Alex Hutchinson (@sweatscience) is a National Magazine Award-winning science journalist who writes about the limits of human performance for Outside, The New York Times, The New Yorker and other publications. His most recent book is the New York Times bestseller Endure: Mind, Body, and the Curiously Elastic Limits of Human Performance. Prior to becoming a journalist, he worked as a postdoctoral physicist for the National Security Agency and competed as a long-distance runner for the Canadian national team. He lives in Toronto. In this interview, Alex and I discuss the mental and physical training tactics of top endurance athletes and how they might apply to other aspects of life.

Greg: You’re a former national team distance runner. Was there a moment in your athletic career where you realized you were cultivating a trait that would spawn an entire book?

Alex: I wasn’t really thinking about it that way at the time, to be honest. I was definitely a student of the sport, trying to understand the factors that made me good and the factors that held me back. And I was aware—as I think most athletes are—that simple variables like VO2max can’t fully explain who wins and who loses. But I had no idea that there were scientists who were trying to delve into these deeper questions. It was only later, when I started writing about sports science as a journalist, that I started to look at my athletic career and unpack some of my experiences. I realized that there were a few moments—key races, unexplained breakthroughs—that had seeded my curiosity about the nature of limits.

For example, my big goal in college was to break the four-minute barrier for 1,500 meters (the equivalent of a mile in roughly 4:18). But I hit a plateau for three years or four years, running 4:01 or 4:02 over and over. My big breakthrough came when the timekeeper in a race gave me the wrong mid-race splits by about three seconds, leading me to believe I was running three seconds faster than I really was. This somehow managed to trick me into thinking I was having an amazing day, and I ended up running 3:52—a huge breakthrough. After that race, it was as if something clicked in my mind, and I went on to run 3:49 and 3:44 in my next attempts at the distance. It was hard to explain that sudden change based simply on my training or my VO2max.

Greg: In Endure, you describe the balance between overcoming mental blocks and physical discomfort to achieve feats of endurance. What’s the biggest lesson on the mental and physical side you learned during your research?

Alex: My natural inclination is to be very skeptical, and not trust anything I can’t see and measure. So I’ve always put a lot of emphasis on the physical side of endurance. If you’re racing and it feels painful, that must be because you’re experiencing some form of physiological stress, and if you can train to reduce that physiological stress you’ll be able to go faster.

The big shift for me in researching this book was realizing that there isn’t a simple one-to-one correspondence between the physiological stress you’re experiencing (lactate in the muscles, say) and the discomfort you experience. The physiological side is real, of course—but how you experience it also depends on other factors like your expectations and background thoughts. That means there’s a mental side to performance that you can actually measure and observe in the lab, which to me is a game-changer.

When it comes to endurance, we’re not all born equal—but very few of us come close to reaching our genetic limits.

Greg: How much of the capacity to endure is genetic and how much can be trained? I’m pretty sure I’ll never run a 2:10 marathon, but how much could I be leaving on the table by not training properly?

Alex: That’s a tough question to answer, and (cop-out alert) it really depends on the context. When we talk about the truly elite levels of performance, like a 2:10 marathon or qualifying for the Olympics, having the “right” genetics is crucial. If you were to randomly select 1,000 babies born around the world on a given day and forcibly devote their lives to training to become elite marathoners (I know, it sounds horrible), I doubt more than a handful (less than ten?) would reach that threshold.

But if you move the goalposts a bit and ask how many people have the innate genetic potential to, say, qualify for the Boston Marathon (which in the fastest categories requires somewhere around a 3:00 marathon), then the answer changes. Qualifying for Boston is hard, but in reality, virtually no one on the planet actually invests the time and effort to truly find out if they’re capable of it. Spend ten years being active and building enough base to be able to train hard without getting hurt, and then spend another ten years running 100 miles a week including a couple of hard interval workouts, then we’ll see who’s got the genetic potential.

Translation: when it comes to endurance, we’re not all born equal—but very few of us come close to reaching our genetic limits, so in a sense they’re irrelevant.

Greg: As part of your research, you followed the Nike project to break the two-hour marathon barrier. What was your biggest takeaway from the training you witnessed in that program?

Alex: I wrote a lot about the scientific and technical elements of the Breaking2 project, like the Vaporfly shoes and the drafting formation and so on. But in the end, what really stuck with me was Eliud Kipchoge’s mental approach. He has incredible self-confidence, and he systematically works to build that confidence. I think that’s an underappreciated key to his success, both in Breaking2 and in the world record he just set.

Kipchoge is a big reader of motivational books, and he’s very thoughtful about the links between his mindset and his performance. As he sometimes says, “I don’t run with my legs, I run with my heart and mind.” I don’t think he works with a sports psychologist or anything, but he’s actively trying to control his mental state rather than just leaving it to chance.

Greg: Does endurance translate from physical activities to other realms? If I’m training for a marathon, will some of that acquired perseverance help me in my day job? Or is it task-specific (e.g. a great marathoner may not have the mental endurance to study for a final exam)?

Alex: I think there’s enormous transfer from physical endurance to endurance in other realms. In fact, one of the conclusions I came away with after writing Endure is that there isn’t really a meaningful distinction between endurance in sports and endurance elsewhere. The definition of endurance I used (borrowing from a researcher named Samuele Marcora) is that endurance is “the struggle to continue against a mounting desire to stop.” That’s a definition that applies just about anywhere.

Now, there’s certainly some specificity too. You’re not going to ace your calculus exam just because you’re a good runner. But I think there’s broad overlap in terms of setting goals, doing the work required, staying focused, and tolerating discomfort.

Greg: How do we all find the ability to dig a little deeper and go a little farther?

Alex: If I had a simple answer, I’d be selling it on late-night infomercials! The truth is that there are no quick fixes that will magically enhance your endurance. But I really think that understanding the nature of endurance—that the limits we feel are generally imposed by the brain, and don’t actually represent an impending physiological crisis—can make a difference. We learn to dig deeper by pushing up against our limits on a regular basis and having the confidence to know that we’re capable of a little bit more.

Alex Hutchinson’s book Endure is available through Amazon and other booksellers. Follow his writing on endurance and human performance on his website and on Twitter.