Exercise is a healthy and, one might argue, necessary part of our lives. The guidelines from public health organizations tell you to aim for at least 150 minutes of “moderate” exercise each week, and that each minute of “vigorous” exercise counts double. That raises the question: What the hell is “moderate” exercise? How do you know when you’re doing it? Moderate exercise is sometimes conflated with "zone 2" exercise. These two things aren't exactly the same, but they do overlap a bit. I'll get into the difference below. Moderate exercise includes activities like walking and casual bicycling, and it counts whether you think of it as a workout or not. Getting enough moderate exercise has benefits for your heart, metabolism, mental health, and more—so let's dig in to what it is and how you can know when you're doing it.
Scientists measure METs, but you don't have to If you use a fitness tracker like the Fitbit Air, it may try to tell you that "moderate" exercise occurs when you reach a certain heart rate. This isn't actually the case. The scientists who came up with the exercise guidelines didn't use heart rate as their guide. Instead, they used charts that measured how many "METs," or metabolic equivalents, each type of exercise requires.
