Psychobiological Model – 80/20 Endurance

If you could choose one athletic superpower to exploit in your future training and racing, what would it be? Here’s the rule: Your superpower has to be a natural human trait that actually exists in some athletes, not a magical attribute like Pogo Feet or Turbo Mode. Potent, yet real.

If I were I to collect a hundred answers to this question from everyday athletes like you, I would be surprised if a plurality didn’t choose toughness (or resilience or grit) as their superpower. That’s not a bad pick. Toughness is very useful in endurance sports. But as a coach, I believe there’s another trait that is even more useful as an athletic superpower: restraint.

Surprised? That’s understandable. But give me a chance to explain what restraint can do for an endurance athlete, after which, I’m confident, you’ll agree that it is the best superpower one could possibly have. First, though, let’s talk about two other traits that are highly useful to endurance athletes: motivation and judgment.

Motivation is critically important in both training and racing. To achieve maximal performance in competition, athletes must attain maximal fitness in training, which requires that they put in large volumes of work with great consistency, which in turn demands a very high level of motivation. In a 1987 interview, six-time Ironman world champion Dave Scott said, “I had this idea that if I trained more than anyone else, I was bound to succeed.” It’s one thing to have this idea, quite another to execute on it. Dave was able to because he had an unmatched desire to train.

In races, motivation contributes directly to performance. According to Samuele Marcora’s psychobiological model of endurance performance, endurance performance is limited not by physiological factors such as lactate buildup, which merely constrain performance, but by psychology. A 2010 overview of the theory describes it as follows:
The Psychobiological model is based on the Brehm’s Motivational Intensity Theory, which consists of two main constructs: potential motivation and motivation intensity. Potential motivation refers to the maximum effort a person is willing to exert to satisfy a motive (e.g., to succeed in the exercise task), while motivation intensity is the amount of effort that people actually expend. The Brehm’s Motivational Intensity Theory postulates that individuals will engage in a task (i.e., exert effort) as long as: a) the level of potential motivation is not reached; or b) the task is still viewed as possible. If the former is reached or the task is perceived as impossible, individuals should disengage from the task. In the light of the Psychobiological model, the point of exhaustion during exercise is a form of task disengagement, in which individuals will exercise until a) the perception of effort raises to the critical level set by the potential motivation; or b) believe to be physically unable to maintain the task. In the latter case, they believed to have exerted a true maximal effort, and the continuation of exercise is perceived as impossible.

As you see, motivation is the lynchpin of this particular model of endurance performance, which has received a lot of experimental validation since it was introduced. For example, a 2020 study led by Ian Taylor of Loughborough University found that, within a group of forty athletes, those who scored higher on a measure of autonomous motivation reported “lower temptation to reduce effort and higher value of goal pursuit” in a 10-minute cycling task and also performed better in that task. When the limit is psychological, psychology moves the limit.

There’s less research on the influence of judgment on outcomes in endurance sports, but do we really need it? I see it every day in my work as a coach. The majority of recreational endurance athletes self-limit in various ways as a consequence of imperfect judgment. They spend too much time training at moderate intensity, don’t vary their workouts adequately, race too often, put little thought into their training plan selection, blow their pacing in workouts, fail to modify their training appropriately based on how their body has responded to completed training, follow fad diets instead of eating like the elites, the list goes on. True, some of these bad decisions can be attributed to naivete, but others continue to be made even when athletes know better and therefore must be attributed to poor judgment. Athletes who possess or develop good judgment learn to avoid such mistakes, and they benefit tremendously as a result. It really pays to have good judgment as an endurance athlete.

The reason restraint trumps both judgment and motivation as an athletic superpower is that it essentially combines these two things. By definition, restraint is a conscious act of resisting an impulse, and an impulse, by definition, is a motivated desire to perform a specific action. Without motivation, therefore, there is no need to exercise restraint. Nor is there a need to exercise restraint when a particular impulse is judged to be consistent with a person’s larger objectives. Only when an impulse contradicts such objectives—as when a person who’s sworn off alcohol feels an impulse to have a glass of wine—is restraint called for.

So you see, an athlete must be both motivated and capable of making good decisions to exercise restraint. This makes restraint a superior virtue to motivation alone, which often results in foolish risks, and judgment alone, which is of as little use as a steering while without an engine.

I will illustrate the rewards of exercising restraint and the consequences of failing to do so with a pair of excerpts from my book On Pace: Discover How to Run Every Race At Your Real Limit. First the consequences:

Professional triathlete Jesse Thomas came into the 2016 Ironman World Championship with a solid plan. On the basis of prior experience at the Ironman distance as well as recent training performance, he had identified a power target that he intended to sustain throughout the bike leg. A strong runner (he’d won state championships in track and cross country in high school and earned All-American status in the same sports at Stanford University), Thomas needed to ride hard enough to avoid giving up too much ground to the competition but not so hard that his legs had nothing left for the marathon, and his power target struck this balance.

