How to calculate maximum heart rate for exercise

Maximum heart rate (HRmax) is an important tool to uncover cardiovascular disease. During stress testing, age-expected maximum heart rate is used as a guideline for when the test should be concluded. If the test is finished before the load is high enough, you risk not to detect subclinical heart disease. Therefore, it is of great clinical relevance to have a way to accurately estimate HRmax.

The traditional formula for determining HRmax is "220 minus age", but can underestimate HRmax by up to 40 beats per minute in seniors. In fact, the method is inaccurate already at an age of 30–40 years, and gets more inaccurate the older you are.

In The HUNT Fitness Study, we measured accurate maximum heart rate in 3,320 healthy adults aged between 19 and 89. Based on these tests we made a completely new formula which estimates maximum heart rate far more accurately than "220 minus age". The HRmax Calculator is based on this formula: "211 - 0.64*age".

Read the full article:
Age-predicted maximal heart rate in healthy subjects: The HUNT Fitness Study

Maximum heart rate and beta blockers

Our HRmax Calculator asks you to check a box if you use beta blockers. The reason for that is that heart patients and others on beta blockers will have a reduced maximum heart rate.

Beta blockers bind to adrenaline receptors and block access for adrenaline molecules. Adrenaline causes the heart to pump both harder and faster. Hence, beta blockers reduce the maximum heart rate. The magnitude of the reduction depends on the dosage, so we recommend that you test yourself to find an exact HRmax.

Find your exact maximum heart rate

Our research shows that the variation in maximum heart rate within age groups is fairly large. Genetics contribute more to maximum heart rate than physical fitness. Therefore, it's hard to make a calculator that can estimate maximum heart rate precisely, and we recommend all of you who want to find your real HRmax to test yourself by pushing yourself to exhaustion:

1. Warm up thoroughly so you start sweating.
2. Do two intervals, each four minutes long. During the intervals you should be too short of breath to talk. Intersperse each interval with three minutes of active rest.
3. Start the third interval, but two minutes in, increase your speed even further an run until you're too exhausted to continue. Your HRmax will be the highest heart rate you reach. The heart will reach a plateau at which it cannot beat any faster, regardless of how much you increase the workload.

If you don't have a heart rate monitor, you can measure the maximum heart rate by holding two fingers to your neck for 30 seconds right after finishing the test. Double the number you get to find your HRmax.

Maximum heart rate and exercise

During 4x4 interval training, you use your maximum heart rate to give the heart good exercise. Our HRmax Calculator calculates at which heart rate you should exercise when performing this kind of interval training. The 4x4 principle can be used in a variety of activites, including running, biking, swimming and rowing.

If you're looking to take your exercise to the next level, figuring out your target heart rate (HR) zone is a great way to burn the most calories and get the most out of your workout time. A big part of that HR calculation involves your maximum heart rate (MHR), which refers to the fastest rate at which your heart will beat in one minute.

Read on to learn how to determine your MHR, what your MHR means and doesn't mean, which factors impact MHR, and how to use it to push yourself just the right amount.

Maximum Heart Rate

Maximum heart rate is the highest number of beats your heat can pump per minute when it's under high stress (physical or otherwise). You can estimate your maximum heart rate using your age and a simple equation. You simply subtract your age from 220. For example, a 40-year-old's estimated maximum heart rate using this formula would be 220 – 40 years or 180 beats per minute (bpm). However, this is not the only way you can estimate your maximum heart rate. Read more about them below.

Why It's Important to Know Your MHR

Maximum heart rates can vary from person to person and they are not an indicator of physical fitness. In other words, it doesn't rise as you get stronger or faster, and it doesn't mean that someone with a higher MHR is in better shape than you.

However, knowing your max HR can help you track your fitness progress and determine your target heart rate. That can give you a more exact method of determining your exercise intensity than using your perceived exertion.

