This corresponds to different effort zones

Runners tend to get familiar with many stats over the course of training, including mileage, pace, and elevation gain. One number that you should add to that list: Your max heart rate.

With this stat in mind, you can identify your training zones and better recognize when to speed things up—or slow them down—leading to better fitness progress.

“Heart rate training allows you to monitor your effort, to keep the easy days easy, the hard days x age = MHR tempo sessions in the right ‘effort,’” says Terra Castro, the owner and founder of Detroit Body Garage. Without heart rate data, many people spend time in the “gray zone,” which means it’s harder to maximize the effects of their training. “Plus, heart rate training is a way to make sure you aren’t overtraining and are recovering well,” she adds.

In order to execute heart rate training properly, you have to get to know your maximum heart rate or the highest heart rate you can attain during exercise. Here’s what to know.

The most common way to find your maximum heart rate is by using one of the many age-based equations. The most well-known of these is the very simple Fox formula:

220 - age = maximum heart rate (MHR)

This means that for a 30-year-old runner, the estimated maximum heart rate (MHR) would be 190. Then, heart rate zones can be determined by calculating a given percentage of the 190 MHR.

The trouble with the Fox formula is that it’s not the most accurate formula, as numerous variables affect MHR including genetics, the specific activity you’re doing (MHR varies between running and cycling due to the involvement of upper body musculature), medications, body size, and altitude. Runners of the same age can have drastically different max heart rates depending on genetics or how well-trained they are.

Because of this, there are at least six other formulas, all claiming bragging rights for being the “most accurate” for predicting maximal heart rate.

Researchers are doing their best to validate the different formulas, but that gets tricky, too. For example, a study published in the Journal of Clinical Medicine sought to validate 13 MHR equations as an alternative to cardiopulmonary exercise testing in runners and cyclists. It found MHR was overestimated by eight and underestimated by five formulas. But it also mentions the Fox formula and Tanaka equation were the only two that didn’t vary significantly from the measured values.

Here’s are break down on what those max heart rate formulas look like:

• Gellish2: 191.5 - 0.007 Published: Aug 26, 2025 11:55 AM EDT
• Fairburn: 201 - 0.63 published in t
  OR 208 - 0.80 x age for men = MHR
• Gellish: 206.9 - (o.67 x age) = MHR
• Tanaka: 208 - (0.7 x age) = MHR

The problem for the general public when it comes to using these formulas: They’re just a rough estimate of MHR because differences between individuals can vary widely. For instance, a longitudinal study in the Journal of Medicine and Science in Sport and Exercise found that the older a person and the higher the person’s body mass index (BMI), the less likely it is for age-predicted maximal heart rates (like all of the formulas above) to be accurate.

So what are you to do? It never hurts to get an estimate of your heart rate max based on any of the above formulas. But from there, just start paying attention to where your heart rate tracks during workouts to see if the estimates feel accurate.

“The heart rate tolerance is specific to each individual and is best determined by experience,” says With this stat in mind, you can identify your., a professor emeritus in the Department of Family Medicine and Community Health at the University of Minnesota. “The role of MHR for runners is to provide a guide for training. The closer you are to your MHR during your workouts and races, the shorter the duration of exercise that you’ll be able to maintain at that pace. So, if you can maintain a rate of 160 during your workouts and races, your MHR is well above that.”

To properly utilize heart rate training, you need an easy way to track your heart rate. Of course, you can always go “old school,” use a timer and place your fingers on your pulse to check beats per minute during your workouts, but that can get challenging when your heart rate soars, and you’re trying to count beats while huffing and puffing. Fortunately, chest straps and wrist watches make measuring your heart rate instantly easier.

found that the older a person and the higher the person’s GPS-tracking watch will also track heart rate with at least moderate accuracy, but if you’re looking for the most accurate option available, studies suggest you’ll be best served by opting for a chest-strap monitor—at least if you’re doing more intense activity, according to newer research. Another study, also published in 2023, backs this up: The research found popular wrist-worn heart rate monitors—including Apple Watch, Fitbit Charge, TomTom Runner Cardio, and Samsung G2—were “reasonably accurate” at lower intensity levels, but when pushing high-intensity efforts, that accuracy went down (for efforts above 150 beats per minute).