It was a sound plan. But when he got out onto the bike course and found himself being left behind by uber-cyclists Sebastian Kienle and Michael Weiss, Thomas cast aside his pre-race strategy and gave chase. Upon reaching the 60-mile mark in the hilltop village of Hawaii, Thomas discovered that his average power output up to that point exceeded not just the target he’d set but also his average power in a recent race of half the distance, Ironman 70.3 Santa Cruz.

“And then I just completely crumbled,” Thomas told a reporter for Triathlete after his disappointing 16^th-place finish. “It was a long, long, long day.”

Now the rewards:

An historical counterpoint to Jesse Thomas’s long, long, long day at the 2016 Ironman World Championship was Mark Allen’s performance at the same event nineteen years earlier. It was Allen’s swan song as a professional triathlete, a do-or-die attempt to match his former rival Dave Scott’s record six world titles at age thirty-seven. Cycling power meters did exist back then, so Allen’s plan for the bike leg was to keep his heart rate at or below 150 beats per minute, a number that, like Thomas’s wattage target, he’d arrived at through experience. In the early miles, Allen lost his lead to a pair of younger Germans, the strongest of whom, Thomas “Hell on Wheels” Hellriegel, eventually built a seemingly insurmountable advantage of 13:31 over the five-time champion. But Allen didn’t fall so far behind because he couldn’t go faster. Rather, he lost ground because he chose not to go faster, knowing that sticking to his plan gave him the best chance of winning, regardless of what anyone else did. Resisting the temptation to push harder wasn’t easy, but Allen’s Ulysses-like discipline was rewarded when an overcooked Hellriegel cracked during the marathon and Allen slid past him and into history.

I love seeing the athletes I coach exercise restraint, and love it even more when they do so in situations where they previously wouldn’t have, demonstrating growth in this area. Recently a runner I coach sent me a message through TrainingPeaks letting me know he was feeling tempted to turn the easy 2-hour run on the calendar that day into a long tempo run and seeking my input—thumbs up or thumbs down. I replied with an emphatic thumbs down, but by then my athlete had already set out on the run. Afterward, he reported to me that he had made his own decision to restrain himself, completing the session as planned instead of running hard. I praised him fulsomely for his restraint, for I have found that rewarding restraint encourages it. If you’re self-coached, be sure to give yourself a pat on the back when you exercise restraint. Over time, such positive reinforcement will make restraint your athletic superpower.

I first discovered the work of Veronique Billat in 2002, when I was working on my book The Cutting-Edge Runner. That’s a long time ago, but in retrospect I’m somewhat embarrassed that I hadn’t known about her even earlier, as she was then already well on her way toward titan status in the field of exercise science.

If you’re seeing Billat’s name for the first time, don’t be embarrassed. It’s not the job of everyday endurance athletes to maintain an up-to-date mental Who’s Who? in the area of sports science research. Now in her late 50s, Veronique is a Frenchwoman with a half-marathon PR of 1:18 who teaches at the Interdisciplinary University of Paris and has authored well over 200 scientific papers focusing primarily on the optimization of training methods in distance running. In 2018, she published a book titled Révolution Marathon that I never heard about because it was written in French. Correction: I hadn’t heard about the book until recently, when Johnathan Edwards, who is studying for his PhD under Billat, emailed me to ask if I would be willing to review an English version of it that he’s working on.

The answer was yes, of course, and within 24 hours I had a digital copy of the manuscript on my laptop. I’m not sure exactly what I expected, but The Science of the Marathon, as Edwards has rechristened the book, isn’t it—in a good way. Billat’s thesis is simple: The most effective way to run a marathon is not at the steady pace that is commonly advocated but at a variable pace, and by extension, marathon training should emphasize variable-pace running instead of being dominated by steady-pace running as it is for so many runners.

Billat makes a compelling case for this approach, beginning with the observation that the fastest marathons are run at variable speeds, and most often feature a fast start, a slower but oscillating middle, and a fast finish. She concedes that some of the underlying physiology that makes the variable-pace approach effective for the best marathoners in the world is absent in slower runners, but contends that a version of the same strategy is best for us mortals as well.

Why? A few reasons. First, Billat argues, starting fast allows a runner to get ahead of their goal time without putting themselves in a hole that they can’t climb out of, provided they slow down after 2 km (1.2 miles) or so. A fast start also primes the body and mind in ways that make the slower running that follows easier. Additionally, by generating high levels of lactate, starting fast creates a biochemical milieu in the muscles that stabilizes pH, preventing fatigue and making subsequent accelerations possible.

