Running and the Science of Mental Toughness

There is more to running than just training your muscles and improving your stamina. It is also a mental sport, and maybe even more so than previously believed.
Mental strength may in fact be the thing that separates the winners from the rest of us. Photo: Quino Al, via Unsplash
By: Mariska van Sprundel
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Motivation is a skill. It can be learned and practiced.
—Amby Burfoot, winner of the 1968 Boston Marathon

A few years ago, scientist Ashley Samson embarked on a project aimed at accessing the darkest recesses of the runner’s mind. What goes on in the minds of people who voluntarily expose themselves on a regular basis to the rigors and stress of long-distance running? Samson is attached to California State University and also runs a private clinic for athletes who wish to avail themselves of her expertise as a sports psychologist. Samson was an athlete herself in her younger years and she still runs ultramarathons, so she knows all about the mental trials of running.

This article is adapted from Mariska van Sprundel’s book “Running Smart: How Science Can Improve Your Endurance and Performance.”

Up until recently the only way to get inside the heads of long-distance runners was to ask them to fill out a questionnaire after a race. Not exactly what you would call a reliable method, as it is always uncertain how well people remember specific information after the event. Samson and her colleagues decided to try something different. They fitted 10 runners with microphones and asked them to articulate their thoughts freely and without any self-observation while out on a long run. The scientists then listened to all 18 hours of the recorded material, searching for patterns. The thinking-aloud protocol allowed only immediate thoughts to be recorded; thinking aloud actually stops the mind from wandering. Nevertheless, the scientists must have had great fun listening to the recordings. “Holy shit, I’m so wet [from all the sweat],” reported Bill. “Breathe, try to relax. Relax your neck and shoulders,” said Jenny. Bill found the going very tough: “Hill, you’re a bitch . . . it’s long and hot. God damn it . . . mother eff-er.” Fred paid more attention to his surroundings: “Is that a rabbit at the end of the road? Oh yeah, how cute.”

To cope with the pain and discomfort, the runners used a variety of mental strategies, including breathing techniques and urging themselves on.

Samson categorized the thoughts into a series of themes. Three themes in particular emerged: pace and distance; pain and discomfort; and environment. All of the participants in Samson’s experiment experienced some level of discomfort, especially at the beginning of their run. For example, they suffered from stiff legs and minor hip pain that became less severe the longer they ran. To cope with the pain and discomfort, the runners used a variety of mental strategies, including breathing techniques and urging themselves on.

There is more to running than just training your muscles and improving your stamina. It is also a mental sport, and maybe even more so than previously believed. Most runners appreciate the importance of mental strength. Those who decide to join their colleagues for a 10K run without any prior training are often able to show just how far you can get on motivation and perseverance alone. They run on “mental energy” and spur each other on. Keep going! Never mind the pain! As for ultramarathon runners, instead of ignoring pain they embrace it as part of the whole experience of long-distance running. “Pain is inevitable” is their mantra; it is an essential ingredient of the running experience. So what are the psychological qualities that make you a good runner? To what extent do they influence performance? And most importantly: Can you train mental toughness?

The Psychology of Performance

Anyone who wants to know more about the psychological side of sports would be well advised to talk to Vana Hutter. She is an expert on the mental health of top-class athletes, and she sums up all of the research on the matter as follows: Top-class athletes are armed with high levels of self-confidence, dedication, and focus, as well as the ability to concentrate and handle pressure. Their academic performance and social skills are also often better than that of nonathletic types. According to Hutter, athletes need self-regulation in order to perform. Everyone can learn, to some extent at least, to control their emotions, thoughts, and actions. And it is this aspect — learning to self-regulate — that is of particular interest to runners.

Funnily enough, Hutter began her scientific career at the “hardcore” end of exercise physiology: physical measurements of athletes’ bodies. “As time went on, however, I realized that athletic performance is determined by a combination of body and mind,” she tells me over coffee in Amsterdam. “I discovered that it is far more difficult to predict athletic performance than some physiologists would have you believe. There are so many factors that we just can’t account for.” For example, how do you explain the fact that the times athletes run are so different despite their being physically very similar?