Here are a few examples:

• Low intensity: 40% to 50% MHR
• Moderate intensity/healthy heart zone: 50% to 60% MHR
• High intensity/fat-burning zone: 60% to 70% MHR
• Max intensity: 85% to 100% MHR

Factors That Affect MHR

While most formulas calculate a ballpark MHR based on your age and gender, it's actually more complicated than that. All of these factors can come into play in determining your MHR:

• Age: Your MHR can decline as you age.
• Altitude: Altitude can lower your MHR.
• Fitness: MHR has nothing to do with how physically fit you are.
• Genes: Your MHR is influenced by your genes.
• Individual differences: MHR can vary significantly even among people of the same age and sex.
• Size: MHR is usually higher in smaller people, which is why women often have a higher MHR than men.
• Working out: Training doesn't really change your MHR, but if there is any change, it may get lower as your body experiences expanded blood and heart volumes.

How to Measure MHR

There are many formulas for calculating your maximum heart rate, however, the most studied are the following:

• Fox formula (most common formula for men and women): 220 - age
• Gulati formula (women only): 206 - (0.88 × age)
• The HUNT formula (men and women who are active): 211 - (0.64 x age)
• Tanaka formula (men and women over age 40): 208 - (0.7 × age)

Age-Based MHR Formulas

For many years, the typical formula for calculating your maximum heart rate was 220 minus age. Eventually, experts realized there's a big problem with that particular formula, as it doesn't reflect the way heart rate changes with age.

MHR actually decreases as we age. One reason is that getting older actually depresses the sinoatrial node, the natural pacemaker for the heart. That's something the Fox formula doesn't take into account.

In fact, there's some suggestion that using that formula to calculate heart rate could give you numbers that are way off—maybe by as much as 12 beats per minute up or down. That's a huge gap.

Many of these formulas have also been found to overestimate the maximum heart rate for women, which is why Martha Gulati and her colleagues developed a female-specific formula to better predict a woman's maximum heart rate based on age.

Keep in mind that unless you're in a laboratory setting where you can be hooked up to machines, it's tough to get pinpoint accuracy of your MHR. So we do the next best thing: make an informed guess.

If you don't want to do the math, you can also use a heart rate monitor to track your intensity, but you will need your MHR as a starting point.

Using the MHR Formula

Below is an example of how to use the Tanaka formula to calculate a maximum heart rate for a sporadic exerciser who is 45 years old:

Maximum Heart Rate Formula

208 - (0.7 x 45) = 177 beats per minute 

Determining Exercise Intensity

If you use the calculation above, you come up with a number that equals that maximum amount of beats your heart will beat in one minute. Using that information, you can actually figure out how hard to work during exercise based on your level of fitness.

• If you're very sedentary with no exercise at all, you should work at about 57% to 67% of your MHR.
• If you engage in minimal activity, you should work at 64% to 74% of your MHR.
• If you exercise sporadically, you should work at 74% to 84% of your MHR.
• If you exercise regularly, you should work at 80% to 91% of your MHR.
• If you exercise a lot at high intensities, you should work at 84% to 94% of your MHR.

So our sporadic exerciser in the example above should aim for a target heart rate zone of 131 beats per minute at the lower end and up to 149 beats per minute at the higher end.

That's just a general guideline to follow, though. The best way to get more specific with these numbers is to note how hard you're working at different levels of intensity, or your perceived exertion (how hard you feel your body is working on a scale of one to 10).

Say you're working at 148 beats per minute. You might match that to a level on the perceived exertion scale. As you practice doing that, you'll get a better idea of what you can handle and when you need to speed up or slow down.

Using the Perceived Exertion Scale to Measure Your Workouts

You can also measure your heart rate and determine if you’re exercising within your target heart rate zone by using a heart rate monitor or simply taking your pulse on the inside of your wrist by counting the number of beats per minute.

A Word From Verywell

Knowing your maximum heart rate helps you push yourself to work as hard as you can—but keep in mind that you can only sustain this maximum effort for a short period of time. What's more, exercising above your anaerobic threshold causes you to produce lactic acid, which can create post-exercise muscle soreness.

If you have an injury, illness, or take certain medications, it's smart to consult your doctor. For example, beta blockers, common medications for blood pressure, can interfere with the heart's natural response.

Whether you're exercising for health, fitness, or weight loss, to get the best results it's smart to vary your workouts in each of the heart rate zones.

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