Furthermore, oscillations in pace allow runners to utilize more of their physiological toolkit than is possible when they lock into goal pace. They can, in a manner of speaking, rest one metabolic engine while firing another, generating a lot of lactate during surges and burning that lactate during slower segments. Managed properly, fluctuations in speed enable the marathoner to maintain a consistently comfortable effort level that all but ensures they are able to make a hard push in the final kilometers. I must confess, whereas some of the physiology Billat gets into flies over my head, this last rationale makes a ton of sense to me, as I know from studying Samuele Marcora’s psychobiological model of endurance performance that running performance is ultimately determined by perceived effort, and I know from personal experience that if you keep your pace steady in a marathon, your perceived effort level will fluctuate, and if you run by feel, your pace will fluctuate. As Billat puts it, by taking her approach, “You will no longer run to maintain a speed but rather run to maintain a feeling of racing intensity consistent with an ‘average’ effort on the marathon.”

The book mentions a 2006 study by Billat which showed that pacing by feel, hence variably, is more effective than steady pacing even at shorter distances. Subjects completed a 10K time trial by feel, and all of them exhibited fluctuations in pace. Later, the subjects were asked to complete a second 10K time trial running steadily at their average pace from the first. Amazingly, few of them were able to hold this pace longer than 7K.

It so happens that, when Edwards sent me Billat’s book, I was about six weeks away from taking a crack at running a 2:38 solo marathon time trial. My plan was to run 26.2 consecutive 6:04 miles. I am now considering the possibility of replacing my usual pacing strategy with a variable-speed approach. Having completed well over 40 marathons, I have some opinions of my own about how best to train for and execute a race of this distance, and I don’t intend to completely abandon my formula in favor of Billat’s. For example, she takes a dim view of high-volume training, whereas I know beyond the shadow of a doubt that high volume is critical to maximum marathon performance for me. But I have found her argument convincing enough to tweak my training according to Billat’s recommendations to prepare for this style of time trialing.

My first test was a 13.11-mile marathon-pace run, which again, I would normally have attempted to run at 6:04 per mile from start to finish. Instead I aimed to start with a pair of 5:52 miles, then run seven 6:10 miles, and finish with a cutdown from 6:02 to 5:56 over the closing four miles. In a word, it did not go well. After completing the first two miles in 5:49 and 5:51, feeling pretty comfortable, I slowed down to 6:10 pace expecting it to feel like an utter cakewalk, but it didn’t, and indeed I never really settled in at that slower pace. I was only able to cut down to 5:59 for the last mile, and doing so required a near-maximal effort (though I was slightly ahead of my target by then and wound up completing the run with an average pace of 6:03.5 per mile.

I’m smart enough not to conclude from this one experience that Billat’s variable-pace strategy doesn’t work, though at the same time I most certainly can’t conclude that it will work for me. Here’s the rest of my After Action Report on the test:

It was a hot day and I didn’t have my best legs going into the run. It’s possible I would have struggled even if I had used my usual steady pacing approach.

I’ve spent a lifetime making steady pacing second nature for myself. It’s not surprising, therefore, that the variable-speed strategy was a shock to my system. In the next test I will know better than to expect the slower running that follows the fast start to feel absurdly easy. I’ve done enough reading in exercise science to know that perceived effort is highly influenced by expectations. A relatively easy effort will feel harder if you expected it to feel easier.

Though Billat herself would probably disagree, at 49 I think I might just be too old to use the variable-speed approach effectively. In her book Billat points out that her strategy requires a large speed reserve. Her rule of thumb is that your maximum running speed must be at least double your marathon speed; otherwise the fast start and later surges will crush you. I’ve been working pretty hard on my speed lately because I’ve been participating in virtual mile races, so I’m already doing what I can to maximize my speed reserve, but it’s obvious that age has stripped me of my highest gears and they’re not coming back.

Be that as it may, I am at a point in my athletic career where nothing really matters all that much and I’m willing to take chances I would not have taken when I was younger. So I fully intend to continue guinea pigging Veroniqe Billat’s variable-speed marathon pacing strategy, and I’m confident it will be fun and interesting at the very least. More to come.

If you ask the average running coach what good running form is, he or she will probably answer with phrases like “midfoot strike,” “high stride rate,” and “low vertical oscillation.” It is true that these and other form characteristics are common in top runners and less common in slower runners. But there are exceptions. Meb Keflezighi won the 2009 New York City Marathon as a heel striker, Ryan Hall set an American record of 59:43 in the half marathon with an unusually bouncy stride, and Mo Farah won 10 Olympic and World Championships gold medals with an exceptionally low stride rate.