If you were to subject the top 10 marathon runners to a physiological examination, they would probably all have a high VO₂max and excellent running economy. Some top athletes have something extra as well, however. “Measured over a longer period, the trainability of athletes is more or less the same. What really matters during competition is the extent to which their physiological systems are primed and ready to go, and how well those systems cooperate with each other,” explains Hutter. “Whether an athlete can avail of their maximum physical potential at the crucial moment is partly a mental matter.”

“You need to actively seek out situations in which you are forced to confront your own thoughts and emotions. That has the most effect.”

She provides an example. “If your muscles are a little bit more tense because you are nervous, this will have an effect on your movement efficiency. You will need more energy to achieve the same kind of forward motion. This is the biomechanical explanation of the role of psychology in performance. On the other side of the spectrum, nervous anxiety can result in negative thoughts and fear of failure.” In other words, to go far as an athlete you need not only the right kind of physique but also to be mentally strong, primarily because of the influence the psyche has on how the physical body performs. Mental strength may in fact be the thing that separates the winners from the rest of us. Today, no one denies the role played by psychology in athletic performance. However, the extent to which coaches address mental toughness when training their athletes is a different matter, according to Hutter. Most of them do integrate it in their training, but opinions vary greatly on just how trainable mental toughness actually is.


What makes you “mentally tough”? What does it require you to do? Or indeed not to do? Sports psychologists still haven’t come up with a clear answer. Mental toughness is a catch-all term without any well-defined meaning, explains Hutter. “We associate mental toughness with the ability to deal with difficult situations. And it helps if you are armed with a wide range of coping mechanisms, as well as the creativity required to turn difficult situations to your advantage.” In any event, one thing you really need in order to train and perform well is self-regulation. Perseverance, the ability to block out your surroundings, clear goals, and being able to cope with stress are the skills associated with self-regulation.

There are two of kinds of self-regulation, and they are often used interchangeably in scientific literature. The first is self-regulated learning, which is important in every kind of sport. It involves taking control of your own development process and using every available opportunity and situation to keep on improving, for example by tackling the steep hill instead of sticking to the flat track or going to training after a hard day’s work or a bad night’s sleep.

The second kind of self-regulation concerns how to control your emotions, thoughts, and actions and keep them in line with your goals. For example, how do you deal with the inevitable nerves before a race and feelings of boredom and fatigue while you are running? “Some people have a natural talent for self-regulation,” says Hutter. “Even children can be very good at it from a young age.” She cannot say for sure, however, whether top-class athletes are born with an inherent talent for self-regulation or develop it from practicing their sport. “Self-regulation can be learned to some extent, but we do not know how trainable it is, primarily because of its complexity. I think there’s a limit to its trainability. People who are very bad at it can certainly improve. But they will probably never be as good as those who have a natural talent for self-regulation or have worked on it from an early age.”

So how should recreational athletes train their self-regulation? Should they employ a coach or sports psychologist? Sure, a sports psychologist can help, but a little background information is usually enough to get you started, Hutter tells me. “You need to actively seek out situations in which you are forced to confront your own thoughts and emotions. That has the most effect.” We may not always realize it, but every time we train we are exposed to a lot of different psychological stimulants. “We all require motivation to complete a training session. Sometimes you have to dig very deep to find it, and sometimes it’s there at your fingertips. Increasing your pace and pushing on through the fatigue is a form of mental power training. Even just making time for an endurance training session lasting a couple of hours involves a psychological process.”

The Mystery Behind Stopping

There are of course limits to human athletic ability, regardless of how well trained you are or how many mental strategies you have at your disposal. Although it differs for each individual runner, eventually we all reach a point where we have to give up. Within the realm of sports science, physiologists and psychologists are all looking for the answer to the question: What causes us to stop or slow down during a race? After all, at the moment when we stop we usually still have enough energy in the tank. The decision to stop running has nothing to do with your muscles or energy system and everything to do with your brain. Experts are in unanimous agreement that it is the brain that controls physical exercise. However, they are still arguing about how it persuades us to stop before we reach the point of complete exhaustion. Does the brain act on signals from the body, or is it our psyche that pulls the strings? The question has given rise to a fascinating theoretical discussion.

Mind over muscle? Limits to Endurance Performance | Professor Samuele Marcora | Think Kent
Samuele Marcora believes that the reasons for fatigue while running are of a purely psychological nature.

