ISLAMABAD-A recent study concludes that when it comes to resting heart rate (RHR), “normal” does not exist. Although most people’s RHR is relatively stable over time, from person to person, rates vary by as much as 70 beats per minute (bpm).

RHR is easy to measure, but what does it mean for our health?

Although doctors routinely measure people’s RHR, it is still not clear what constitutes “normal,” and what variations from this norm mean for health.

Over the years, large studies have come to a consensus on what doctors should now consider the normal range.

For instance, the National Health and Nutrition Examination Survey, which analysed data from almost 50,000 people, found that the average RHR for adults is 72 bpm.

The American Heart Association (AHA) considers an RHR of 60–100 bpm normal for adults.

However, RHRs that fall well within the normal range can still increase a person’s mortality risk.

Why does RHR matter?

Today, wearable sensors mean that it is possible to take accurate heart rate measurements continuously. Alongside monitoring heart rate each second, this technology also records sleep duration and levels of activity.

As the study authors explain, the popularity of these sensors provides a “unique opportunity to better understand how RHR varies over time for and between individuals over the span of days, weeks, years, and, eventually, lifetimes.”

If these all-pervasive wearable sensors can pre-empt the onset of disease, this would make a significant impact on healthcare at a population level. For this reason, it is vital to understand what information heart rate can provide.

If we can decode the secret messages that our hearts tap out, we could continuously monitor our health and, potentially, receive advanced health warnings.

The researchers had access to data from 92,457 adults across 50 states. Each participant wore a heart rate monitor for at least two days each week for at least 35 weeks between March 2016 and February 2018. Each day, they wore it for at least 20 hours.

In total, these data provided 33 million daily RHR values.

Overall, the average RHR was 65.5 bpm plus or minus 7.7. The minimum and maximum RHRs for each individual were 39.7 and 108.6 bpm, respectively. In other words, between individuals, “normal” could vary by around 70 bpm.