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Study Yields Surprising Results About Normal Resting Heart Rate Variability

July 16, 2020

If your resting heart rate (and heart rate variability) seem a little lower this month, there’s a reason why. A recent study found that resting heart rate tends to be lower in July. The findings are important because variations in your resting heart rate may be the first sign of an early unexpected change to your heart health.

Another important piece to come out of this study is that researchers used wearables to track changes in heart rate. Wearable technology in healthcare includes electronic devices like Fitbits and smartwatches that are designed to collect the data of the users' personal health and exercise.

So, let’s take a look at the study, what the researchers did, what they found, and why this is important to you.

Difference Between Heart Rate and Heart Rate Variability

Generally, a low heart rate variability (HRV), or less variability in the heartbeats, indicates that your body is under stress from exercise, psychological events or other internal or external stressors.

Higher HRV (or greater variability between heartbeats) usually means that the body has a strong ability to tolerate stress or is strongly recovering from prior accumulated stress.

And unlike your heart rate, which you can calculate by counting your pulse, heart rate variability is measured at the doctor's office with an electrocardiogram (ECG or EKG) test that records the electrical activity of your heart.

These findings suggest the potential value of further research to investigate whether tracking a person's daily resting heart rate could enable earlier detection of clinically important changes.

What The Study Found

This is the largest study of its kind to date and the results are in the journal PLOS ONE.

Researchers at the Scripps Research Translational Institute in La Jolla, CA, analyzed heart rate data they received from the wearables of 92,457 people. The participants wore the devices for an average of 320 days. Nearly 33 million days' worth of heart rate data were collected in total. The researchers used the data to examine variations in resting heart rate for individuals over time, as well as between individuals with different characteristics.

The analysis showed that one person's mean daily resting heart rate may differ by up to 70 beats per minute from another person's normal rate. They even took into account things like age, sex, body mass index (BMI), and average daily sleep duration, but it accounted for less than 10% of the observed variation between individuals.

The authors also observed a small seasonal trend in the resting heart rate, with slightly higher values observed in January and slightly lower values in July. The researchers also found that some individuals may occasionally experience brief periods when their resting heart rate differs by 10 or more beats per minute from their normal range.

Why Is This Important?

The findings are important because day-to-day changes in your resting heart rate could be the first true, individualized digital vital sign. Similar to a change in blood pressure, a significant change in heart rate may be a sign something is wrong. The study’s lead author said, “These variations in resting heart rate may allow for the identification of early unexpected changes in an individuals' health.”

And this is only now possible to measure thanks to wearable sensor technologies that act as heart rate monitors.

Track Your Resting Heart Rate

If you’re wearing a device that measures your heart rate each day, pay attention to what it’s telling you. Consider it your own HRV analysis method.

You have the power to use your HRV data to help keep track of your overall health. You can talk to your doctor about which fitness trackers might be right for you, or you can get some good information from a website called Wellocracy. It is run by the Center for Connected Health and provides tools and information to help you find apps and personal fitness trackers that suit your personal needs and motivational style. Always talk to your doctor before starting any exercise regimen.

Your fitness app can become a powerful tool. In addition to watching your heart rate, you can use it to count your steps, track your nutrition, and even monitor how much sleep you’re getting.

Taking care of your heart should be a top priority. And there are other, more detailed tests you can have done that are minimally invasive and provide a lot of great information. If you’d like to learn more about these tests that will keep your heart healthy, download our guide, “Cardiology Tests That Are Keeping Hearts Healthy.” In addition to learning about other types of tests, you’ll find information about your risk of having a heart attack within the next 10 years.

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