What Heart Rate Variability (HRV) Means for Our Health and Longevity
You might not have heard of heart rate variability, but it’s one of the best ways of measuring your overall heart health. In this post we’ll break down what HRV is, what factors affect it, and how to improve your HRV and support your heart.
What is Heart Rate Variability (HRV)?
HRV is a measure of the difference in time between the beats of your heart. If you have a resting heart rate of 60 beats per minute, that doesn’t mean that your heart beats once every second. Instead your heart might beat at 0.9 seconds, then 1.4 seconds, then 1.1 seconds, and so on. HRV records the variability between beats, the difference between the shortest and the longest beat.
How is HRV calculated?
Your HRV measurement is the result of a complex calculation called the root mean square of successive differences. Say that three times fast!
To find your HRV, the calculation takes a series of measurements of time between heartbeats. Then it squares all those numbers and calculates the mean, or average, of the squares. The final step is to calculate the square root of the mean, and that’s your HRV.
The result is close to the average amount of time between the longest and shortest heart beat, measured in milliseconds. But taking the extra steps to find the root mean square of successive differences (or RMSSD) makes your HRV measurement even more accurate. This helps pick up subtle changes that can indicate how your heart is responding to various inputs.
What inputs affect heart rate variability?
Our heartbeat is controlled by the nervous system. There are two different input types that can make your heart beat faster or slower. The sympathetic system responds to stimulus like exercise, fear, or stress. When it detects these “fight or flight” moments, it releases hormones that increase heart rate. This is so you have more energy to deal with the stimulus.
The second branch of the nervous system that affects your heart is the parasympathetic system. This branch focuses on internal signals like how much food you’ve eaten, or if you’re getting over a cold. It releases hormones that slow down your heart rate.
We can override these systems through our behavior. For instance when we drink caffeine it will raise our heart rate, or taking the sleep aid melatonin reduces it. And although exercise initially increases our heart rate, regular cardiovascular exercise will result in an overall slower heartbeat.
What is considered good heart rate variability?
Unfortunately, there’s no simple answer to if your HRV is good or bad. For starters, your HRV measurement is only a snapshot of how your heart is performing at a single moment in time. So many factors affect heart rate variability that it never stays the same for long! As well as what you eat and drink, how much you exercise, and your general stress level, many other things can affect your HRV. These include your overall health, age, gender, genetics, and much more.
Generally speaking, younger, healthier people have a higher HRV than older or less fit people. At 25 years old, you could have a HRV of 100ms or more, but by the time you reach 65, a HRV of 50ms is considered high. The higher your HRV, the healthier and more responsive your heart is to new stimuli.
One thing you may notice if you start monitoring your HRV is how long the after-effects of different activities can last. Simply having a few glasses of wine with dinner can lower your HRV for the next 3-4 days!
Because of all these variables, what really matters isn’t one particular HRV score, but the overall trend of your HRV. Paying attention to what increases or decreases your heart rate variability can help you manage your diet and lifestyle and support your heart’s health.
How to improve your HRV
The good news is, the factors that affect your heart rate variability (and heart health in general) are things you probably already know. Maintaining a healthy weight, eating a balanced diet, and reducing your intake of alcohol, caffeine, and similar substances, will do wonders for your heart.
You can also improve your HRV by working smarter, not harder. Train intelligently — don’t overdo it. Your heart is a muscle, and it needs time to grow and respond to different activity levels. If you work it too hard and never give your body time to rebuild and recover, you’ll end up doing more harm than good.
Keeping a regular routine also helps. Get enough sleep at night, go to bed and wake up at the same time each day, and stick to regular mealtimes. That midnight snack might be delicious, but your heart will still be feeling the effects from it long after the taste has faded.
What HRV means for longevity
There are many ways to monitor how we’re aging. From our ability to run a 10-minute mile to our BMI, our bodies and lifestyles give us clues to if we’re aging faster or slower than our peers. However many of these methods are highly subjective. For example bodybuilders and elite athletes can be incredibly fit, even if their BMI scores say they’re obese.
HRV may be one marker that tells us more about how we’re aging than other tests we can take. Aging is associated with decreased HRV function, which suggests a link between HRV and longevity. One study of HRV measurements in a large group of healthy individuals aged 10-99 found that a “persistently high” heart rate variability was an accurate predictor of how long a subject would live.
Even more specifically, what heart rate variability measures is something called autonomic function. That means all the everyday bodily functions that we don’t consciously control. They include our heart rate, breathing, digestion, and blood flow. These activities are regulated by our nervous system so we never, for example, forget to breathe. Our bodies just do it automatically.
The latest science suggests that autonomic function goes hand-in-hand with longevity. And while there’s still a lot of research to do on how exactly that works, we can measure the effects right now by monitoring our HRV.
Heart rate variability is a fantastic tool for measuring how your heart responds to different inputs, and what that means for your heart’s health. Many smart wearables on the market now offer HRV monitoring, making it easier than ever before to see how your heart is doing. And because your heart rate variability is a measure of your body’s autonomic functions, HRV could also give you a direct insight into your longevity and how you’re aging on the inside.