SS 277 – Heart Rate Variability (HRV): Should You Care?

Episode 277 Show Notes


Grant and Heavey tackle heart rate variability (HRV) – why it’s important, the mechanism behind it, and how to best use it.

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[06:30] What is HRV?

If your heart has 60 beats per minute, that’s 1 beat per second.  You might assume that’s beating precisely on every second. But there’s a beat to beat variation that is measured to come up with your heart rate variability.

So if the first beat is at 0.0 and the next beat is at 0.001 sec. So you’re given this couple millisecond variation every single time your heart is beating.  How is this information useful to us?  

[08:05] The Autonomic Nervous System: The Sympathetic

There are two branches of the autonomic nervous system: the sympathetic and the parasympathetic. The sympathetic is what people refer to as the fight or flight system. The parasympathetic is also referred to as “rest and recover” or “rest and digest.”

Example of the sympathetic system:

You’re driving down the street and all of a sudden somebody runs out in front of your car. You slam on the brake and your heart starts pounding. You feel that dose of adrenalin. 

Benefits of the sympathetic system:

Increase in heart rate and blood pressure

The body diverts blood flow to the muscles.

It drives sugars into the bloodstream to give you more energy to act quickly.

It inhibits digestion.

It reduces appetite.

So when the sympathetic nervous system is dominant, it helps us cope with stressful situations. 

[10:00] The Parasympathetic

The heart rate slows and the blood pressure is decreased. The blood vessels are dilated. It promotes energy storage. It turns up protein synthesis. So if the sympathetic dominance is what happens when we run from the T-Rex or lift a barbell in the gym, the parasympathetic is what we want active when we’re not doing those crazy intense things. So we can recover from them, improve from them, build muscle, and come back stronger and faster the next time around when the sympathetic system becomes dominant.

[11:00] The Correlation Between HRV and the Autonomous Nervous System

There’s a natural variation between beats and the variation shortens when the sympathetic nervous system is dominant and it lengthens when the parasympathetic is dominant.

HRV can be measurable using much more sophisticated equipment than an Apple watch. 

So we know that the branches of the nervous system activate these different areas. And we can see that the lengthening or shortening of heart rate variation also correlates with all these other activities that are consistent with sympathetic or parasympathetic. 

[12:42] HRV in Training

It’s hard to get insight into sympathetic and parasympathetic because they’re always tugging on one another. There are varying levels of activation and dominance of these branches of the nervous system.

The premise of HRV is to provide some quantitative elements to what branch of the nervous system is dominant in your body. 

Having some insight into recovery is so important. It’s really easy to see the training side of things and track how many times you’re lifting weight or what’s your training volume or what your time was on a certain interval. It’s really difficult to get quantitative data on recovery. 

That’s why HRV is exciting because it gives us a promise of giving us quantitative data on recovery. All that being said, the reality of how we use it is not as exciting as the promise. 

Changes in HRV do seem to correlate with changes in performance for activities. You’re continually measuring your HRV over an extended period of time and you’re improving aerobically then you should see an increase in heart rate variability.

Some people try to use HRV as an indicator of their daily performance. But there really hasn’t been good results from studies showing that this makes any sense.

[15:37] The Bogus of Training Apps

It’s the proprietary algorithm of those smartwatches and apps to rate your sleep or whatever. They’re not going to give you an insight into it, plus they’re not going to share the science behind the recommendations they’re making which are mostly bogus anyway. Or they’re driven by the mechanism where we see the promise but the actual results aren’t necessarily consistent with that mechanism.

Grant makes a valid point that it’s kind of silly to throw out the way you’re feeling in favor of some measurement just because the app says you’re ready to train today. 

One of the traits of elite athletes is being super in touch with the way they feel. They have an innate feeling about how prepared they are for exercise on that day. This is what propels them into the levels of performance they achieve. 

[17:49] Sleep App Looking at HRV and Cognitive Function

All of these things have a correlation with HRV but the daily score is not necessarily representative. It’s more of this macro perspective and looking at what’s happening over long periods of time and trends.

Lifters use HRV today and there are many studies that look at the correlation between other markers of recovery such as soreness and creatine kinase levels, etc. But for now, there’s not probably much value for strength athletes, specifically for lifting. 

[20:35] How to Best Use HRV

Consider HRV as a higher-level measurement where you’re not looking at it day-to-day. It’s about macro changes over time. It’s possible to gain greater daily insights in the future as we refine protocols and do more scientific research on it and have better technology. But for now, this is best viewed as a macro-level indicator of nervous function system recovery and so forth.

But for some people, quantifying some of that is a bit of a challenge. It’s invaluable to look at other markers but you shouldn’t hang your hat on them. Just use them as a single marker in the cluster of things.

[23:24] How to Get the Best of Your Measurements

The daily measurements that your devices are creating are not valuable because they are subject to so many other things that are happening. 

The acute measurements are the ones that can be valuable. The devices that are best suited for measuring HRV are the chest straps. The other devices are getting better and we’re getting to the point where some of them can be used for measuring HRV. But we’re still not at that level.

If you want to make sure to get the best measurement possible, use the chest strap along with 5-minute measurement apps on the phone to get your score. Do this at least three times a week under the same conditions. These are all subject to the influence of the nervous system. If you’re moving around at all, this could throw off the measurement. 

We’re talking about milliseconds here for variability. All sorts of activities in the body can influence this so you need to do your best to replicate your measurement environment each time if you want to get any value from the measurements. 

This is also a big factor as to why you have to do this first thing every morning is also a big factor. There’s probably some value to the HRV skew but Heavey definitely won’t bet his life on it.

[27:00] Shoot the Shit: Social Media Minimalism

Not having any internet connection can cause a lot of anxiety for many people. Heavey has been doing this social unplugging once a year where he’d go to a place without any internet. He decided to apply this to his everyday life by not checking his email until 4 pm every day. This has significantly improved the way he feels to not be on those social channels. Even if that’s the case, he’s still able to respond to all of the emails within 24 hours.

Heavey personally thinks many people are deceiving themselves into thinking that they don’t have this luxury when in reality they do. The world will not burn down if you don’t check your email but once a day.

This is one of the changes Heavey has implemented and he’s able to go deeper on the tasks he’s working on. His focus has improved and he feels better and more productive in everything he does. All because there isn’t this nagging thing that has to constantly be up-to-date on his email or his Instagram feed.

He has also turned off notifications on his phone and the only thing he gets is calls. And taking it next step further, he’s thinking about using the Apple watch not to add more technology into his life, but to reduce technology. So he’ll be using his watch as his phone to reduce temptation to check his email or do whatever he normally does on his phone.


 If you like Heavey’s take on health and fitness be sure to subscribe to his weekly emails where he shares current research and his favorite tips and tricks:

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