Sports Performance: How Far Can Your Brain Push Your Limits?

When your body is ready but your mind doesn’t follow

As a teenager, I competed in aerobics, a sport of rare intensity: a routine lasts barely two minutes, yet from the very first one, you are already beyond your limits.

I trained a great deal, my muscles responded, my sequences were polished, and I genuinely felt that everything was working.

And yet, on competition day, there was always a moment when something went wrong. Fear crept in, other people’s eyes weighed on me, and my body stopped doing what I knew it could do. In all the competitions I took part in, I managed my mental state only once, and at the time, I didn’t understand why: I knew nothing about my brain yet.

You may have experienced something similar: serious preparation, a body that was ready, and on the day itself, a performance below what you knew you were capable of. So why aren’t our physical abilities always enough to express our full potential?

Why can mental fatigue limit physical performance?

We often think of effort as a matter of muscles, breath and cardio. That overlooks the fact that during a run or a tough training session, your brain is working nonstop: it monitors your sensations, manages your pace, makes decisions and keeps your doubts in check.

So what happens when it arrives at the effort already tired, say after a long day of concentration?

Researchers have tested this very concretely. In 2009, Samuele Marcora and his team asked 16 people to cycle to exhaustion on two occasions: once after 90 minutes of a demanding concentration task, and once after 90 minutes of watching a documentary.

After the concentration task, participants gave up about 15% sooner.

But the most surprising finding lies elsewhere. Their heart, breathing and muscles responded in the same way in both cases. Only one thing changed: the effort felt harder throughout the exercise, so they reached the point where they couldn’t go on more quickly.

In other words, their bodies weren’t necessarily more tired. What had changed was the way they experienced the effort.

This experiment, carried out on a small group, is a reminder of something simple: your brain arrives at the effort carrying everything it has been through that day. That’s one more reason to take recharging a tired brain seriously.

How does your brain interpret your body’s limits?

A brain that seeks to protect you first

During a long effort, your body constantly sends you signals: your breath getting shorter, your legs growing heavy, the heat rising.

Your brain doesn’t just receive these signals. It interprets them.

And it does so with a well-known tendency, the negativity bias. We are the descendants of those who survived, in other words, of those who spotted danger fastest. Our brain has inherited that vigilance, and it still gives priority to whatever might go wrong.

This isn’t a personal flaw; it’s a form of protection. I explain this in more detail in an article on what your negative thoughts are trying to protect.

The downside is that your brain can interpret discomfort as a threat. The urge to stop can then arrive long before your body has actually reached its limits.

Expected discomfort or a genuine warning sign?

The whole challenge is to tell the difference between what is unpleasant and what is dangerous.

Breathlessness on a climb, legs burning in the final kilometers, the urge to slow down: that is the expected discomfort of a demanding effort. It’s part of the journey.

Unusual pain, feeling faint, or an exhaustion unlike anything you’ve known, on the other hand, are signals to listen to, not to push through.

How do your thoughts shape the way you experience effort?

During effort, there is what your body feels, and there is what you tell yourself: “I’m not going to make it,” “I’m already spent,” “The others are stronger than me.” These phrases are far from harmless. They color the way you experience every sensation, and they can turn a passing difficulty into giving up.

I often think of Tony Parker’s story. Early in his career, if he missed his first three shots, one thought would take over: he wasn’t going to make it. And sometimes, the whole game would turn.

He eventually adopted a very simple technique, shared with him by another basketball player. When that thought came, he would speak directly to his brain and tell it: “delete.” A way of deliberately restarting his thinking, the way you reboot a computer.

Of course, an anecdote isn’t scientific proof. But it illustrates what metacognition makes possible: the ability to observe your thoughts, then choose whether or not to follow them.

It isn’t about fighting your brain, because fighting a thought often gives it even more room. It’s about noticing it and letting it pass, as if you were telling it: “I’ve seen you, but I don’t need you.”

Learning to observe your thoughts rather than be ruled by them already changes the way you experience effort.

The problem isn’t having fears or doubts. The problem is not knowing what to do when they show up.

Can you train your mind to cope better with fatigue?

I like to compare focus to a muscle. It’s an image, not an anatomical description, but it captures something true: what you use regularly becomes more available on the day you need it.

And it isn’t just an image. In 2014, Anthony Blanchfield and his colleagues, including Samuele Marcora, set out to see whether this perception of effort could be influenced by working on one’s inner dialogue.

They divided 24 cyclists into two groups. For two weeks, the first group trained to use encouraging phrases, chosen in advance, during exercise. The second group changed nothing in its habits.

In the final test, cyclists in the first group lasted about 18% longer, and the effort felt less strenuous to them. In the other group, nothing had changed.

In this study, then, two weeks were enough to change the way effort was experienced. That is exactly the role of the anchor phrases I often talk about, and it echoes an idea I’ve long championed:

Mental strategy can’t be improvised on the day. It is trained, just like the body.