The Basis of a Good Running Form

On the basis of the fact that no two champion runners run the same way, I would argue that no specific movement pattern defines good running form. What, then, is the true essence of good running form? One possibility is efficiency. This idea has a lot going for it. After all, what is it that you really want your running form to do as distance runner? Not maximize power–that’s for sprinters. Rather, you want your running form to minimize the energy cost of running so you can go faster and farther before you become exhausted. It doesn’t matter how you minimize the energy cost of running, biomechanically, but only that you minimize the energy cost of running. Obviously, some movement patterns are generally more efficient than others, which is why most of the best runners are midfoot strikers. Nevertheless, each body is unique, so we shouldn’t expect every runner to minimize energy cost in the same way.

As sensible as it seems to define good running form as that which maximizes movement economy in an individual runner, however, I think this definition misses the mark as well. The true definition of good running form, I believe, is the particular way of running that feels easiest to an individual runner. I can’t claim to have come up with this theory. I got it from Samuele Marcora, father of the psychobiological model of endurance performance. Here’s an excerpt from an email message Marcora wrote to me about his perception-based theory of biomechanics:

“Many specialists in this area. . . still think that the [central nervous system] controls locomotion to optimise energy. They envisage an optimal solution in which the CNS senses energy expenditure and adjusts locomotion parameters (e.g., step frequency) to minimise energy expenditure. There are some basic neurophysiological problems with this proposal. However, the biggest problem is that there are several instances in which the CNS chooses locomotion parameters that optimise perception of effort at the expenses of energy expenditure (e.g., walking to running transition). When energy seems ‘optimised’ this coincides with the optimal perception of effort as well. So perception is always optimised but energy expenditure is often not. The. . . conclusion is that the CNS optimises perception of effort rather than energy expenditure.”

Energy expenditure and perceived effort are closely linked. For the most part, movement patterns that reduce energy expenditure also make running feel easier. It is very likely that the evolutionary reason individual runners adopt the particular way of running they do is to minimize energy expenditure. But it is perceived effort that actually controls this process. In other words, running in the way that minimizes perceived effort is the means by which runners achieve the end of minimizing energy expenditure.

Consider what happens when you’re running along and you turn into a strong headwind. You hunch forward, don’t you? This natural adjustment reduces the surface area of your body and minimizes the energy cost of running into the wind. But the choice to hunch is made consciously, and what you are really doing as a living organism is trying to make running feel as easy as possible despite the headwind. What Marcora and I are suggesting is that this is what runners are doing all the time, although mostly in subtler ways not involving headwinds.

Perception of effort is tied to brain activity. In crude terms, the harder you have to think about your movements, the harder those movements feel. So your goal as a runner is to run as thoughtlessly and unconsciously as possible. This is why consciously changing the way you run is such a bad idea. No matter what you change, you will have to think more about what you’re doing because what you’re doing is unnatural, and this will make running feel harder.

This does not mean you are stuck with your current stride forever. Every runner’s stride evolves gradually over time as the CNS learns through repetitive practice how to move in ways that feel easier (and that usually also reduce energy cost). Consider something like running with a higher stride rate. If you force yourself to run with a higher stride rate right now, running will feel harder (if only very slightly) and you will probably also be less efficient because you have to think about what you’re doing. But guess what? If you just leave your stride alone and keep training, it is probable that your stride rate will increase somewhat over time, and this natural evolution will be associated with reduced perception of effort and likely also with increased efficiency. You have to earn your stride changes.

Evidence that thinking about your running is bad for your running comes from studies in which researchers look at the effects of attentional focus on running economy. A series of experiments conducted by European researchers has shown that runners become less efficient when they focus their attention internally versus externally, even if their internal attentional focus does not involve any effort to alter their running form. Let that sink in for a minute.

I only wish these researchers had measured the effect of attentional focus on perceived effort as well, because it is perception of effort, not physiology, that directly limits endurance performance. Becoming more economical doesn’t do a runner any good if this benefit comes at the cost of increased perception of effort, as no runner can run faster than he feels he can run. And based on his understanding of what good running form really is, Marcora believes it would be a mistake for runners to try to increase their economy through interventions requiring conscious form changes (i.e., internal attentional focus, i.e., thinking), even if these interventions actually worked. “What happens to perception of effort if we make people run in the way that gets the lowest energy expenditure?” he asked in our email exchange. “I bet it would go up considerably.” And when perceived effort goes up, performance goes down, because the definition of good running form is the particular way of running that feels easiest to an individual runner.

The Basis of a Good Running Form

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