One of the liveliest contributors to that discussion is Samuele Marcora at Kent University in England. He believes that the reasons for fatigue while running are of a purely psychological nature. His research suggests that signals from the muscles, heart, and lungs do not play a significant role in the decision to stop or slow down. Psychological factors, however, such as mental tiredness after a day spent staring at a computer, do have a direct effect on the decision to stop. Marcora is one of the best-known scientists studying the perception of exercise among endurance athletes. In his opinion, what runners refer to as exhaustion has nothing to do with their physical ability to carry on or not. It is simply a matter of deciding to give up.

Marcora’s official title is Professor of Exercise Physiology, but he feels more of an affinity with psychology than with physiology. Sport and exercise are goal-oriented behaviors that are fueled by motivation. And, as he explains, the branch of science that studies behavior is not physiology but psychology. I attended a lecture given by Marcora at Radboud University, where he explained his concept of fatigue. Afterward we sat down for a chat at a picnic table on the university campus.

The focus of his research is on fatigue in endurance sports. Marcora is trying to establish why humans are unable to maintain a certain speed or level of strength indefinitely. What causes us to slow down, sometimes even to walking pace, during a race? “Up until very recently it was assumed that a person could continue exercising until they reached the point where their body was unable to transport enough oxygen to the muscles,” Marcora tells me. “In that case, the muscles are no longer able to generate the required power quickly enough. They are just too tired.” The generally accepted theory was that the body always reaches a point at which it has to stop, regardless of how motivated you are. However, there has never been any convincing data to support that model. Marcora believes that we rarely reach the point of physical exhaustion while running. The results of his own research contradict the idea that we stop running as soon as we receive certain signals from our body.

In 2010, Marcora and his colleague Walter Staiano invited 10 male athletes to their lab for an endurance test in which they were asked to pedal for as long as possible on a bicycle ergometer set to a certain level of resistance. Before the test started, Marcora and Staiano asked each athlete to pedal as hard as they could for just five seconds. A record was kept of the power generated by their leg muscles. After this short, explosive test the men were asked to cycle for as long as possible until they couldn’t carry on. The average time was 12 minutes. It was the final part of the test that proved the most interesting. After the endurance test the scientists asked the athletes to repeat the five-second explosive burst of cycling.

“When someone stops because they are exhausted, they still have plenty of energy left over.”

Just picture it: You are completely exhausted but you are asked to cycle like a madman again. Surely your legs would refuse. Nothing of the kind, as it turned out. The men did not score as well in the second explosive test as they had the first time around, but they were still able to generate three times more power than they had during the longer endurance test. Isn’t that strange? First you give up because you can’t pedal on anymore, only to deliver another explosion of power immediately afterward. This means that tired muscles and a lack of energy are not the problem, according to Marcora and Staiano. So what caused the cyclists to give up? Motivation, or rather the lack thereof, they suggest. The participants knew that the last test would only take five seconds and so were able to come up with the goods. The endurance test, on the other hand, lasted much longer, without the athletes knowing precisely how long they would have to keep pedaling. This is probably what caused them to lose their motivation. “When someone stops because they are exhausted, they still have plenty of energy left over,” says Marcora.

It’s a different story for more explosive sports, however. In the case of weight-training, there is a point past which your body cannot go on. After a certain number of push-ups, your muscles simply cannot generate enough power to continue. Instead, your arms begin to tremble and you collapse to the floor. Kevin Thomas and his colleagues at Northumbria University in England conducted an experiment with cyclists in which they demonstrated that the shorter the period of physical exertion, the more exhausted the muscles become. And the longer the period, the more tired the brain becomes. So in the case of short, intensive exercises, the legs suffer the most, while longer endurance exercises tend to exhaust the brain.

Mind Over Muscle

In 2012, the renowned South African sports scientist Tim Noakes also questioned the idea that burning muscles are the dominant factor when it comes to our ability to carry on. He believes that our brain houses a kind of subconscious command center (which he calls the “central governor”) that protects our body from damage like extreme exhaustion or torn muscles. This command center monitors the incoming signals from our body, such as the level of metabolites in the muscles and the body’s supply of sugar. If the risk of damage is acceptable, we can carry on running. However, the command center always pulls the plug and tells us to stop long before we’ve used up our energy supply. Noakes believes that its job is to ensure that we never go beyond our physical limits and do real harm to ourselves in the process.

