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Heart Rate Zones: Do They Work or Not?

Kinsey Mahaffey
Kinsey Mahaffey
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From wearable fitness trackers to group fitness classes that use heart rate monitors, it’s not uncommon to be incentivized to train in specific heart rate zones to see the results that you want. Does heart rate training work?

In this article, we’ll take a closer look at the benefits and limitations of training in heart rate zones when it comes to health and weight loss.

You can learn more about additional cardiovascular training formats within chapter 15 of the NASM personal trainer course.

What Are Heart Rate Zones?

A heart rate zone is a specific heart rate range, measured in beats per minute, that is used for monitoring training intensity during exercise or everyday activities. Typically, heart rate zones are calculated based on a percentage of your estimated maximum heart rate.

A wide variety of wearable technology exists that enables fitness enthusiasts and athletes alike to track their workouts and their daily activity. Fitness tracking devices will generally have pre-set heart rate zones used to describe how hard you are working during your workout or activity.

These zones range from very light to maximum (or peak) effort based on the percentage of your maximum heart rate that you’re training in. The American College of Sports Medicine (2018) lists the following target heart rate zones, calculated based on a percentage of the individual’s maximum heart rate:

Very Light <57%
                                          Light       57%-63%
                                      Moderate                                    64%-76%
                                       Vigorous                                    77%-95%
                        Near Maximal to Maximal                                       >96%

 

Do Heart Rate Zones Work?

Heart rate zones can be a great tool when it comes to creating an intentional cardio training program. They can help individuals progress gradually toward their goals (not doing too much too soon), and improve their fitness when used properly. The main challenge with using heart rate zones is determining accurate heart rate values for each training zone for an individual.

“What about the heart rate zones on my fitness tracker?”, you ask. Great question! The limitation of automatically generated heart rate zones, like the ones calculated by fitness trackers and cardio machines, is that these zones are calculated using a formula that only adjusts for your age.

The problem? This calculation doesn’t consider important variables that can influence an individual’s heart rate, like their genetics or medications. Additionally, heart rate zone percentages vary from device to device, so what’s measured as a moderate heart rate zone on one brand of fitness tracker might be a few percentage points different than another brand, while still different from ACSM’s recommended heart rate zones (Scheid and O’Donnell 2019).

In addition, stimulants (hello, coffee!), dehydration, and insufficient recovery can all cause an increase in heart rate during a workout. If your heart rate is elevated due to one of these factors, you might falsely believe that you’re training within your target zone even though your body isn’t working as hard as it would normally have to get into that zone on a normal day. This is problematic for someone trying to reach a health and fitness goal!

What is Max Heart Rate?

Maximal (max) heart rate is important to know if you want to calculate heart rate training zones for a cardio program since the zones are calculated based upon this number. Max heart rate is the highest number of beats per minute that the heart can pump under maximal stress. For safety reasons, this number is generally not measured through fitness testing, but rather through a simple calculation.

How Do You Calculate Max Heart Rate?

The most widely known formula for calculating one’s max heart rate is Haskell’s equation:

220 – age = HRmax

However, this formula wasn’t intended to be used for the calculation of fitness programs because maximal heart rate can vary greatly from individual to individual within the same age group. Instead, a more accurate result will be yielded using the Tanaka formula:

208 – (0.7 x age) = HRmax

Example for a 40-year-old:

208 – (0.7 x 40) = HRmax
208 – (28) = HRmax
180 = HRmax

This equation is not perfect, but it can still serve as a guide to get you started. If you use wearable technology, you can typically adjust your maximum heart rate using the result that you get using the Tanaka formula for slightly more accurate heart rate zones.

What is Target Heart Rate?

Target heart rate is the predetermined exercising heart rate or the intensity that you’d like to train in for the day. For example, if you’d like to exercise at a moderate target heart rate, you will need to calculate 64-76% of your max heart rate, based on ACSM’s target heart rate recommendations.

How Do You Calculate Target Heart Rate?

