Put your wearable to work! Learn how to use the metrics your wearable device provides to monitor your stress, influence your recovery, and customize your workouts.

Wearable devices are now commonplace in just about every active population. When I say wearable devices, I’m talking about technology like Fitbits, Whoop Bands, Oura Rings, and dozens of other pieces of technology designed to provide insights into your training, health, and recovery.

This technology has taken off, but the bodybuilding and strength training crowds seem to be among the last active populations to adopt and embrace them on a large scale. I think this is a mistake. A wearable device can provide you with the knowledge to monitor your stress and recovery, and therefore help you make decisions such as how hard you should train. However, even among those who have a wearable device, often they’re not using them to enhance their workout program.

Despite their popularity, most owners of a wearable device don’t understand what to do with all the information it provides for them. Even if they do understand what all the metrics mean, how do they use the metrics to make changes that ultimately help them make progress in the gym? That’s what we’re going to touch on today. In particular, we’ll focus on one metric that I think provides immediate insights that can help you shift your training.

Why You Should Bring Awareness to Your Wearable

As an avid gym-goer, I’m sure you’re familiar with counting macros. Every single one of the top bodybuilders and physique competitors weighs their food and measure their daily macronutrient breakdown, often to the very gram. Why?

Well, if you’re not aware of how much of what you’re putting into your body, how can you possibly make changes around it? How can you know whether you need to reduce your carbs or up your protein in order to lose those last few pounds of fat if you’re not tracking those in the first place? You can’t.

Your wearable device is helpful for similar reasons with regards to your training load, stress, and recovery. How can you know you’re well-recovered if you don’t have tangible metrics to assess that?

Sure, you can go by how you feel, or how sore you are. These are fine steps. But the next level to dial in your training is to actually monitor your recovery, just as you monitor your nutrition and physique changes.

While there are many metrics that can support this, to start off, I recommend you look at just one: heart rate variability.

What is Heart Rate Variability?

To understand HRV first let’s look at an electrocardiogram, or EKG (also called an ECG).

Now, just to refresh you on what an EKG is, think of Grey’s Anatomy (or any show where someone dies in the hospital). When you hear that *beep* *beep* sound it signals a heartbeat, and then when it flatlines, it means they’re dead.

EKG printout

That graph gives us a reading of the electrical activity in someone’s heart, and therefore, their heart rate. In a normal, healthy (not dying) person’s EKG, those high points on an EKG are what we call the “R wave.” When you look at an EKG graph closely, you can see that there’s a difference in time between these R waves, and therefore, a difference in time in between the heartbeats. 

So let’s say for example there were 600 milliseconds in between two heartbeats, 710 seconds between the next, and 650 before the next as we can see by the R waves. But then 710 milliseconds passed between that heartbeat and the next one. Then 820 milliseconds, then 610.

To find out the HRV, we’d look at the average difference between each of those. Now, it's a bit more complicated than this mathematically, and it involves square roots and you don’t really need to know. On a conceptual level, understand that when you’re looking at your wearable device, your HRV score is the average of all your heartbeats taken together over the course of a given time period.

The HRV Your Wearable Device Measures

Now, HRV can be taken at any point in the day. Exercise physiologists, scientists, and strength coaches use HRV from different times for different purposes. On your wearable device, the daily HRV score you see is pulled while you sleep. With the HRV from sleep, your heart rate isn’t changing, or changing as much, as it does when you’re awake and walking about. Your activity is a controlled variable. That means that changes in the heart rate, and the heart rate variability, reflect how efficiently your heart is responding to subtle changes. Looking at your wearable device, a higher HRV score signals that you’re well-recovered.

Related: Sleep Science: Nature's Most Effective Performance Enhancer

Why Does a Higher HRV Mean You’re More Recovered

This may come as breaking news to some of us, but our heart beats without us thinking about it. Crazy stuff, I know. This means that it’s controlled by our autonomic nervous system, which is the part of our nervous system that controls functions that require no conscious attention.

Understanding The Autonomic Nervous System

Within the autonomic nervous system, there are two branches: the sympathetic nervous system and the parasympathetic nervous system.

Now you might be thinking the sympathetic must be nice, kind, easy light. And parasympathetic must be the opposite. Well, you’d actually be completely wrong.

The parasympathetic nervous system is colloquially called the “rest and digest” part of the autonomic nervous system. It calms us down and slows our heartbeat.

The sympathetic nervous system is responsible for the “fight or flight” mechanisms in our body that allow our heartbeat to rapidly increase so we can get blood and oxygen to our muscles in case we get attacked by a lion (or while training in the gym).

