For someone who spends their days thinking about science and data, I’m oddly low-tech when it comes to exercise. I have one of the most basic sports watches on the market and I usually leave the built-in heart-rate monitor turned off. Whenever I train for anything—in the past few years I’ve been into trail marathons—I plan my workouts based on feeling. I just find it more enjoyable that way.

But for runners who prefer a more structured approach, one of the first steps is often to figure out their maximum heart rate. Many training plans are built around heart-rate “zones”, which are defined as either percentages of maximum heart rate or as fractions of the range between resting and maximum. If you’re getting into running—or simply curious about the commonest method of calculating your maximum heart rate—read this edition of Well Informed. Our column on health and well-being also has a newsletter you can sign up for. It lands in your inbox every Sunday.