The One Biometric You Should Track to Optimize Health

You’re missing one important measurement.

Biometric tracking is huge these days. We measure everything: our sleep, our calories, our water intake, our exercise. I think we can pretty much track anything, and if we can’t, it’s coming in the next iOS update.

But did you know there is one biometric that is particularly important to pay attention to, as a window into the overall health of our entire body? And this biometric needs to be tracked every day, at the same time and in the same environment.

Let me introduce you to heart rate variability (HRV).

I recently became interested in HRV when my Apple Watch was telling me that mine wasn’t good. I didn’t even know what HRV was. I didn’t know if it should be high or low. I had no idea what it was telling me. But a score of 1 star out of 5 surely can’t be good.

But HRV is something you should be aware of. It can provide meaningful insights into the state of your body and your wellbeing in general. It provides clues as to how you are doing, and it’s vital that you pay attention.

What is HRV?

HRV is the variance in time between heartbeats. Interestingly, the heart doesn’t beat at a constant rate. The greater this variability, the more “ready” you are to perform at a high level - whether cognitively, physically, or socially. In essence, high HRV is good, low HRV is not so good.

While HRV is a direct representation of your heart rate, it actually manifests in the nervous system. It comes from the competition between your sympathetic (fight or flight) and parasympathetic (rest and digest) nervous systems.

“If your nervous system is balanced, your heart is constantly being told to beat slower by your parasympathetic system, and beat faster by your sympathetic system. This causes a fluctuation in your heart rate: HRV.” — Mark van Deusen, WHOOP

HRV is an indication of whole-body health

HRV has been used the most in sport and fitness, as it as an accurate portrayal of recovery and training adaptation. It can also tell athletes how hard they can push that day and still recover effectively and see results. However, it is starting to be used more and more as an indication of whole-body health in both athletic and non-athletic populations. HRV is a useful biometric for everyone to be aware of.

High HRV means that your body is able to respond to both sympathetic and parasympathetic information, thus portraying that your nervous system as a whole is balanced, and you’re able to respond to your environment effectively.

Low HRV means that either the parasympathetic or sympathetic nervous system has more control over you. It means that your body is working extra hard, maybe because of fatigue, dehydration, stress, or sickness. This is where the readiness concept comes from: if your body is busy dealing with stress or sickness, you have fewer resources left for athletic or cognitive performance.

“Measuring your HRV is one of the best ways to know if your body is stressed.” — Ben Greenfield, health and fitness expert.

This is why it is so important to track your daily HRV. You will be able to see trends and to correlate them with what is going on in your life. If you can see what your body responds badly to, you can change it. Conversely, if you see that your HRV is decreasing, you’ll know that your body is unhappy even if you weren’t consciously aware of it. Ben Greenfield calls HRV a “window into your nervous system and subsequently your stress response.”

What is a good score?

Consistent, rather than “high”, is more important when looking at HRV, as stability is important with any health parameter. Your HRV trend will provide you with a more accurate picture of what is going on than your actual score. It’s important to pay attention when you notice a downwards trend.

HRV varies greatly between people. It tends to be higher in younger people and very high in elite athletes, especially endurance athletes. Genetics, health, and environment can also impact it, so it’s really hard to determine what a “good” score is.

When should you measure it?

Measure HRV first thing in the morning. An Apple Watch can accurately measure HRV, especially when used in conjunction with the Breathe app. But devices such as the WHOOP strap and the Oura Ring are also very accurate tools to measure HRV.

Measuring first thing in the morning will give you the most meaningful score. The nervous systems are easily affected by things during the day, such as food, stress, caffeine, etc, and so taking a measurement during the day will not provide an accurate score of what is going on. Incorporating this measurement into your morning routine would be highly beneficial.

How do you improve HRV?

Rather than focusing on improving your number, focus on learning how to better modulate both branches of your autonomic nervous system (sympathetic and parasympathetic systems). Modulating your nervous system is a skill that can be learned, which will directly impact your HRV score.

“In order to modulate HRV, you must become more self-aware.” — Ben Greenfield

In the days of our ancestors, stress included being chased by predatory animals, and maybe sometimes other tribes of people. We had to fight or flee, and our lives were in danger. These days, stress is usually non-life-threatening. A report due at work, bills to pay, a long to-do list. While very stressful, they’re not going to kill you. But they’re having a huge impact on your HRV because your body thinks your life is in danger.

So what can you do? You need to communicate to yourself that you’re safe, in order to turn down the volume of your sympathetic nervous system and restore some balance.

A great way to achieve this is through breathwork. We don’t breathe well anymore. We often breathe shallowly and through our mouths. Both of these actually stimulate the sympathetic nervous system, therefore increasing stress. Breathing properly is so important.

In fact, I even recognized this fact when I was 16 years old. I bought a book about breathing, and I made it my summer holiday mission to learn how to breathe properly.

Simply breathing through your nose, and ensuring your stomach, rather than your chest, is rising, will be incredibly powerful for modulating your nervous system.

This will communicate to your brain that you are safe. As you continue doing this regularly, you actually change your autonomic response. Your body begins to be better able to modulate your fight or flight responses to stress and you will be better able to move in and out of this state at will.

The following are further methods to improve HRV.

• Make sure you’re getting enough rest — from both training and life. Strenuous activity (physical and mental) is taxing on the body and increases systemic stress.
• Stay hydrated. Dehydration is stressful for the body.
• Limit alcohol. Alcohol is also a stressor on the body, so don’t go overboard. Alcohol can lower your HRV for up to 5 days.
• Eat nutritious foods. Nutrition supports all functions of the body. If these are not able to operate properly, your body will experience stress and inflammation.
• Eat enough food. While nutrition is very important, eating enough is just as important. Being hungry is stressful for the body and induces a stress response, therefore activating your fight or flight system.
• Get good quality sleep. Sleep helps with mental and physical recovery. Without it, your body is going to be stressed.

Some more geeky ways to improve HRV:

• Cold exposure. Either cold showers, ice baths, or cold plunges, cold exposure reduces inflammation and enhances recovery.
• Adaptogens. An adaptogen is a natural substance that helps your body adapt to stress and return to, or maintain, baseline physiological levels. Essentially, they help you deal with stress, which we now know is very important for HRV.
• Meditation and yoga. These are powerful techniques for down regulating the sympathetic nervous system.
• Grounding. Placing your bare feet on the earth allows the negative ions produced by cellular metabolism in your body to be absorbed by the earth, as a result of the earth’s magnetic field. This reduces inflammation in the body.

We’re getting worse and worse at listening to our bodies these days, but HRV is an important and straightforward indication of how you are, really.

HRV will tell you if you are stressed if your body is coping with your current lifestyle, and whether or not you are recovering from exercise. Tracking your HRV is probably the most important thing you can do to monitor your whole-body health.

While downward trends indicate that something is wrong, you can improve your score with breathwork, eating and sleeping well, recovering effectively, and staying hydrated.