Chances are you're wearing a watch or fitness tracker that tells you your heart rate, but do you know what that every-evolving number means exactly?

By Julia Malacoff
Photo: mediaphotos / Getty Images

Heart-rate training is becoming more and more common. Workouts based on heart rate, like Orangetheory Fitness, are popping up nationwide. There is an increased popularity of LISS (low-intensity steady state) cardio thanks to mega-celeb trainers like Kayla Itsines. Plus, accessibly priced fitness trackers with heart-rate monitors built in are probably on the arms of more friends than ever. But simply knowing your heart rate is only half the equation. To get the best results from these types of workouts, you really need to learn your specific heart-rate zones for low, moderate, and high-intensity exercise, and checking out the chart on the cardio machines at your gym *probably* isn't going to cut it-especially if you're new to the gym or have been working out hard for years already. Learn why, then test your skills and your rates with this 30-day cardio HIIT challenge that's guaranteed to boost your heart rate.

How to Find Your Zones

To figure out your personal heart-rate zones, the first thing you'll want to do is determine your max heart rate, or the hardest you can work during exercise. Then, you'll calculate your zones. For a low-intensity workout (which is great for burning fat), you'll want to keep your heart rate between 35 and 50 percent of your max heart rate. Moderate intensity is 50 to 70 percent of your max heart rate and will help increase your endurance. High-intensity exercise is training at 70 to 90 percent of your max heart rate and will help increase your speed and power.

To get started, there are a couple of ways to find your max heart rate.

Step Test

You can do this on any cardio machine while wearing a heart-rate monitor. "For example, if you're on a treadmill, go at baseline intensity or 'really easy,' says Michael Bann, a head coach at OPEX Fitness in Scottsdale, AZ. "Run for one minute at that pace. Increase the speed by 0.5, and run for another minute. Continue doing the same pattern of incremental increases. Whenever you can't sustain that for a minute, that is your max heart rate." Ideally, you want to do this under the supervision of a coach, doctor, or someone else with appropriate credentials to ensure you don't push it too hard, and you definitely want to make sure you're cleared for exercise by your doctor before attempting anything like this. Once you've got your max heart rate, simply calculate the percentages of that number for low-, medium-, and high-intensity zones, and you'll be set.

The Formulas

The most common formulas are 220 − your age or 207 − (your age × .7), says Cary Raffle, a certified personal trainer and exercise science pro in NYC. The latter formula is newer and thought to be more accurate. Another option is the Karvonen formula, which takes into account your resting heart rate to target specific training zones. "To measure your resting heart rate, measure your pulse at your wrist first thing in the morning without an alarm clock or screaming kids," he says. "Count the number of beats in 30 seconds and multiply by two. Consider retaking it on two or three mornings and averaging." Then, plug it into this formula using the percentage of intensity you plan to exercise at:

[(220 − Age − Resting HR) × %Intensity] + Resting HR = Target Heart Rate

It can be helpful to create a range for yourself since your heart rate is unlikely to stay *exactly* the same during an entire workout. So for example, if you have a resting heart rate of 60, you're 30 years old, and you want to exercise at the upper end of moderate intensity, which would be 60 to 70 percent intensity, your formula would look like this:

[(220 − 30 − 60) × .6)] + 60 = 138 bpm (beats per minute)

[(220 − 30 − 60) × .7] + 60 = 151 bpm

Now you have a range to stick within (138 to 151 bpm) during your workout.

It's also important to take stock of where you stand heart-rate-wise every few months. "As your fitness level improves, retake your resting heart rate and recalculate your training zone," says Raffle. That way, you can adjust your zones to line up with your hard-earned progress.

