Heart Rate Variability, The Number One Performance Marker You Should Be Measuring
Heart Rate Variability
The Number One Performance Marker You Should Be Measuring
When it comes to health and fitness, people have founda myriad of ways to quantify their performance. From measuring your heart rate zones during exercise to measuring blood sugar responses to food, there are hundreds of ways to measure your success, and in the words of Peter Drucker: “What gets measured, gets managed.”
With all that said, one of the newest forms of measuring health is through a marker called heart-rate variability (HRV). You may have heard of it, but if not, then here’s why you need to: HRV is one of the most reliable ways to measure your nervous system recovery.
One of the biggest problems people deal with is an excess of stress, which can lead to overwhelm and chronic disease. Athletes often train in order to better manage their stress, but we chronically over-train, and many end up pushing themselves closer to disease rather than away from it. For more information on overtraining, check out my article here.
HRV measurements can help you measure your body’s stress level, and predict how you should train, eat, sleep, and spend your time on a given day. How? Well, first lets talk about what exactly HRV is.
What is Heart Rate Variability?
The sinal-atrial (SA) node is a collection of cells inside your heart which fires electrical signals which travel throughout your heart muscle and cause a contraction. Basically, the SA node triggers a heart-beat. Generally, your SA node will trigger a certain number of contractions per minute, or your hearts beats per minute (BPM.)
The space of time between two contractions compared to the space of time between them and the next contraction is your heart-rate variability. Basically, if the spaces between your contractions are varied in length, you have a high HRV score. If the spaces between contractions are even, you have a low HRV score.
How does this relate to recovery? Well, your SA node is influenced by your para-sympathetic and sympathetic nervous systems. Para-sympathetic is your resting nervous response, and sympathetic is your active, aka Fight-or-Flight response. Both of these systems work synergistically with your heart to maintain efficiency and appropriate heart function.
As you become overtrained, your nervous system becomes taxed and less capable of influencing your heart rate appropriately.
Endurance athletes find themselves in a primarily para-sympathetic state, for example. As endurance athletes over-train, their HRV gets lower, due to the fact that the para-sympathetic nervous system primarily operates with the heart by releasing acetylcholine that lowers HRV.
Power athletes on the other hand, will often display wide-ranging HRV scores from day to day, due to over-activation of the sympathetic nervous system, which raises HRV by releasing epinephrine and norepinephrine (also known as adrenaline and noradrenaline.)
Therefore there are two scenarios which can indicate overtraining:
Low HRV scores, often associated with para-sympathetic imbalance from overtraining in endurance sports
Highly variable HRV scores, often associated with overtraining in power sports like crossfit.
But how do we measure this? How can we actually use HRV ourselves?
Measuring and Using Heart-Rate Variability
You don’t need fancy gear to measure HRV. All you need is a chest-strap heart rate monitor, and a smart phone. There are many fancy devices on the market, and some of them are great self-quantification tools, but when it comes to bang-for-your-buck, just grab a heart rate monitor.
Not all heart-rate monitors will work, you need one that is bluetooth capable. I recommend the Polar H7, located on amazon here.
Once you have the monitor, you’ll need an app that can use it to measure HRV. Personally, I use Ben Greenfield’s App Naturebeat but you can also use something like Sweetbeat, developed by Sweetwater Health, which is also just a great resource for learning more about HRV.
For an in-depth run through on how to use these apps and what kinds of deep data you can attain, check out this interview.
For the basics, now that you have the monitor and the app, start measuring your HRV daily.
Your goal is to be able to compare your day-to-day HRV scores, so consistency is key. To do this properly, measure your HRV as soon as you wake up, before doing anything else for the day. Don’t get up and shower, don’t meditate or do a quick workout, just put on your monitor while you’re laying in bed, and do a 5 minute HRV reading.
Many factors can influence HRV, and this is why you should measure it before you get going for the day.
Once you have a reading, here are the key take-aways:
HRV that varies greatly from day to day means your sympathetic nervous system may be imbalanced. Refrain from doing high-intensity power workouts for a few days.
Low HRV scores on a consistent basis may mean your para-sympathetic nervous system is imbalanced. Avoid chronic cardio for a few days.
For a fully optimized nervous system, your HRV should be above 90. If you have numbers above 90, you’re already in a good place and you should determine whether to train or not by whether your HRV is above 90. If you dip below, then you should consider taking a recovery day. Again though, if your HRV is varying a lot from day to day, even if it is above 90, then you may have sympathetic imbalance. Just keep an eye out.
If you determine that your HRV is off and you need to recover, stick with light, easy workouts such as Tai Chi, basic yoga, walking your dog, etc. Meditation has also been shown to raise HRV.
If you want to do more advanced self quantification, like measuring your hrv all-night long to determine your sleep quality, you may be interested in checking out a more advanced device. The OURA ring has become part-and-parcel to the training of the most elite athletes and coaches. It can be a game-changer for sleep optimization, which is considered by many to be the most important aspect of staying healthy. For my full article on sleep, check this out.
Next, there is an awesome little bit of technology that actually trains you to have better HRV scores. This device is called the Emwave2, by the heartmath institute. The institute is one of the leading researchers on HRV, and they use their products to address mental and physical health be training you to control your HRV through meditation-like exercises.
The Emwave is a device you can use on the go, or you can use it with a comprehensive computer program that measures your HRV and gives extensive feedback. I love it, however, if you’d be more interested in a phone-based device, they have another called the inner balance, which works with a phone-based app. Each device has different advantages and disadvantages when it comes to convenience and data recording, but they both do essentially the same thing. The Emwave offers more in depth data when paired with the computer program, but the inner balance keeps its data right there on your phone.
For a list of research studies on HRV, you can visit the heartmath institutes research library here.
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