What strategies help you get through the hardest moments?

This is one of the topics I discussed at length with Guillaume Klein on the Ultra Endurance Podcast. When I want to know whether an athlete has already worked on their mental game, I look at one thing only: do they have a strategy?

Without a strategy, they remain exposed to fear, pressure, other people’s eyes and discomfort, just like anyone else. That is the whole point of mental preparation: being equipped for those moments, rather than hoping they never come.

Here are the tools I shared on the podcast, grouped into three stages.

1. Prepare mentally for difficulties

We often associate visualization with the image of victory. I recommend also visualizing the moments when things could go wrong, such as a slump or a pain that sets in, and preparing a plan A, a plan B and a plan C for each one.

The aim isn’t to dwell on the worst, but to imagine it in order to respond better. I experienced this myself during a neurofeedback study: staying on negative images for too long ends up creating a negative state. So you visualize the difficulty, and above all your response to it.

And as I pointed out on the Extraterrien podcast, visualization never replaces training: you don’t become an athlete in your head alone.

Anticipate the obstacle rather than hope to avoid it.

Example: “If I stall on the last climb, I slow down, I breathe, and I aim for the next bend.”

2. Guide your attention and move forward step by step

When the finish line seems out of reach, you shorten the horizon with very short goals, such as “just five more minutes.” An anchor phrase, prepared in advance and repeated, also helps the brain regain clarity when emotions run high: that is exactly what the cyclists in the study above did.

I also recommend practicing, during training sessions, the deliberate shift from one point of attention to another: your thoughts, the landscape, your sensations. Together with heart coherence breathing, practiced twice a day, these habits become reflexes, available on the day the event leaves you no strength to think about them.

When the effort becomes too great, shorten the horizon and redirect your attention.

Example: “Five more minutes. I look at the landscape, then come back to my breathing.”

3. Draw on your resources and regain flexibility

I like to offer a simple framework: three energies to mobilize actively. Physical energy, through food and sleep. Emotional energy, when you reconnect with a positive memory or a person you love. And cognitive energy, through your short-term goals and anchor phrases.

In long events, fatigue is inevitable. The goal isn’t to avoid it, but to learn to perform with it, by recognizing your warning signs: a break taken at the right time is an investment, not a waste of time.

Finally, cultivate a playful mindset. We rarely talk about “playing” when we run, and yet creating your own rules, leveling up or exchanging a smile with another runner can unlock unexpected resources. Curiosity and enjoyment have their full place in your performance state.

Know where to draw your energy from, and accept a break when it’s needed.

Example: “I think of the person waiting for me at the finish, and I set myself a challenge: catch the runner in the blue shirt before the bridge.”

What can sport teach us about everyday challenges?

You may not be an athlete. But your days sometimes look like endurance events, with back-to-back meetings, projects that last for months and decisions to make in the evening, when your energy is at its lowest.

The studies cited in this article focus on sports endurance: they don’t tell us what happens in your office. But some questions arise in the same way.

What are your own signs of fatigue? What do you tell yourself when a project drags on? Do you have a strategy for the moments when everything feels heavier?

As I explained on the Ultra Endurance Podcast, fatigue often pushes us toward the easiest decision rather than the right one. Recognizing that moment gives you the choice to take a break before deciding.

And just as I suggest to athletes, after a difficult day, start by asking yourself what went well. Then choose one or two points to improve, no more.

It’s not the absence of fatigue that makes the difference. It’s what you know how to do when it shows up.

Pushing your limits also means learning to recognize them

I often think back to my aerobics competitions.

What I lacked wasn’t physical training. It was a strategy for the big day: knowing what was happening inside me, and what to do with it. Today, I know that this strategy can be learned.

Pushing your limits doesn’t mean always going further, at any cost. It means better understanding what your body is telling you, what your brain does with it, and choosing consciously: keep going, adjust or recover.

Sometimes, progress means holding on for five more minutes. Sometimes, it means knowing when to stop.

This dialogue between body and brain is what my husband Ayo, a former high-level athlete, and I explore on stage in our Science & Sport keynote.

Sources

Todorova, B. Interview with Guillaume Klein, Ultra Endurance Podcast, episode 58: neuroscience and ultra-endurance (podcast, in French).

Todorova, B. Interview for the Extraterrien podcast, Ce que votre cerveau vous cache sur votre potentiel (YouTube video, in French).

Marcora, S. M., Staiano, W., & Manning, V. (2009). Mental fatigue impairs physical performance in humans. Journal of Applied Physiology, 106(3), 857-864.

Blanchfield, A. W., Hardy, J., De Morree, H. M., Staiano, W., & Marcora, S. M. (2014). Talking yourself out of exhaustion: the effects of self-talk on endurance performance. Medicine & Science in Sports & Exercise, 46(5), 998-1007.