Our Resting Heart Rates Vary Wildly, FitBit Data Reveal

Depending on the heart rate your doctor measures during your annual checkup, you might get a stamp of approval — or a raised eyebrow and questions about your overall health.

But a new study confirms that a normal resting heart rate isn't the same for everyone. Data from over 92,000 FitBit-wearers were analyzed in a new PLOS ONE paper, showing that average resting heart rates ranged between 40 and 109 beats per minute (BPM). Though not all of those rates are necessarily healthy, the study did find that each individual’s heart rate stayed fairly consistent over time.

Monitoring your heart rate through devices like FitBit and understanding the various factors that can influence it has the potential to improve your long-term health. 

Resting heart rate (RHR) is a crucial health indicator that shows how many times your heart beats per minute when you're not active. It's a vital sign and can tell us about our overall health, the risk of various health issues, how fit we are, and how our body responds to exercise. 

RHR varies among individuals and can be influenced by many factors. However, there can be confusion in its definition and how it's measured, especially with the growing use of wearable devices for heart rate monitoring. It's important to have clear definitions and consistency in measuring RHR, especially as more people use these devices for health monitoring.

Read More: What Does the Heart Do?

A normal resting heart rate likely lies between 60 and 100 BPM, and might dip down to 40 in elite athletes. Generally, lower heart rates are a sign of better cardiovascular health. Recent research has suggested that a heart rate changing over time could also hint at other conditions happening in the body. For example, one study tracked the phases of menstrual cycles based on daily shifts in heart rate. 

The dataset for this study included people ages 18 to 100 with body mass index values between 15 and 50. The average user had a rate of 65 BPM, which fluctuated depending on factors such as sex, age, BMI, and how much sleep they had gotten. Data from individual users were stripped of identifying information.

When Quer and his team studied the FitBit data — information that users consented to share — they confirmed much of what doctors already know about heart rates.

The average resting heart rate for women can vary, but it typically falls within the range of 78 and 82 beats per minute. Women had higher average heart rates than men, and those who got a better night's sleep had lower resting heart rates. Individuals with a higher BMI typically had higher heart rates. 

But altogether, the factors the researchers were able to include only accounted for 10 percent of the difference in heart rate between people. The other 90 percent might be due to fitness or other factors the team didn’t study, Quer says.

The study also found that each person’s heart rate was remarkably stable over time. Interestingly, women of childbearing age had heart rates that fluctuated the most. This might be related to heart rate changes through the menstrual cycle, Quer says.

Read More: How a Heart Can Stop After a Forceful Impact

You can easily find your resting heart rate manually or with a fitness tracker like a FitBit. Checking your resting heart rate is important because it can provide valuable insights into your overall health and fitness level. It serves as an indicator of how efficiently your heart is working, and any significant changes in your resting heart rate may signal underlying health issues.

You can measure your resting heart rate manually by placing your index and middle fingers on your non-dominant wrist, and feel for the pulses or beats. To measure your heart rate in beats per minute, you can count for a full 60 seconds.

To measure your resting heart rate electronically, you can rely on a tracker and it should show around 85 percent of your maximum predicted heart rate. If your heart rate is consistently higher or lower than usual, consult your doctor.

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A variety of factors can influence a heart rate. Physical activity and exercise, as well as, medical conditions, such as asthma, high blood pressure, or high blood sugar associated with diabetes can impact the rate. Certain substances, like caffeine and alcohol, can also lead to changes in heart rate. Finally, external factors such as dehydration and smoking may contribute to fluctuations.

Exercise, like endurance sports and yoga, can lower the resting heart rate, potentially benefiting those with high heart rates. 

Asthma can increase a heart rate due to low oxygen, high carbon dioxide and stress during an asthma attack. 

Blood pressure influences the heart rate differently in different parts of the body, with a reverse relationship in central blood pressure and a positive correlation in peripheral blood pressure. 

High blood sugar is associated with an increased risk of developing diabetes, particularly in individuals with high resting heart rates. 

Caffeine can accelerate heart rate and lead to irregular heartbeats, especially in those consuming high-caffeine energy drinks. 

Alcohol consumption may temporarily raise the heart rate, potentially causing tachycardia and, if frequent, more severe issues like heart failure and irregular rhythms. 

Smoking makes you breath in carbon monoxide, reducing available oxygen for red blood cells and causing the heart to beat faster to compensate and deliver more oxygen.

Dehydration can also impact the heart rate, leading to problems with blood pressure and body temperature regulation. 

