Heart Rate Variability

Heart Rate Variability
Heart Rate Variability (HRV)

After hearing some ads about the WHOOP fitness tracker, I decided to purchase one.  I mainly wanted to track my sleep with the WHOOP, but found that one of its best functions is how it calculates strain and how well recovered you are. It does this by measuring your heart rate variability (HRV) and resting heart rate (RHR) during your final slow-wave sleep cycle of sleep and feeds that data into an algorithm to generate a personalized recovery score.  Since your HRV is an indicator of how well recovered you are, learning how to improve your HRV will improve your recovery.

What is HRV?

So what exactly is HRV?  Heart rate variability is the variation in time between beats of the heart.  So if you have a heart rate of 60 beats per minute and averaged exactly 1 beat per every second this would result in a low HRV because each beat is exactly happening 1 second after the next.  An example of a high HRV would be having a beat at .95 seconds and then the next one is at 1.2 seconds and so on.  

This may seem counterintuitive, but having a high HRV (i.e. a larger variance in the time between beats) is a sign of a healthy autonomic nervous system.  Your heart receives signals from the vagus nerve which then dictates heart rate.  

Sympathetic vs. Parasympathetic

The autonomic nervous system controls your bodily functions that you have no control over like your heart beating and digestion.  The autonomic nervous system can be further broken down into two different branches: the parasympathetic and the sympathetic nervous system.  The parasympathetic branch is the deactivating side of the nervous system and lowers your heart rate when it receives signals from your organs responsible for digestion (a.k.a the rest and digest part of the nervous system).  The sympathetic nervous branch is the activating portion of the nervous system (a.k.a the fight or flight part of the nervous system). The sympathetic branch is activated by stress or physically arduous things like a HIIT workout.  

These branches of the nervous system are constantly sending signals to the heart via the vagus nerve.  Each branch pulls the heart rate one way or another, which is the reason there is variability in your heart rate.  If we go one step further, having a higher variability shows that you have a healthy functioning and balanced parasympathetic and sympathetic nervous system; one that is ready to respond to a stressful or restful situation at a moment’s notice.  

Applications for this Data

Now that you know what HRV is, how can you use it to make yourself better?  Well, by tracking your HRV over time and getting a good idea of what your baseline is you can start making educated decisions on how you might want to work out that day.  For example, if you now that your HRV is high, you know that your nervous system is primed and has the ability to undertake a hard workout. Have a heavy squat or clean workout planned? Now would be the time to do it.  Maybe your HRV is showing a lower than usual score. This could be a good opportunity for some low-intensity cardio or a good day to work on mobility. What’s great about this is not only will you respond better to the workout, but you can reduce your injury risk.  As a retired division 1 athlete who works in a corporate environment, avoiding injury is of paramount importance.

What Effects HRV?

Lots of factors go into your personal HRV.  Your age, your gender, your environment, and your overall fitness all affect what your HRV will be. 

How to Improve HRV

Here are 5 ways to improve your HRV. 

#1 is hydration. Being properly hydrated is key to basically everything with health and when it comes to HRV it is no different. 

#2. Decrease your alcohol intake. Most know about the deleterious effects of alcohol. It also negatively impacts your HRV.

#3. Resting smartly after a workout.  After a hard workout, it’s important to recover properly.

#4 Your nutrition. Getting poor nutrition will also negatively affect your HRV. And finally,

#5 is sleep. Getting good sleep quality is paramount for enhancing your HRV.  It is not just about the time asleep, but about the quality. I have been experimenting with how my sleep affects my HRV for the last few weeks.  

Experimenting with Sleep and HRV

Besides tracking my HRV, I have also been tracking my sleep.  On a night where I get good quality sleep, my HRV tends to be higher.  How to get good quality sleep is a topic that can be explained in another post at length.  But for now, here are a couple of ways I’ve been able to get a better HRV by tweaking a few things before bed.

Buying a sleep mask like this:

On nights where I wear a sleep mask, I notice a slightly higher HRV value and also a lower resting heart rate.  There are obviously many variables that go into how well your HRV will be the next day so perhaps this isn’t an ironclad way to increase HRV, but for me, it appears to be the reason.  Check out my WHOOP data below and you can see the effects that wearing a sleep mask have had on my heart rate variability.

heart rate variability whoop data
whoop sleep data

I discovered another great sleep hack that is sure to help raise HRV. I read an article about how Cristiano Ronaldo hired a sleep coach for a ridiculous amount of money. One of the tools the sleep coach used to improve Ronaldo’s sleep are… Breathe Right Strips. Breathe Right Strips are membraned plaster strips that open up the nasal passages when attached to the nose. They promote a natural breathing process rather than constantly using the mouth to breathe in and exhale, giving you more chance of keeping the nasal passages open when congested from common cold symptoms. Breathe Right Strips help you breathe from your nose rather than your mouth. Mouth breathing is associated with the stress-inducing sympathetic nervous system whereas nose breathing is associated with the relaxing parasympathetic nervous system. Therefore, Breathe Right Strips are a cheap and easy way to get better sleep and raise your heart rate variability.

Next, is to not eat right before bed; especially crappy foods.  After a night of pigging out on desserts and having a whole box of Cheese-Its right before bed, I saw my HRV plummet.  Like I previously said before, there are many variables that go into your HRV, but it seemed like more than a coincidence that my HRV plummeted as soon as I went to sleep after eating a bunch of garbage.  

Heart Rate Variability Graph
HRV plummeted after a late-night binge on snacks

Another way to improve HRV is to supplement with melatonin. I use the basic over the counter 3mg Nature’s Bounty Melatonin right before bed.  I will sometimes take just one tablet 1 and other nights take 2. The next morning I saw a large spike in my sleep quality; mostly in total REM sleep after taking 6mg of melatonin.  This elevated my heart rate variability and I really felt great the next day.  

Some studies have shown that 3mg of melatonin is a much larger dose than what your body makes naturally. ”Serum melatonin concentrations observed after the 0.1- and 0.3-mg doses were within the normal dynamic range for nocturnal melatonin concentrations…. These results indicate that ingestion of an acute dose of melatonin, sufficient to increase circulating melatonin to levels within the normal nocturnal physiologic range, has hypnotic effects.”(1)  This means that a lower dose of melatonin in the .1-.3 mg range is effective at promoting sleep.

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