summary at the end of this post):Hierarchy of Endurance Training Needs by Stephen Seiler

1. Total Frequency/Volume of Training

According to Seiler, the single most beneficial thing you can do to improve your performance in endurance racing is to train a lot. The fine print is that in training a lot, you must be sure not to train too much, and you can train more without training too much if you train at low intensity, so what Seiler really means here is that the single most beneficial thing you can do to improve your performance in endurance racing is do a lot of low-intensity training.

2. High-Intensity Training

 Although doing a lot of training exclusively at low intensity will make you fitter than doing a small amount of any other kind of training, you will get fitter still if you combine a little high-intensity training with a lot of low-intensity training. Seiler rates this fact as “well established” in the scientific literature.

3. Training Intensity Distribution

Seiler made a name for himself by discovering the 80/20 Rule of endurance training, which posits that endurance athletes improve the most when they do roughly 80 percent of their training at low intensity and the remaining 20 percent (give or take) at moderate to high intensity. So, the next most impactful thing you can do in your endurance training—if you’re already doing a lot of low-intensity training and a little high-intensity training—is to fine-tune the balance of intensities to bring your training in line with the 80/20 Rule.

Let me add here that applying the 80/20 Rule is usually the first change that I make to the training of the athletes I coach. The reason is that the average recreational endurance athlete does close to 50 percent of his or her training at moderate intensity—way too much. Training more won’t help an athlete who is caught in the moderate-intensity rut because it only exacerbates an existing problem. There is much more to be gained from redistributing the training he or she is already doing and then taking advantage of the reduced stress and fatigue levels resulting from this shift to train more.

4. General Periodization Details (Annual)

 Periodization refers to the practice of evolving one’s training over the course of the year in specific ways intended to cause fitness to continually increase. Seiler rates this practice as “likely overrated.” By this I don’t think he means that training shouldn’t evolve over the course of the year but rather that the details don’t matter much. If that’s the case, then I agree wholeheartedly. What does matter is that 1) the overall training workload (which is a function of both the volume and the intensity of training) increase and 2) your most challenging race-specific workouts come later on, when your fitness is near peak levels and it’s getting close to time to race. But the relevant research has shown that within these broad parameters, different periodization practices yield similar results. In other words, where periodization is concerned, there’s more than one way to skin a cat.

5. Sports-Specific and Micro-Periodization Schemes

 According to Seiler, the particular ways in which endurance athletes chose to sequence workouts from day to day and week to week has a “likely modest” effect on fitness. In other words, it doesn’t matter too much whether you schedule recovery weeks every third week or every fourth week. Of course, it’s vitally important that you balance hard work and rest/recovery in such a way that your body neither accumulates fatigue over extended periods nor detrains between challenging training stimuli, but as with macro-periodization, there’s more than one way to achieve this balance.

6. Training-Stimuli Enhancement

“Training stimuli enhancement” refers to practices such as training at high altitude and training in a glycogen depleted state. Seiler believes that such things are worth doing but that the effects are “individual and condition specific.”

7. Pacing Training

Fitness is not the only determinant of race performance. To get the most benefit from any level of fitness in competition, an athlete must pace himself or herself effectively, and this objective is aided by practicing pacing in training, which may also serve to stimulate pace-specific fitness adaptations. Seiler rates this practice as “potentially decisive if everything else is done right.”

8. Training Taper

Although your fitness level won’t change much in the last week or two before a race, no matter what you do, what you do in the last week or two before a race can have a big impact on how you perform nevertheless. Tapering is the art (Stephen Seiler might say science) of altering your training prior to competition to ensure that you’re rested—but not too rested—and physiologically primed for a maximal effort. Science has shown clearly, for example, that endurance athletes race better when they include high-intensity work in their taper than when they do everything at low intensity. Seiler rates tapering as “potentially decisive if you have one isolated competition. . . and everything else is done right.”

Learn more here: https://www.researchgate.net/profile/Stephen_Seiler/publication/310725768_Seiler%27s_Hierarchy_of_Endurance_Training_Needs/links/583590c208ae004f74cc51f5/Seilers-Hierarchy-of-Endurance-Training-Needs.pdf


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