The central governor theory is well known among scientists, but Marcora is not a fan. He believes that it assigns too important a role to the signals received from the muscles, heart, and lungs. But how does our brain make us stop if it doesn’t make use of the signals coming from our muscles? “I am not saying that what happens in the body is of no consequence,” he says. “But the all-important factor in the case of endurance sports is perception of effort.”

“Perception of effort” is a subjective feeling that one might express as “Oh boy, this is tough going.” Runners constantly try to find the right balance between the maximum amount of effort they are prepared to put in to achieve their goal and the effect that effort has on them. Imagine you have set yourself the goal of running a half marathon in under two hours. For the first 90 minutes you have no problem maintaining your pace of 6.5 mph, even though the run is feeling tougher as you go along. That feeling continues to grow stronger until you reach a point where you are so exhausted that you cannot carry on. The feeling of exhaustion is greater than the amount of effort you are prepared to put in. The result? You slow down. In fact, you might even throw in the towel and walk the rest of the way.

“If you run at the same pace for a long period of time, the perception of effort increases as you go along,” continues Marcora. “It feels increasingly harder to keep on running, even though your muscles are providing the same amount of power at the same speed on a continuous basis. At a certain moment, however, the perception of effort reaches a maximum value that forces the athlete to stop. Even the most motivated athletes have to give up at this point, the point of exhaustion. And that’s the kind of ‘fatigue’ I’m interested in.”

Mental Fatigue

Marcora and his colleagues carried out an experiment in 2009 in an attempt to prove that the perception of effort is what causes us to stop exercising. Sixteen participants were invited to their lab, where they first filled out a questionnaire related to their mood at that moment. They were then asked to sit in a dark room, where one group of participants was given a difficult computer assignment that lasted ninety minutes. A computer assignment requires cognitive activity and therefore taxes the brain; it makes you mentally tired. The other group — the control group — was told to watch a documentary about cars and trains; they experienced no mental fatigue. When they emerged from the darkened room the participants were once again asked to fill out a questionnaire describing their mood, and to answer an extra question related to their motivation for the next part of the experiment: a cycling test.

The men and women taking the test were instructed to sit on a bicycle ergometer and were fitted with a mask to measure their respiratory gas exchange and electrodes to monitor the heart. They were then told to pedal as fast as they could until they could pedal no more, with the resistance being increased every two minutes. To provide extra motivation, there was a prize of $50 on offer for the cyclist who could last the longest. During the test, research assistants asked the cyclists at regular intervals to rate their perception of effort on a scale of one to 15. “The only way to measure perception of effort is to ask people to gauge the effort demanded of them,” according to Marcora. After the cycling test, the participants filled out the mood questionnaire for the third time. Everyone was asked to return to the lab for a second session in which the participants who had watched the documentary were given the computer assignment instead, and vice versa.

The participants who were mentally fatigued reached the maximum level of effort they were prepared to put in much quicker before quitting.

The difference was crystal clear. The test subjects who had to apply their cognitive powers during the computer assignment caved in more quickly during the subsequent cycling test. They also rated the difficulty of pedaling on a lot higher than the control group. The funny thing is, it had nothing to do with their heart, lungs, or muscles, which continued to function perfectly according to the data from the mask and electrodes. Furthermore, the computer assignment had no effect on the level of lactate in the blood, and the VO₂max was more or less the same for both groups.

Where the groups did differ was in the levels of mental fatigue. The results of the questionnaire revealed that the brains of those tasked with the computer assignment were a lot more tired before they took the cycling test. However, they were not less motivated. While the cycling test became progressively more difficult for both groups, the participants who were mentally fatigued reached the maximum level of effort they were prepared to put in much quicker before quitting. Conclusion: a cognitive computer assignment has no effect on your muscles, but is does exhaust you mentally, which in turn has a negative effect on your endurance performance. Mental fatigue increases the perception of effort, that is, your perception of how hard it is to keep going. In 2017, a group of scientists published an overview in the journal Sports Medicine of the studies carried out into mental fatigue, all of which suggested that mental fatigue has a negative effect on endurance performance. So it appears that if you are mentally fatigued, you are likely to throw in the towel a lot sooner.

