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What, Why & How of HRV

With the increased popularity of devices such as the Whoop and Oura Ring the interest in HRV has soared. A number of athletes now are aware of their HRV number and like any piece of data they want to try and maximize their score. But has anyone told them how to improve it?

In this article I want to discuss what HRV is and how to have a proactive positive effect on it. Yes, anyone who has been tracking it knows that more sleep and less alcohol have a direct effect but what else? How can you have a purposeful affect on it throughout the day to help it improve over time. 

What is HRV?

HRV stands for Heart Rate Variability; which is a measure of the time in-between your heart beats.  Most people are aware of their resting heart rate; the number of times your heart beats in a minute. What most people are unaware of is that the heart does not beat at an evenly paced manner. So if you have a resting heart rate of 60 beats per minute that does not mean your heart is beating once every second.

As you inhale your heart rate increases (speeds up) and as you exhale your heart rate decreases (slows down). You can give this a try.  Find your pulse in your neck or wrist, now take a long breath through your nose paying attention to your pulse; then allow a long slow exhale through your nose. Did you notice that as you began inhaling the beats got closer together (increased HR) and then  as you exhaled the space between your heart beats got bigger (slowed down)? That is HRV; that variability between the spacing between the beats you felt during those inhales and exhales. 

Why is HRV important?

HRV is giving us an insight into how your autonomic nervous system (ANS) is functioning. your ANS has two sides: your ‘fight or flight’ response (sympathetic nervous system) and your ‘rest and relaxation’ response (parasympathetic system). 

Think about how your heart rate responds when you are in the ‘fight or flight’ response? That’s right, you get excited and your heart starts pounding; the spacing in-between beats is short. How about during the 'rest and relaxation’, your heart rate slows down increasing the time between beats. Also think about how your breathing is affected by those stages as well. During the ‘fight or flight’ your breathing typically becomes shallow and rapid where the opposite happens when you are in the rest and relaxation phase while taking slower deeper breaths. 

Why does having a few beers before bed have a negative affect on your HRV? It is because your body is not actually in a state of rest after a few drinks at night while sleeping. The alcohol has introduced a level of stress that the body is dealing with causing it to spend more time in the ‘fight or flight’ response rather than the typical ‘rest and relaxation’ that you would be in during a good night's sleep. The body has to process the alcohol throughout the night which is causing your HR as well as your reperitory rate to stay more elvelated; similar to what it is throughout the day while at work or training. This means that since there is little change in your state of stress which leads less variabilty between those heart beats resulting in waking up to a lower HRV score. 

So a higher HRV score is letting you know that you're spending time in both sympathetic and parasympathetic states throughout the day. Spending time in both states provides us with the tight spacing between heart beats during the ‘fight or flight’ as well as the larger spacing between beats that happens during the ‘rest and relax’ response.  A properly functioning autonomic nervous system is one that can move easily between the two states of being excited and relaxed.  To have a better functioning ANS you need to be in both states throughout the day; you need to be excited at times and you also need to be able to be relaxed. Living a life steadily in either of those states is not ideal. If your score is going up over time that means your body is doing a better job moving from one state of stress to the other throughout the day.

As mentioned above, your breathing also distinctly responds to those phases of stress as well. your breathing will respond by increasing your respiratory rate when stressed and then decreasing that rate as you relax. This is the key understanding to how you can proactively affect your HRV.  

Breathing can be controlled; so if you understand how your breathing is affected by your autonomic nervous system then you can affect your ANS with your breathing; it is a two way street. 

How to proactively affect HRV?

The nervous system is a system of communication in your body to allow the brain to understand what the body is doing or needs and for the body to know what the brain wants. The vagus nerve mostly sends information from the body back to the brain. There are also efferent vagus fibers which sends messges from the brain to places like the heart. So the resulting two-way flow of information from the brain impacts the physical system (body) and the physical system impacts the brain. 

This means that your brain can impact your respiratory rate as well as your respiratory rate can impact your brain.  We have all experienced this in the past in both ways.  Remember a time when you might have just been sitting at your desk and started thinking about a work deadline, or an upcoming race and all of a sudden your heart rate increases and you start breathing a bit heavier. Well that is your brain affecting your physical body.  Or another part of the day when your brain is thinking about a thousand things at once; you might just take a deep breath in and out; slowing down your breathing and bringing a sense of calm to your mind.  That is your physical system impacting your brain.  

So if you understand how your breathing can affect your brain (i.e nervous system) then you can have a direct proactive effect on your autonomic nervous system by using breathing exercises to upregulate to activate your sympathetic nervous system (ie. get psyched up) or exercises that downregulate to activate the parasympathetic nervous system (ie. calm down).  

As mentioned before, an improvement in your HRV is a sign that your body is shifting more effciently between the two autonomic nervous systems (sympathetic and parasympathetic). How does your body get better at doing something? Well, simply by practicing it.  You can practice this by doing different breathing exercises throughout the day; giving your body/brain the opportunity to migrate from states of excitement to relaxation as well as from relaxation to excitement.  This is what creates that variability you are so intently tracking.  

Remember living in a constant state of stress means your sympathetic nervous system is constantly active which will result in a lower HRV. The flip side of that is also true; if you are living in a state of constant relaxation your parasympathetic nervous system is constantly active which is also not ideal.  If you move between the two systems more throughout the day then it will result in a higher HRV meaning you have a better functioning autonomic nervous system that can easily move from ‘fight or flight’ to ‘rest and relax’ seamlessly throughout the day as your body requires it to handle the current situation. A good functioning nervouse sytems is one that allows you to calm down when you are stressed but also one that can get you pumped up and excited when you need to act.     

What is a good HRV score?

Hard to say because everyone is different. The key is to know what is your baseline HRV is on a day to day basis.  To find your baseline track it for a week and see what the average number is for those seven days; that is your baseline. Again this is not a sign of how physically fit you are; it is a representation of how well your nervous system is working.  After your baseline is set you can use that as your gauge. If you see a drop in your HRV score of 20% from the day before you might want to keep the workout on the lighter side; it seems that the body might already be dealing with some underlying stress (physical, mental, emotional, etc..). If the number is 40% less than your typical baseline you should probably take the day off from training.   


If you are going to take the time and mental energy to track something then you better understand how to impact that number. What is the point of tracking data if you don’t know how to affect it?  Just sitting back and hoping the number improves is not a good solution to training. You need to have a plan and then do the work necessary to get the results you want. A breathwork practice is the ground work to take control of your HRV on a daily basis. I do offer breathwork programs that will help you maximize your results. if you are interested in learning more you are welcome to sign up for a free consultation.

Keep moving forward.

Brian Hammond


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