Read More: Is 30 Minutes of Exercise a Day Enough?

While certain medical conditions influence your resting heart rate, you can still take steps to lower it and enhance your overall health if it's higher than normal. Here are a few tips for lowering your resting heart rate:

• Get more exercise

• Reduce stress

• Quit smoking

• Stay hydrated

Read More: Why Walking Might Be One of the Best Exercises For Health

Tracking heart rates over time can be beneficial because it might give caregivers additional insights into their patients’ lives. Other research has shown that a body fending off an infection, for example, or worsening asthma might result in a slight uptick in heart rate over a few weeks.

In the future, tracking those minute changes over time might help alert doctors to what their patients are dealing with. For example, a fertility tracker could potentially be based off daily heart rate changes, Quer says, though it would take a lot more research to make that happen. 

The data from a Fit Bit device could help users monitor their heart rate for any inconsistencies. If it’s possible to track someone’s heart rate continuously, then slight fluctuations in their individual pattern would reveal more about their well-being, said paper co-author Giorgio Quer, an artificial intelligence researcher at The Scripps Research Institute, in an email.

“Instead of focusing on a single measurement done in the clinic, it is now possible to have a longitudinal view of the changes in resting heart rate," Quer said. "As we learn more, [regular heart rate monitoring could] provide information not only for cardiovascular health but also for pulmonary status, early infectious disease detection, reproductive health, and likely much more."

There are a few limitations to the 2020 health rate study. Data from FitBits alone leaves out parts of the population that don’t have the device. It's possible those who wear FitBits might look different from the population as a whole — they might exercise more, for example, or eat better diets.

Additionally, the team didn’t factor physical activity into their analysis. But Quer plans to dive into more of this data — even as he keeps his eye on his own. Quer said he wears two activity trackers 24/7 for a read on his own heart rate, sleep and activity levels.

“For me, it is a great way to understand what is affecting me," he said.

Read More: When Hearts Beat as One

Your resting heart rate could be high due to a wide range of factors. Physical activity and exercise have the potential to alter your heart rate. Moreover, underlying medical conditions, such as asthma or elevated blood sugar linked to diabetes can have an impact on heart rate. Certain substances, like caffeine and alcohol, are known to induce variations. Additionally, dehydration and smoking might also play a role in heart rate fluctuations.

The connection between heart rate and blood pressure varies depending on the specific location within the body. While there is a reverse relationship between heart rate and central blood pressure, there is a positive correlation between heart rate and peripheral blood pressure.

Exercise has a notable effect on heart rate, particularly the resting heart rate. For example, both endurance sports and yoga can lead to a reduction in RHR, which can be beneficial for individuals with high RHRs.

Yes, there is an established connection between high blood sugar and heart rate. Healthy adults with high resting heart rates in the Atherosclerosis Risk in Communities Study, had a 60 percent greater risk of developing diabetes than those with low resting heart rates.

Yes, dehydration can affect heart rate. Mild dehydration can also lead to issues related to blood pressure and body temperature regulation. To address mild dehydration, it is recommended to consume non-alcoholic and non-caffeinated fluids, such as water, sports drinks, fruit juices, tea, and non-caffeinated soda.

The consumption of alcohol can result in a temporary increase in your heart rate. If it surpasses 100 beats per minute, it may trigger a condition known as tachycardia. Experiencing frequent episodes of tachycardia could potentially lead to more severe problems, such as heart failure or the development of irregular heart rhythms, which in turn can increase the risk of heart attack and stroke.

Consuming high levels of caffeine can accelerate your heart rate. In some cases this can result in irregular heartbeat patterns like atrial fibrillation, particularly in individuals who consume energy drinks with exceptionally high caffeine content. Nevertheless, it's important to note that not everyone experiences these effects, and even individuals with underlying heart conditions may tolerate substantial caffeine intake without negative consequences.

Yes, asthma can increase your heart rate for a few reasons. When you have low oxygen or too much carbon dioxide in your body, it can make your heart rate go up. Also, the stress from having an asthma attack can also make your heart beat faster. Finally, the medicine you use to treat asthma, called beta-2 agonists, can also affect your heart rate.

Smoking can increase your heart rate. If you are a smoker, you breathe in carbon monoxide, which reduces the amount of oxygen available for your red blood cells to transport throughout the body. This results in your heart getting less oxygen to pump to the body, which causes your heart to beat faster so you can get more oxygen.

Read More: How Video Games Can Impact Your Heart Health

This article was originally published on Feb. 6, 2020 and has since been updated with information and an FAQ.