Why You Should Heart-Rate Train

The benefits of heart-rate training, when done right, are pretty incredible. "For the general population, heart-rate training can help lose or maintain body weight, improve overall fitness, reduce triglyceride, cholesterol, and blood sugar levels, improve insulin sensitivity, and help lower blood pressure," says Raffle. That's because when you're hitting the optimal zones for fat loss and improved endurance regularly, you'll see results-pretty straightforward. "For athletes, it can help improve cardiac output, increase VO2 max (the amount of oxygen you can utilize during intense exercise), and lead to improved athletic performance," adds Raffle. Plus, there's the fact that many people find comfort in knowing exactly how hard they're working. "Some people (including me) find it easier to stay in the zone and train harder when they are looking at a number," he says.

What's more, having information about your optimal heart-rate zones and sticking to them is simply safer, especially for those newer to exercise. "Guessing your intensity level during a cardio workout could be dangerous in terms of overestimating or underestimating one's numbers," says Ava Fitzgerald, C.S.C.S., C.P.T., U.S.A.W., a sports performance coach at the Professional Athletic Performance Center. "This could cause someone to push past a desired intensity, or to an intensity that might be too extreme." Of course, there's also the chance that you could miss out on a great workout and see fewer results over time because you're not pushing yourself as hard as you think. (Related: This Strength HIIT Workout Has Triple the Body Benefits)

High-Intensity Isn't Always Better

Despite a lot of good information out there about heart-rate training, there are also some misconceptions about the idea. "The growing popularity of heart-rate monitoring among fitness enthusiasts has caused a bit too much focus on the heart rate, with many people assuming that they should get their heart rate as high as possible," says Raffle. This isn't the case, and hitting your highest heart rate ever isn't the goal. Instead of progressively hitting higher heart rates, you actually want to see your heart rate during similar activities go down on the whole over the course of several months of heart-rate training. (Related: 5 Cool Ways to Use Your Fitness Tracker That You Probably Haven't Thought Of)

"Your heart pumps oxygen-rich blood throughout your body to fuel aerobic activity," explains Raffle. "The stronger the heart muscle, the more blood it pumps every time it beats, therefore the fewer times it beats per minute." This, in turn, lowers your heart rate. So, how do you accomplish this? Moderate-intensity training is key, according to Raffle. "You want to be able to run faster without your heart having to beat faster," he says, which sort of saves that extra energy (heart beats and oxygenated blood) for when you really need it during a sprint or faster tempo. In order to truly understand the difference between low-, moderate-, and high-intensity training, it's helpful to actually take notice of how your body feels when you're in different zones.

Everyone's Max Heart Rate Is Different

In general, physical fitness levels can be responsible for a disparity between two people's max heart rates and therefore their training zones. "Those who have been exercising would be able to do more at a lower heart rate as opposed to those who haven't been physically active and can only do limited work before their heart rate spikes," says Jon De La Torre, an ACSM-certified personal trainer at DIAKADI in San Francisco. Of course, there are exceptions, and there are all kinds of things that can affect your heart rate (some of which have nothing to do with fitness), which is why most trainers advocate for looking beyond the standard heart-rate charts and formulas. "Heart-rate ranges can differ by age, height, weight, body composition, and stress level," adds De La Torre.

Those who are relatively fit could still have higher heart rates simply because of genetics. While the science is still emerging, there are at least 14 known genes that influence resting heart rate (how fast your heart beats when you're completely relaxed), according to a 2013 study in Nature Genetics. It stands to reason that people with genetically high resting heart rates may also have higher training zones and max heart rates than those who don't.

What's more, your own max heart rate can vary depending on what activity you're doing. "For example, your max heart rate on a stationary bike is NOT the same as your max heart rate for running," explains Sam Smith, another head coach at OPEX Fitness. "Different movements produce different stressors on the body, both positively and negatively." So if your main sport is running, you'll want to be aware of the fact that your max heart rate and training zones could be different if you're doing a CrossFit workout with a kettlebell. Whatever your sport of choice, learning your personal heartrate zones arms you with the knowledge to get the best possible workout-and results-through a minimal time investment.


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