Heart rate reserve, also known as the Karvonen method, is a way to calculate your target heart rate zone using your resting heart rate. The benefit of using this method is that it further personalizes your training zones given that the resting heart rate varies from person to person. To calculate your resting heart rate, count the number of times that your heart beats in 1 minute right after you wake up.

Do these three days in a row and average the results to get the most accurate count. Then, simply plug that number into this formula to calculate your heart rate training zones:

[(HRmax – HRrest) x desired intensity] + HRrest = Target heart rate

Example: HRmax = 184; HRrest = 65; desired intensity = 70%

[(184 – 65) x 70%] + 65 = Target heart rate
[119 x 70%] + 65 = Target heart rate
83.3 + 65 = 148 (rounded down to the nearest bpm)

An Alternative to Heart Rate Training

An even more accurate way to select training zones (rather than by heart rate alone) is by monitoring your actual effort during exercise. Research has shown that a client’s ability or inability to speak during exercise is indicative of the energy system that the body is using. Look at this chart to see the breakdown (Sutton 2021):

Training Zone Metabolic Marker Rate of Perceived Exertion Description
Zone 1 Below VT1 3-4

- Light to moderate

- Can carry on conversation effortlessly

Zone 2 VT1 to Midpoint 5-6

- Challenge to hard

- Continual talking is becoming challenging

Zone 3 Midpoint to VT2 7-8

- Vigorous to very hard

- Vigorous breathing and ability to talk is limited to short phrases

Zone 4 Above VT2 9-10

- Very hard to maximum effort

- Speaking words is impossible or limited to grunts of single words

*Midpoint: The intensity level halfway between VT1 and VT2.

Instead of relying on the percentage of max heart rate for training zones, VT1 describes the point at which the body is burning equal amounts of fat and carbohydrate as fuel and the aerobic system is working. VT2 describes the point where glucose is the main fuel source, and the training is anaerobic. Knowing the metabolic demand of the intensity of exercise can help you determine which zone is appropriate for your goals.

Additionally, using Rate of Perceived Exertion (how hard the client feels that they are working with 1 being very easy, 4-5 being moderate or somewhat hard, and 10 being maximum effort) along with the talk test make this a simple, and personalized way to measure exercise effort to get results.

What Heart Rate is the Best for Weight Loss?

If you’re tracking your heart rate, the 60-76% heart rate zone (light to moderate) will be a good place to start for weight loss. Using the chart for VT1 and VT2, training in Zones 1 and 2 will be best for clients with weight loss goals.

The key to weight loss is to achieve a calorie deficit (expending more calories than you take in). When it comes to choosing the best heart rate for weight loss, there’s no simple answer for everyone. You will burn more calories per minute while training at a higher heart rate, but you won’t be able to sustain it for long.

You burn more fat as your fuel source at lower heart rate ranges, but if you train in a heart rate range that’s too low, you might not burn enough calories overall to help you get into a calorie deficit for your day. The key is to choose an intensity that allows you to do enough work to see results without it being so difficult that you lose motivation to do it.

When clients ask me what the best type of cardio or exercise is for weight loss, my response is always “The kind that you will do consistently”, and the same applies here.

References:

American College of Sports Medicine. ACSM’s Guidelines for Exercise Testing and Prescription. 10th ed. Philadelphia (PA): Lippincott Williams & Wilkins; 2018.

Scheid, Jennifer L. Ph.D.; O’Donnell, Emma Ph.D. Revisiting heart rate target zones through the lens of wearable technology. ACSM's Health & Fitness Journal: 5/6 2019 - Volume 23 - Issue 3 - p 21-26 doi: 10.1249/FIT.0000000000000477

Sutton, B. G. NASM Essentials of Personal Fitness Training. 7th ed. Burlington (MA): Jones & Bartlett Learning; 2021.

The Author

Kinsey Mahaffey

Kinsey Mahaffey

Kinsey Mahaffey, MPH, is a Houston-based fitness educator, personal trainer and health coach who developed her commitment to lifelong fitness while playing Division I volleyball. She’s passionate about helping others cultivate a healthy lifestyle and enjoys educating other fitness professionals who share this vision. She’s a Master Instructor and Master Trainer for NASM.