Tracking your Heart rate variability (HRV) may be what you are missing in order to prevent overtraining, maximize your fitness, and improve your overall health.
There are a lot of things out there that say they help with “recovery”, but how do you know if they actually do? Well, Heart-Rate Variability (or your HRV) can give you a lot of insight into your training, recovery, and overall fitness.
What is it?
Your HRV is the average difference between beat to beat of your heart. If your heart rate is 60 beats per minute, its not actually beating at exactly 60 bpm (check the image on the right to see what I mean). The 60 bpm is actually more like the average heart rate. These little differences is the heart rate variability.
Why does it matter?
The more variability we have between our heartbeats, the healthier we are (generally). Your heart rate is regulated by 2 different branches of your autonomic nervous system (the part that controls the things you don’t have to consciously think about doing like breathing, hormone release, digestion):
Sympathetic: the fight or flight side. This typically drives a higher heart rate, as it is focused on driving blood to your muscles and brain, burning energy to supply the muscles and brain. Think about how fast you could run if you were running from a bear. That’s because your sympathetic nervous system is driving blood to your muscles, and is completely ignoring digesting your lunch or repairing tissues at that time.
Parasympathetic: the rest and digest side. This side is driving a lower heart rate. It’s focused on driving blood towards internal organs, for digesting food, shuttling nutrients, and repairing tissues. This is the side we want in control when we are sleeping or laying on the couch.
So, your HRV is the balance between these two sides, and the reason you want a high variance, is because that means that you are adaptable. Ready for whatever life throws at you. If a tiger jumps out of your closet, you should be able to quickly shift into fight or flight mode in order to run for your lift (or fight it I guess, but I’d let you do that as I ran away). If you are lounging on the couch, you want to be more parasympathetic, repairing tissues and digesting food. When you have a low HRV, it typically means that one side of your nervous system is behind the wheel (typically the fight or flight side). That means your body isn’t focused on digestion, repairing tissues, or building up its energy stores. Not exactly ideal when you are trying to build up muscle tissues after training, or recovering from an injury.
What effects it?
There are a lot of things that can have an effect on your HRV. Some examples:
If you train extra hard today, or for a few days in a row, your HRV will start to take a hit and be reduced.
If you are getting reduced sleep for several days in a row, your body will begin to think that you are staying awake to protect yourself from something, meaning a reduced HRV as your fight or flight nervous system kicks in.
Alcohol will reduce your HRV for up to 5 days afterwards, even if you only have 1-2 beers/glasses of wine. This is most likely due to effect that alcohol has on sleep.
Poor nutrition reduces HRV because your body will switch to survival mode (fight or flight) due to a lack of proper nutrients to repair tissues, etc.
How do we use it?
Your daily HRV by itself isn’t very helpful, because while there are age norms, HRV will be highly individualized. Everybody is different, has different training, lifestyles, diets, etc. So, instead of reading into the single number too much, you should be looking at the general trends. This means that you need to consistently be tracking it over time in order to see these trends. You don't want to see huge dips, but you don’t want to see huge spikes either.
If your HRV is trending downwards, it may mean that you are wore down from stress, excessive training, poor sleep/diet. When you see this happen, it may be a good idea to dial back the training a little bit, prioritize sleep, and make sure that you are controlling stress as much as possible. If you are seeing HRV trend upwards, that is good! That means that you are improving your health (as long as it is not a huge spike upwards).
You can see this graph below has a general trend upwards over time.
Generally want to include more data than just HRV. Things like type of training, training volume, training intensity, hours of sleep, do you feel rested? Do you feel mentally there or kinda spaced out? Did you have any alcohol yesterday/last night? Do you plan on training today? Are you excited about training today? How stressed are you right now? The more data associated with the actual HRV number itself, the better. But more on that in a second.
How do you measure it?
Your HRV should be measured in as controlled of an environment as you can make it. That is to help make sure that you avoid outside factors that may change the number. The easiest way to do this is to just measure it immediately upon waking up. Right when you get out of bed, pre-coffee, no walking around.
Most fitness trackers have a way of measuring HRV (fitbits and apple watches), but if they are older models it may not be a very good measure, as the heart rate sensors aren’t exactly perfect in older models. You can measure your HRV via the breathe app on apple watches. You just have to sit quietly for a minute, follow the prompts, and then you will be able to check your HRV in the health app.
The Whoop band is a standalone wearable. You wear it 24/7, it takes a bajillion data points per second, tracks your sleep, etc. You even charge it while wearing it. Really cool because it can give you insight into how much sleep you need in order to perform how you want to perform the following day, how much sleep debt you have, etc. This is nice because you don’t have to actually sit down and measure like you do with the apple watch, because it is always tracking it. It is an amazing piece of technology. When you sign up, you basically get the band for free, and you pay a monthly fee for access to your data and things. So it is actually fairly affordable.
The Whoop band is a standalone wearable. You wear it 24/7, it takes a bajillion data points per second, tracks your sleep, etc. You even charge it while wearing it. Really cool because it can give you insight into how much sleep you need in order to perform how you want to perform the following day, how much sleep debt you have, etc. This is nice because you don’t have to actually sit down and measure like you do with the apple watch, because it is always tracking it. It is an amazing piece of technology. When you sign up, you basically get the band for free, and you pay a monthly fee for access to your data and things. So it is actually fairly affordable.
In conclusion
I highly recommend you track your HRV somehow. If you’re looking to be more healthy and get more active, it’s a great way to track your health and recovery over time. It’s a great way to keep yourself in check to prevent overtraining, which may lead to injuries. I’ve even had times where I’ve seen my HRV decreasing over the course of four or five days, and I didn’t know why (I felt fine), and then I got sick. So my body was fighting off the sickness before I even knew it. If you listen to your HRV, you can help yourself by prioritizing sleep and nutrition during that time.
You have to remember that the HRV is just one piece of the puzzle. So a lower HRV than normal one day doesn’t mean you can’t still push hard that day. Like I said, the trends are really what matters and what can really give you a big look into how well you were actually handling the amount of training you’re doing, or how well you’re recovering from an injury, etc.
If you want to learn more about HRV and how you could use it, I highly recommend checking out the blogs of Whoop and HRV4Training.
If you have any questions, please feel free to reach out. I’d love to try and answer any questions you may have!
Thanks for reading!
Jacob Erbes PT, DPT, CMFA, CF-L1