Cardio Training in the “zero Zone” Is Not What It Seems at First Glance.
Cardio zones don’t exist —at least not in the way they’re presented in your fitness app. Yes, heart rate zones are a way to describe the intensity of your cardio workout, like running or cycling. But the cardio zones everyone keeps talking about are just a way to divide exercise intensity into easily understandable categories. They’re a useful way to describe them, but there are no physiological boundaries at which your body suddenly switches from “zone 2” to “zone 3.” It’s a spectrum, and the specific thresholds vary depending on who you ask (or which app you use), what formula they’re based on, and whether they measured your lactate threshold in a lab or just guessed based on your age.
So, when the term “Zone Zero” came up in health and fitness circles, I instinctively rolled my eyes. This use of the “zone” concept seems like an unnecessary, pseudoscientific approach to what essentially boils down to simply… increasing physical activity. To be fair, the idea of ”moving more” is certainly a positive one, so let me explain what “Zone Zero” cardio actually means and how you can incorporate it into your program.
What is zero-zone cardio?
“Zero” sounds like nothing, or, if not “nothing,” then at best, rest. But rest is already informally referred to as “Zone 1” in many popular concepts (never mind that it may not be a true zone, since sitting still is not a cardio zone). So, we now have a zone zero, located below zone 1 (rest), meaning we’ve invented a category below inactivity .
This semantic confusion is worth noting because it illustrates how the wellness industry typically works: You take something intuitive, give it a technical name, and suddenly people feel like they need an app, a heart rate monitor, and a six-week program to understand what they were already doing or should have been doing all along.
Stripped of all the hype, “Zone Zero” refers to movements that fall somewhere between “exercise” and “total inactivity.” This could be a 10-minute walk after lunch, taking the stairs instead of the elevator, or pacing while talking on the phone. These movements may not be considered rigorous exercise, but taken together, over the course of a day—over a lifetime—they can make a real difference.
The research supporting this practice is compelling, even if the term “zone” is a bit of a stretch. Prolonged sitting is independently associated with health risks, even in people who exercise regularly. Think of it this way: the body doesn’t accumulate physical activity like a savings account; it reacts to the cumulative impact of your movement (or inactivity) throughout the day.
Who is zero zone cardio suitable for?
With this understanding of what zones are and are n’t , Zone Zero can be a great foundation. For example, if you’re an all-or-nothing exerciser, Zone Zero is a way to remind yourself that gentle movements still matter. Or if you’re recovering from an injury, illness, burnout, or for some other reason structured cardio isn’t currently available, Zone Zero is a great way to remind yourself that you haven’t failed by not going to the gym. Gentle movements—even those that barely register on a heart rate monitor—are still movement, and they still have value.
But if you’re committed to a strict and consistent approach to cardio, the concept of a “zero zone” is probably unnecessary. There’s no need to add another source of noise to the fitness world.
The best fitness trackers to track your activity zones.
If you want to track the intensity of your cardio workouts—whether it’s working in the coveted Zone 2, doing more intense workouts, or simply making sure you’re moving enough throughout the day—here are the best trackers for it:
Garmin Forerunner 570
Garmin’s heart rate zone tracking is among the most accurate wrist-based heart rate monitors on the market, and as my colleague Beth Skwarecki writes in her review , the Garmin Forerunner 570 delivers astonishingly accurate heart rate readings. Unfortunately, the price ( currently on sale for $496.97 ) may be a dealbreaker for casual users.
Apple Watch Series 10
This is the best Apple Watch for most people , and it does an excellent job of tracking heart rate zones. It’s also the most convenient option if you’re already an Apple user.
Fitbit Charge 6
When it comes to heart rate monitoring, Fitbit is a decent budget option. However, if you’re looking for something more than a minimalist design, you might want to consider a full-fledged fitness watch, such as the Garmin or Apple models mentioned above.
For more details, I recommend reading this article from Beth to see how the Apple Watch, Fitbit, Garmin, Oura, and Whoop compare in terms of heart rate variability (HRV) measurements.
Result
To put it bluntly: you don’t need to track the so-called “zero zone” of cardio workouts. You don’t need a new metric for this, a special workout, or a wearable device that vibrates to remind you to stand up (though your existing device may already do this, and it can certainly be helpful). The whole point is that the intensity of the exercise should be below the threshold.
What’s truly noteworthy is the behavioral change this concept encourages. Look at your day and honestly ask yourself whether movement is an integral part of your routine or is it limited to a scheduled block. If the latter, consider incorporating walking and stretching breaks into your day. The “zero zone” may not have needed a name, but now it has one, and if knowing it helps you move more, that’s a win.