Tracking your heart rate is useful for gauging how hard you’re working during exercise, and thanks to all the smartwatches and wearables available these days, it’s easy to keep tabs on your real-time heart rate and adjust your intensity in the moment. But to use your heart rate to understand your workout, you’ll also need to understand heart rate zones.
If you’re following along with something that says something like “you should be in zone 2 here, and zone 3 there,” the first question you need to ask is how many zones are in this system?
Four-zone and five-zone systems are most popular; there are lesser-known ones that go down to three or up to six. The zones also don’t always agree from one system to another—Orangetheory and Peloton both use a five-zone system, but divide their zones in slightly different places. So you truly have to ask whoever designed the workout what they’d like you to do.
With those caveats in mind, let’s look at a few common setups.
If it’s a five-zone system
Five-zone systems are the most common. If there are five zones in a system, they usually go something like this:
- Zone 1: 50% to 60% of your maximum heart rate (MHR), though some systems will go up to 65%
- Zone 2: 61% to 70% of MHR; some systems will go up to 75%
- Zone 3: 71% to 80%, or it might be more like 76% to 85%
- Zone 4: 80% to 90%, or sometimes 85% to 95%
- Zone 5: all the way up to 100%
In these systems, zone 1 is for warmups or very easy recovery between intervals. Zone 2 is for easy aerobic training, like a light jog. Zone 3 is for stuff that feels like a medium intensity—maybe a faster jog. Zone 4 is when things get intense, and you’ll only bump in zone 5 for a few seconds at a time during your hardest intervals. You can’t sustain work in zone 5 for much longer than that.
If it’s a four-zone system
Four-zone systems cover the same general territory, but break it down into fewer, bigger chunks. Usually they do this by combining the first two zones, to give you something like this:
- Zone 1: anything below 70% (or 75%)
- Zone 2: 71% to 80% (or sometimes 76% to 85%)
- Zone 3: 81% to 90% (or 86% to 95%)
- Zone 4: Everything on up to 100%
In these systems, easy-effort endurance work is generally done in zone 1 (instead of warming up in zone 1 and considering the workout itself to be zone 2). Zone 2 is for medium efforts, zone 3 for hard efforts, and zone 4 for absolutely killer, short intervals.
How to find your maximum heart rate
Now that you know the zones, you’re only missing one thing: your maximum heart rate, which forms the basis for them all.
Commonly, these systems will recommend you subtract your age from the number 220 to find your max heart rate. Occasionally they’ll use another formula. But these formulas are often wrong, since they can only give an answer that is correct for most people on average. Averages don’t really help when you’re trying to find your own individual zones, since a difference of 10 or 20 beats could leave you exercising a whole zone higher or lower than you think you are.
Ideally you’ll do a max heart rate test as we described here, or look up the highest heart rate that your device recorded during one of your hardest workouts.
Another way is to use perceived effort (in other words, how you feel) to gauge whether you’re working in the right zones. In a five-zone system:
- Zone 1 will feel very easy, barely like you’re exercising at all.
- In zone 2, you’ll start to feel hot and sweaty, but you can still carry on a conversation.
- In zone 3, your breathing will get a bit heavier, and you’ll only be able to say a few words at a time.
- In zone 4, you’re working hard and not in the mood to talk, but you probably feel like you could keep this effort up for a while—or a few more minutes at least.
- Zone 5 is your absolute top speed, and you can only stand it for a few grueling seconds.
If you aren’t sure of your max heart rate, try using this effort-level guide for a while. When you actually do get to a workout that calls for zone 5, give it your all—then check your heart rate monitor to see what number it gave you.