How To Calculate Your Heart Rate

The human heart beats about 100,000 times a day. That’s about two billion heartbeats during a lifetime! How many of those should you spend on a workout?

Exercise is one of the best ways to increase your life expectancy, due in part to the effect of cardiovascular (or aerobic) exercise. You can increase this component of your fitness by doing steady aerobic work (walking, running, cycling, and swimming are just a few examples) at a given percentage of your maximum heart rate. But how the heck do you figure out what that is?

The most accurate way to determine your maximum heart rate is by undergoing an incremental exercise test to maximum exercise level. This is not fun, and requires precise monitoring with specific equipment. Your doctor is probably not going to prescribe this just because you ask for it (but they might!). More commonly, personal trainers, exercise physiologists, health coaches, and other exercise professionals use a formula that estimates your maximum heart rate, based on your age:

Calculating Maximum Heart Rate – Normal, Healthy People

When planning day-to-day exercise, there is a commonly used equation to estimate your maximum heart rate that is actually quite simple, and is empirically based (meaning based on solid research). It’s not as precise as the exercise testing, but it is much easier. All it takes is a little math.

Maximum Heart Rate (in beats per minute) = 220 – Age in years

For example, the maximum heart rate calculation for a 35 year old would look like this:

Maximum heart rate = 220 – 35

Maximum heart rate = 185 beats per minute

However, it is important to note that this equation can overestimate or underestimate your maximum heart rate by as much as 12 to 15 beats. In general, this variation is mostly due to age, but can also be influenced by factors such as fitness level and individual genetic makeups, which are impossible to account for in the estimation.

If you are over 40, the above equation may overestimate your maximum heart rate as 12-15 beats per minute higher than it actually should be. This means that the number the equation tells you could be 12-15 beats per minute higher than it should be, and you should use caution with exercise that takes your near your calculated heart rate max.

If you are under 40, the above equation may underestimate your maximum heart rate by 12-15 beats per minute. This means that exercise that takes you near the calculated maximum heart rate may not truly be your max – you may be exercising at a lower intensity than you mean to.

There are two other variations for calculating maximum heart rate for specific populations, which take into account more specific variables.

Calculating Maximum Heart Rate for Obese Individuals

This variation on the maximum heart rate equation takes into account the low fitness level that very often corresponds with obesity. It also takes into account the health challenges an individual may face, including heart disease, which may further increase risk of injury or cardiac event brought on by strenuous exercise.

Maximum Heart Rate, Obese Individuals (In beats per minute) = 200 x (0.5 x Age in years)

For example, the maximum heart rate calculation for a 50 year old obese individual would look like this:

Maximum heart rate = 200 – (0.5 x 50)

Maximum heart rate = 200 – 25

Maximum heart rate = 175 beats per minute

Calculating Maximum Heart Rate for Older Adults

Your heart has its own natural pacemaker, which creates the electrical impulse that causes each heartbeat. As you age, these impulses – and subsequently your heartbeat – gradually slow. (This is a normal process and nothing to worry about!)

This physical difference means that in order to be more accurate, if you are an older adult (above the age of 60), you should be using a slightly different formula to estimate your maximum heart rate. Older adults can make the same changes to cardiovascular fitness as any other age group, and the relative intensity that you can work to as an older adult is unchanged. A workout that brings you to about 70% of your maximum heart rate will feel the same whether you’re 37 or 73. It’s only your actual heart rate that will be different. So it’s worth planning well. Using the following modified formula will ensure that you A) stay within safe limits when exercising and B) continue to make progress and increase your fitness levels!

Maximum Heart Rate, Older Adults (In beats per minute) = 208 x (0.7 x Age in years)

For example, the maximum heart rate calculation for a 73 year old would look like this:

Maximum heart rate = 208 – (0.7 x 73)

Maximum heart rate = 200 – 51

Maximum heart rate = 149 beats per minute

With respect to all of these situations, it’s important to listen to your body when gauging your exercise intensity. If you feel like you’re working moderately, very hard, or somewhere in between, then it’s ok to use that to gauge your workout intensity as well. We call this a rating of perceived exertion, and it has a strong parallel to heart rate when it comes to gauging intensity. You can use both methods to gauge intensity, or you can aim for a target heart rate and work within 5-10 beats per minute of that number.

 

References
Miller, Wayne C., Janet P. Wallace, and Karen E. Eggert. “Predicting Max HR And The HR-&VO2 Relationship For Exercise Prescription In Obesity”. Medicine & Science in Sports & Exercise 25.9 (1993): 1077-1081.
Plowman, Sharon A and Denise L Smith. Exercise Physiology For Health, Fitness, And Performance. 4th ed. Baltimore: Lippincott Williams & Wilkins, 2014.
Tanaka, Hirofumi, Kevin D Monahan, and Douglas R Seals. “Age-Predicted Maximal Heart Rate Revisited”. Journal of the American College of Cardiology 37.1 (2001): 153-156.

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