Fatigue during a race: more than just tired legs

Every runner knows that moment in a race when everything starts to feel harder.

Your legs become heavy, your pace threatens to slow down, and the battle begins. Not only with the course or the competition, but above all with yourself. Fatigue during a race is a complex interplay of physical exertion and mental processes. Anyone who thinks it's just about tired legs or exhausted muscles is missing an important piece of the puzzle: the brain.

The physical component: the engine is running at full speed

Physical fatigue occurs when the body performs intensive work for a certain period of time. The most important physical factors that play a role in this are:

• Increase in 'metabolites': During intensive running, 'waste products' or 'by-products' accumulate in the muscles, which can lead to a burning sensation and reduced muscle function.
• Energy consumption and depletion of energy reserves: The body burns carbohydrates and fats for fuel. Carbohydrate reserves (glycogen) are limited, and when they run out, energy levels drop dramatically.
• Fluid and electrolyte loss: Sweating causes you to lose fluid and salts, which affects blood circulation, muscle function, and temperature regulation.
• Increase in body temperature: Running generates heat. If your core temperature rises too high, your body activates protective mechanisms that force you to slow down.

The central governor: your brain calls the shots

According to the 'Central Governor Model', developed by researcher Tim Noakes, your brain acts as a kind of overseer during physical exertion. It continuously evaluates how hard you're working and how much reserve capacity you still have. If your brain thinks you're pushing too hard, it sends signals that make you feel fatigued—even if your muscles theoretically could do more.

This protective mechanism prevents you from pushing yourself into dangerous territory. Your brain doesn't want you to completely exhaust your energy reserves or overheat. The feeling of fatigue is therefore partly a safety mechanism, not necessarily a sign that you've reached your absolute physical limit.

The role of experience and mindset

This is where it gets interesting: experienced runners can often push through fatigue better than beginners, not because they're necessarily fitter, but because they've learned to 'negotiate' with their brain. They know the difference between discomfort and actual danger. They've learned that the feeling of fatigue at kilometer 30 doesn't mean they can't run another 12 kilometers.

Training your mental resilience is therefore just as important as physical training. By regularly putting yourself in uncomfortable situations during training—such as tempo runs or long runs—you teach your brain that you can handle more than it initially thinks.

Practical strategies to manage fatigue

1. Pacing strategy

Start conservatively. If you go out too fast, your brain registers excessive stress early on and will try to slow you down for the rest of the race. A well-thought-out pacing strategy helps you 'trick' your central governor.

2. Break the race into chunks

Don't think about the entire distance. Focus on reaching the next kilometer marker, the next aid station, or the next landmark. This makes the task less overwhelming for your brain.

3. Positive self-talk

What you tell yourself matters. Replace thoughts like "I can't do this" with "This is hard, but I've trained for this" or "One kilometer at a time."

4. Use external focus

Focus on your technique, your breathing, or your surroundings rather than how tired you feel. This can reduce the perception of effort.

5. Train mental toughness

Include workouts in your training plan where you consciously push through discomfort. For example: finish your tempo run with an extra hard kilometer, or do interval training when you're already a bit tired.

The finish line phenomenon

Ever noticed how you can often speed up in the last few hundred meters of a race, even when you felt completely exhausted moments before? That's your brain releasing the brakes. It knows the finish is near and that there's no more danger in giving everything you've got. This proves that fatigue isn't always purely physical—your brain was holding you back to protect you.

Conclusion

Fatigue during a race is a complex interaction between body and mind. Yes, your muscles work hard and your energy reserves are depleted, but your brain plays a leading role in how and when you experience fatigue. By training not only your body but also your mental resilience, you can push your limits and discover that you're often capable of more than you think. The next time you feel fatigue creeping in during a race, remember: it's not just your legs talking—it's your brain. And you can learn to negotiate with it.