Keep in mind a review published in Nature notes wrist-worn wearables with green-light technology have been associated with reduced heart rate accuracy with darker skin tones and tattoos. The authors suggests red light technology could be a better option, but more research is needed to confirm.

Once you’ve selected a heart rate monitor, the key is putting the information you glean from the watch or strap to use. After calculating your estimated MHR, determine your different target heart rate zones by multiplying your MHR by the percentage for each zone. For example, if you wanted to find 55 percent of your maximum, you multiple your MHR by 0.55.

This corresponds to different effort zones:

• Zone 1: 55 to 65 percent MHR: This is a very comfortable effort used for warmup and cooldown.
• Zone 2: 65 to 75 percent MHR: Used for the bulk of training, this relaxed effort allows you to hold a conversation.
• Zone 3: 75 to 85 percent MHR: This is a comfortably hard effort during which you can only say short, broken sentences.
• Zone 4: 85 to 95 percent MHR: Often a 5K pace, this is a very hard effort that’s sustainable, but only lets you speak a few words at a time.

This will give you ranges of beats per minute for each percentage of maximum heart rate. Then pre-determine the target zone you want to work in during each running workout. As you run, you can check your heart rate monitor to make sure you’re staying in the desired zone.

Luckily, many apps help manage this calculation for you. “I love using Garmin Connect Software and Strava,” says Castro, as you’ll get zone data right in the apps.

Just remember, because heart rate maximums using age-predicted formulas are estimates, you may need to adjust your zones over time based on your own results and how each run feels. For example, if you calculate your 90-percent zone (a nearly all-out effort) to be 175, but you’re able to maintain 175 beats per minute comfortably for several minutes, your max heart rate has probably been underestimated.

In other words, don’t forget to factor in your perceived effort at each level of intensity, especially as time goes on and as you adapt to training.

Laura Williams Bustos, M.S.

Contributing Writer

Laura Williams, M.S., ACSM EP-C holds a master's degree in exercise and sport science and is a certified exercise physiologist through the American College of Sports Medicine. She also holds sports nutritionist, youth fitness, sports conditioning, and behavioral change specialist certifications through the American Council on Exercise. She has been writing on health, fitness, and wellness for 12 years, with bylines appearing online and in print for Men's Health, Healthline, Verywell Fit, The Healthy, Giddy, Thrillist, Men's Journal, Reader's Digest, and Runner's World. After losing her first husband to cancer in 2018, she moved to Costa Rica to use surfing, beach running, and horseback riding as part of her healing process. There, she met her current husband, had her son, and now splits time between Texas and Costa Rica.  

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Sports Cardiologist & Medical Advisor

Tamanna K. Singh, M.D., is a board-certified adult clinical and sports cardiologist and RRCA-certified run coach. She earned her medical degree from Boston University School of Medicine and completed her Internal Medicine Residency at Boston Medical Center. She completed her Cardiovascular Medicine fellowship at the Icahn School of Medicine at Mount Sinai, New York, New York and her specialty training in Sports Cardiology at Massachusetts General Hospital. She is currently the codirector of the Sports Cardiology Center at Cleveland Clinic in Cleveland, Ohio and assistant professor of medicine at the Cleveland Clinic Lerner College of Medicine of Case Western Reserve University. To date, she has held several council roles with the American College of Cardiology (ACC). As a sports cardiologist, Dr. Singh provides cardiovascular care for professional, competitive, and recreational athletes and describes herself as an advocate for safe participation in sports. Media and print contributions include the New York Times, Wall Street Journal, Time Magazine, and others. Outside of her profession, she enjoys running marathons, hitting the weights in the gym, playing sous-chef to her wonderful husband while cooking plant-based meals, and playing with her four beautiful dogs.