Mental Training

It’s 7 a.m. on Monday morning and my alarm has just gone off. I don’t feel like getting up. I had a late one last night and I’m still tired. But up I get, casting a jealous look at my boyfriend as he turns over for another hour’s sleep. He doesn’t have a 10-kilometer run on his schedule before the working day begins. I gobble down a banana before heading out the door. After only three kilometers I’m already beat; it feels really tough today! My legs are refusing to cooperate, I’m gasping for breath, and all I can think of is the string of kilometers I still have ahead of me. Then it starts to rain. And yet these are precisely the conditions I was hoping for, because I know that we can train our brain to get used to feelings of fatigue.

Brain training is not unlike regular training. When you start running for the first time, your legs soon grow tired and you are quickly out of breath. The more you train, however, the more your body adjusts: tendons, bones, and muscles all become stronger and your stamina increases. To make your brain stronger you need to do some tough mental training, like going for a run after a hard day at work. This helps you to delay the point at which running begins to feel really tough. It’s all about developing the kind of mental resilience that comes from going out for a run even when you really don’t feel like it. Luckily there is no shortage of potential tough-going scenarios, including setting your alarm for an early morning jog after a night out on the town.

If there is one thing that shatters you mentally, it has to be too little sleep. Even just one bad night’s sleep is enough to undermine your performance, because the effort you have to put in feels much heavier. This probably explains why the top Belgian swimmer Pieter Timmers had his own mattress flown to the Olympic Games in Rio de Janeiro in 2016. His performance at the European Championships a few months earlier had been disappointing, and he attributed this to sleeping poorly.

Brace Yourself

There are lots of psychological tricks that can have a direct effect on the perception of effort. Using music to trick the mind into believing that you are less exhausted than you actually are during a workout is one. Setting clear goals can also be a great motivator. Knowing how long a course is and how much ground you have already covered makes running a lot easier than when you are ignorant of these facts. Verbal encouragement from people along the route also makes life easier for the runner, as does previous experience with a specific race or forms of exercise. Another good trick is simply to brace yourself: If you expect this to be your hardest race ever, it will probably turn out easier than you thought in the end.

If you have tried every trick in the book and are still unable to maintain your pace, there is one last possibility you can resort to: Instead of endeavoring to achieve the time you had set for yourself, you can try to slow your fellow runners down. Not by literally tripping them up, but by using a little psychology. Our brains are very receptive to facial expressions; we try to read them to judge a person’s mood. When we unconsciously notice a happy face, it reduces our perception of effort, according to the results of experiments carried out by Marcora. An angry face does exactly the opposite. So if you want to slow your competitors down, wear a T-shirt with a cross face on the back. Just kidding, recreational runners aren’t that mean-spirited. We tend to compete only with ourselves.

Research into the psychological side of running has resulted in many new and beneficial insights. It goes without saying that you need an excellent set of physical skills and qualities to become a great athlete. But without the mental equivalent, no runner can ever fulfill their potential. Mental toughness and psychological skills are much more important to your ability to keep going than was previously thought. And you can learn to persevere too, as long as you get enough practice. Of course, it is your physical fitness that ultimately determines the extent to which you can teach your brain to keep on running. Someone who has difficulty completing a 5K will not be ready to run a marathon after a few weeks of intensive brain training. But the 5K will start to feel a lot easier.

My closing advice: Train your brain to combat fatigue. Go for a run after a long day at work or a bad night’s sleep. If you are about to enter a race, avoid all strenuous mental tasks beforehand and set yourself an ambitious but realistic goal, one that will motivate you. If you like to listen to music while running, pick songs whose rhythm will match your stride frequency. Your mind is a powerful tool to improve running performance. Raising your mental game is not something you do overnight, but it can be learned and practiced.

Mariska van Sprundel is a freelance science journalist who has written for Runner’s World and other publications. She is the creator of The Rational Runner, a blog about science and running, a running instructor for recreational runners at a Utrecht athletics club, and the author of “Running Smart,” from which this article is adapted.

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