Runners often swear by the 80/20 rule for organizing their training—but this is no relation to the Pareto principle of the same name. Let’s talk about where the 80/20 idea comes from, how to implement ...

One is the idea that most of your running should be easy. That’s often summed up (as in the title of Matt Fitzgerald’s 2014 book on the topic) as 80-20 running: around 80 percent of your ...