According to a paper published in the scientific journal Frontiers, heart rate variability (HRV) is linked to “exceptional longevity.”
The metric was also mentioned in Netflix’s Don’t Die, a documentary focusing on Bryan Johnson, a multimillionaire obsessed with living forever, through sometimes-controversial means.
Unusual as the wealthy man’s methods can sometimes be, though, experts seem to think HRV does help to indicate health on a population level, even if many debate its relevance in most medical and personal settings.
Way back in 2010, researchers found that “longevity depends on maintenance of good autonomic function, particularly HRV–PF”, but NHS cardiologists and Harvard Health say it’s unclear whether measuring it on an individual level is actually helpful.
So, what is heart rate variability, and why do some health experts think that measuring it might not be as useful for us as you’d think?
What is heart rate variability?
Heart rate variability (HRV) refers to the variation of time between heartbeats. It is usually measured in milliseconds and requires special equipment to be tracked.
This variation is managed by the autonomic nervous system (ANS), which Harvard Health explains is made up of the “sympathetic and the parasympathetic nervous system, also known as the fight-or-flight mechanism and the relaxation response.”
When you’re stressed, in danger, or exercising, your heart rate is higher, meaning your HRV (the time between beats) is lower. When you are relaxed and healthy, your HRV tends to be lower because your heart rate is slow.
This adaptation can be healthy, as your body has different needs at different times. But, Cleveland Clinic says, sometimes your HRV is not adapting to what’s best for your body because conditions like diabetes, anxiety, and asthma can lead the sympathetic system to put out high heart rate cues too often.
That’s partly why researchers think a high HRV can be an indicator of health and longevity. It can suggest you’re in good health, not too stressed, and getting enough sleep.
So why wouldn’t measuring HRV always be helpful?
So, multiple studies have linked HRV to longevity and health. Why aren’t we all measuring ours as we do blood pressure?
Well, firstly, it’s very difficult to accurately do so; and once you have the results, interpreting them on an individual level is hard.
In medical settings, an electrocardiogram machine (an EKG) is used, though some patients are sent home with monitors. Cleveland Clinic says, “The majority of wrist-worn fitness devices and trackers track your heart rate through your skin. Unfortunately, this means they usually aren’t sensitive enough to detect heart rate variability accurately.”
Dr Malcolm Finaly, a consultant cardiologist and electrophysiologist at Barts Health, said trying to improve your HRV first might be “putting the cart before the horse.
“Instead, it’s a case of improvements in your health can change your HRV. So don’t worry too much about what that number is, and instead focus on getting more exercise and eating well.”
The doctor said the metric can be of “little use” to physicians when assessing and treating patients, as it “offers only a general picture.
“It’s been shown to be a good overall indicator of stress or relaxation levels across large groups, but looking more closely at the individuals, it does not always correlate reliably with people’s real stress or relaxation. To put it another way, you might have a high HRV and still be stressed.”
Harvard Health said there are “questions about the accuracy, reliability and overall usefulness of tracking HRV,” stating that its link to our ANS (which many proponents focus on) needs more research.
So, while the lessons HRV teaches us about managing our stress, staying active, eating well, and getting enough sleep are certainly worthwhile, experts don’t all agree that measuring yours is a worthwhile use of your time, worry, and money.