What are the Limits of Human Performance?

Reviewing the book ‘Endure’ by Alex Hutchinson

Go for a run or bike ride, and you will eventually get tired. It will become harder and harder to continue, and then you’re forced to stop. Why did you stop? This is what this book explores: what affects the limits of endurance.

It’s not a magic-bullet book on how to improve your own performance. Rather, it is a book that looks at the science of endurance training, mostly focused on running, but that applies broadly.

The first part of the book goes into the history of athletic performance and human fatigue, which was surprisingly interesting and well-done. From all the progress of sports physiology in the 20th century, there seemed to be three major factors:

• VO2max
• Running economy
• Lactate threshold.

However, the book explores a factor that seems to be more and more relevant with more modern research: your brain.

The research started in the 1990s with the scientist Tim Noakes, which seemed to suggest that the brain sets and reinforces the physical limits of endurance exercise. Now known as the “central governor” hypothesis.

The brain’s job is to keep you in a safe zone, and the brain is the one that tells you to stop. For example, the longer you exercise, the more fatigued you get. Thus the ending of your race should be the slowest. Yet, in world-class races, it’s almost exclusively the opposite — the last portion is the fastest. In these cases, the brain allows you to push further because it knows it is soon to end and the danger will no longer be relevant.

It is surprisingly difficult to know the true limits of endurance. For example, in one study, a group of elite rugby athletes, who are certainly hard-working and incredibly fit, did a cycling test at around 80% of their peak power, which made them last around 10 minutes. But after they finished, if you asked them how much power they could get in a 5s burst, they average 700 watts. Yet, their goal was to simply maintain 242 watts. So why did they stop? This is what the author tries to answer and provides a good overview of the topic.

There isn’t a decisive answer in the book. The brain certainly plays a role, but it’s unclear what role that is. There is a lot of interesting research in both ways, and experts don’t fully agree on a single model. In one way, that was a bit disappointing. The beginning of the book was so fascinating that I almost got a bit high on the psychological aspect of it. But the author made the strongest point first. But I was soon hit by necessary caveats, nuances, and limitations. It also covers more than the brain’s impact, touching on heat, nutrition, hydration, and more.

The book was delightful to read. Not only from the interesting topic it covers, but the writing is quite good as well. The fact that Hutchinson is an elite distance runner himself helped a ton. His passion for endurance is palpable and vastly enriches the narrative.

I also liked that his personal journey was embedded in the book. While it certainly covers a lot of scientific literature, it is also part of a larger narrative of his search for the limits of endurance as an athlete and as a sports journalist. If you do any type of endurance training, I’m sure this will be an enjoyable read, in addition to increasing your understanding of the limits of your own performance.

Thanks for reading. If you like non-fiction book reviews, feel free to follow me on Medium. If you don’t use Medium, you can subscribe to my Substack.