When our parasympathetic nervous system is more dominant, our heart rate at rest will be lower. Then, when your heart rate increases because of increased oxygen demands, the rise will be greater, and you’ll have an overall higher HRV. A higher HRV, then, signals that the parasympathetic branch is more dominant and you’re well-recovered.

Now, there are exceptions to this. But for the vast majority of trainees, the exceptions might only matter after they first learn the general trends. Understanding that in most instances a higher HRV corresponds to enhanced readiness and vice versa is a simple benchmark and framework they can use to take action on.

Close up of man checking his smart watch.

What Makes Looking at HRV on Your Wearable So Valuable

Even when you can’t detect changes in your stress and recovery, your autonomic nervous system can, and one of the clearest ways this is reflected in is your HRV. In other words, HRV is a very “touchy” metric.

For example, before you get sick, your HRV might take a noticeable hit. Your immune system is under attack, and that’s adding stress which will ultimately show up in your HRV. If you listen to your HRV score and back off and focus on sleep and recovery, you can halt or blunt the effects of that sickness.

This, in a nutshell, is what makes HRV so powerful. You can get a deeper look into your body’s stress and recovery beyond what we can physically feel. It’s like getting to talk to the unconscious part of your brain: the autonomic nervous system.

Now, let’s get into the factors that can influence your HRV. Knowing and understanding these factors, you can evaluate which levers are out of sync and need to be pulled at any given time. All of the factors can be divided into three categories: training, lifestyle, and biological.

Factors That Affect HRV

Training Factors:

  • Volume: That could be how many sets and reps you're doing, how much cardio you're doing, et cetera.
  • Intensity: If you’re doing the same amount of work in a shorter time, that’s much more intense and will put a greater demand on your body. It could be increased speed, less reps, or more weight lifted.
  • New Stimulus: If you’re adding something into your training you haven’t done before. It could be a new regiment entirely or maybe just some new exercises. Either way, it could add stress to your system.
  • Frequency: If you add in an extra workout day, or eliminate a rest day.

When you increase any of the following, you can expect your body to have a dip in HRV, but then after some time it will adapt to it, and your HRV will come back up. You can also use your HRV score to assess how, or how quickly, your body is adapting to a new stimulus. If, for example, you go from training three days per week to four, you can see how that affects your HRV and how long it takes to go back to your baseline HRV. Once you’re at your baseline, you can then add another new training stimulus to keep challenging your body and make continual progress.

Lifestyle Factors:

  • Diet: Unhealthy foods can stress your body.
  • Hydration: Our bodies are made up of mostly water. So if you’re dehydrated, your body stops functioning at its highest level.
  • Alcohol: Alcohol, which dehydrates you, will do the same.
  • Stress: If you’re stressed outside of training, that will create a sympathetic nervous system response.
  • Sleep: Not much needs to be said here that hasn’t been said before.

Biological Factors:

  • Age: The older we get, generally, the lower our HRV will be.
  • Gender: Males typically have a higher HRV than females.
  • Health Conditions: Illnesses and chronic diseases can have variations in our HRV.
  • Genetics: Other extraneous genetic factors.

Looking at all these factors might be overwhelming. But actually, it should be empowering. If your HRV goes down, that doesn't mean your sleep is messed up or your training volume is too high, necessarily. Rather, it’s made up of a multitude of factors that all form the puzzle that is your health and performance.

Woman doing battle ropes in gym setting with man cheering her on.

How Managing Your HRV Enhances Your Training

The tendency here may be to ask “how do I improve my HRV?” But we don’t necessarily want the HRV number to stay high. In fact, training should and will cause a bump down in your HRV. But having the data can help you add in the right amount of stimulus and gauge how it’s affecting your autonomic nervous system. You can add just enough new training to spur stress and ultimately adaptation but not so much that it sets you back. This is where the knowledge of your HRV provides key insights into your training.

For example, if your HRV is higher than normal, consider adding more volume to your training since you’re well-rested, and vice versa. Rather than just following the standard training schedule week after week, tailor your schedule to what your body is telling you it can handle.

However, if you haven’t added stress to your training, but you’re noticing it decreasing, that’s the time to look at other factors like lifestyle factors to assess what could be signaling a sympathetic response in your autonomic nervous system. Check the simple boxes first. Are you hydrated? Sleeping and eating well? See if those bring your HRV back to baseline first.

Regardless of the variables you change, understanding HRV gives you the awareness to understand your body better, to become more in tune with its subconscious messages and adjustments.

This is the power of a wearable device. It brings attention to elements of your training and recovery you would otherwise and allows you to dial your training in so you can optimize your workload and recovery.