When you go out with friends, you're unlikely to be all, Guys, I hit 84 percent of my max heart rate for 12 minutes today. And if you do do that, well, you're probably either a trainer or a fitfluencer on Instagram. But is it really that important for us regular people to know our heart rate—other than the fact that our heart pumping is crucial to, you know, living?

Figuring out your resting heart rate isn't challenging—take your radial pulse by placing two fingers on your inner wrist and counting your heartbeats for 60 seconds. Ideally, to get the most accurate number, you should do this a few days in a row right when you wake up. Or, you can use a fitness tracker to do the work for you. "I use a Fitbit Ionic smartwatch to monitor my resting heart rate during training very closely to see if there are sudden spikes or if my heart rate fails to increase in response to exertion," says endurance athlete Dean Karnazes. "A dramatically increased heart rate or a failure of my heart rate to increase on a normal progression can be warning signs and a reason to alter my training accordingly."

So what the heck do different heart rate zones have to do with our workouts?

"It really depends on your goals," says certified personal trainer Lisa Corsello. "If endurance is a goal, then you're going to want to keep your heart rate up for longer periods of time consistently." Maintaining 60 to 70 percent of your maximum heart rate for 30 minutes is a great place to start—once that becomes your normal, you can build your intensity from there.

First things first: It's important to know your max heart rate (or the maximum times your heart should beat during activity) because that will determine your heart rate for each zone. For a really long time, the formula for calculating your max heart rate was 220 minus your age, but it turns out that might no longer be the best way.

"New research came out on determining your max heart rate levels," says Alec Dragelin, head coach at Orangetheory Fitness Central West End in St. Louis. "You take 207 and subtract 0.7 times your age, and that gets you what we call the theoretical maximum heart rate."

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For example: A 28-year-old would multiply her age, 28, by 0.7, which brings her to 19.6 (but we'll round up to 20). Then subtract 20 from 207, which would give her a theoretical max heart rate of 187. Yay, math!

And yes, it's called a theoretical max heart rate because, well, it's theoretical. "In order to truly determine your maximum heart rate, you would need to do a VO2 Max test, which is considered the gold standard for aerobic capacity." And sure, you can probably find a local lab that has a VO2 tester if you want to get real intense about it, but for most of us, the formula should be enough.

Once you know your theoretical max heart rate, you can go about figuring out which zone you fall into when you exercise. And if that's just way too much math, we've also come up with a handy-dandy guide as to how each one feels.

By all means, move at a glacial pace.

Percentage of your max heart rate: 50-60 percent

What it's good for: Overall health and recovery. "This is really like your recovery zone," says Sara Dimmick, CSCS of Physical Equilibrium LLC. "So this is your long, slow duration—something that you should be able to sustain for a long time."

What it feels like: Walking from your couch to the fridge to get snacks while rewatching Parks and Rec for the third time. Basically, very, very light exercise.

What, like it's hard?

Percentage of your max heart rate: 60-70 percent

What it's good for: Basic endurance and fat burning. "You're still working, but you're not going all out," Dimmick says. If you're one of those brave souls who runs marathons, this would be about your pace, French adds.

What it feels like: You just saw someone walking a really cute dog, and you're trying to catch up to them to pet it. It's like a warm-up or a cool-down—you should be able to carry on a normal conversation in this zone.

Picking up the pace...

Percentage of your max heart rate: 70-80 percent

What it's good for: Working up a sweat, building endurance during moderately long exercise. This is working at an intensity you can sustain for around 30 minutes if you had to, Joel says. You're still working at your aerobic capacity (your body is using oxygen as cell energy).

What it feels like: Not texting your ex back—challenging but doable.

It's getting hot in herrrrrrrrre.

Percentage of your max heart rate: 80-90 percent

What it's good for: "When you get to about 84 percent of your max heart rate, your body goes into anaerobic metabolism," Dragelin says. What this essentially means is your body is short on oxygen, so it has to look for other fuel sources to burn. "You should push for about 10 minutes max at a time in this zone," says Joel French, Ph.D., senior director of research, fitness, and wellness at Orangetheory Fitness. It's in this zone that you start to get those sweet "afterburn" benefits.

"It's called excess post-exercise oxygen consumption," French says. For those of us who love a good acronym, it's often referred to as EPOC. French likens these last two zones to writing a check you can't cash—which, in this case, is a good thing. "You stress yourself a little bit more, and after the workout when you go home, your body is continuing to recover at a high rate to make up for that," he says. "You'll have an elevated metabolism that's continuing to burn up fat."

What it feels like: When you're going all out on the dance floor at a wedding and the sweat is dripping, but you know you can push through it because you're killing it.

A combination of skull and wailing face emojis.

Percentage of your max heart rate: 90-100 percent

What it's good for: This is when you're giving it your all. "You can stay in this zone [for] a max of two minutes, but most people usually reach their limit between 30 seconds and a minute," French says.

What it feels like: When your Flywheel instructor tells you to push for the last 30 seconds, and even though you feel like you're actually dying, you do it because you're terrified of disappointing her. This is an all-out sprint; you're going as hard as you can.

If you want to get specific with how to use your heart rate to your advantage in your training, it's helpful to speak to a trainer about your goals. Heart rate change doesn't happen in a day, so if you're just getting started, think safety first as you push your endurance limits. In the meantime, happy sweating!

Allie Flinn is an L.A.-based beauty, fitness, and wellness writer. She's passionate about working out, neutral colors, young adult novels, and her rescue dogs. Follow her fitness journey on Instagram @allieflinn.

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