HRV – Listen to Your Body.
I am a big believer in recording and respecting your HRV reading. Here is why.
Heart Rate Variability (HRV) is a simple tool that you can effectively use to see that your training is in line with your body’s ability to recover. Train beyond your body’s ability to recover, and you are either going to get sick, injured or psychologically overwhelmed.
What is HRV?
We all know what Heart Rate (HR) is. Put your finger on the pulse point on your wrist and count for one minute and you will get your heart rate per minute. Your sport watch will also have this capability. Lets say your HR is currently sitting at 60 beats per minute. It is beating once per second. HRV is concerned with the amount of time between beats. We essentially have 1000 milliseconds between each second. If your heart beats like a metronome with a gap of 1000 milliseconds you would have no variance or a low HRV. Let’s say your heart takes a 800 millisecond gap between one beat – slightly faster – and then a gap of 1200 milliseconds before the next beat – slightly slower- it will still be beating at a rate of 60 beats per minute but with a higher variance.
It turns out that a more metronomic beat is a sign that your body is taking strain and that a greater variance, one quicker beat followed by lets say, two slower beats etc. is a sign of better health, and for athletes, better adaptation to training load. Let’s unpack that a bit more.
Two nervous systems: Sympathetic Nervous System and Parasympathetic Nervous System.
Picture the scene. You are reading this blog while in the room next door a ‘friend’ is about to prank you. They are slowly blowing up a balloon, up to max pressure. The balloon is close to popping. They have managed to find a pin and have switched on their cell camera. They have taken their shoes off and are creeping up to you, socks quietly shuffling on the floor behind you…. got it? If you got immersed in the story, you would have felt a little jolt of adrenaline with a tension setting itself up somewhere in your gut. Your pulse rate would have increased, and you would have increased your respiration rate and started to breath more through the top section of your lung. This increase in sympathetic nervous system activity would have gotten you ready for an impending disaster, and with that your heart would have started to beat more steadily and thus your HRV would have dropped.
Now, lets put you into a different scene. You are in a totally safe place, it’s warm around you, there is a gently breeze blowing. You take a deep breath and feel totally calm. Your parasympathetic nervous system is enjoying the calm, and there are decent variances between the beats of your heart, causing your HRV reading to rise.
A little bit of anatomy coming up.
You have a really complicated nerve called the vagus nerve. It’s name has got nothing to do with Las Vegas, rather, the Latin origin means “wanderer”. That’s exactly what the nerve does. Most of the information flow from the nerve goes upward to the brain. This is primarily an afferent nerve, think of it as being like a newspaper reporter that sends information to head office, versus a boss who sends instructions down toward the workers. At the top of your lungs are a set of nerves that link up to the vagus nerve. When they get stimulated, they send information up that stimulates your sympathetic nervous system – remember that’s your stress nervous system that will bring about a fight, flight or freeze response.
At the base of your lungs are a set of nerves that also link up with the vagus nerve. When they are stimulated with deep breaths, they in turn stimulate your parasympathetic nervous system. That’s the zen part of you. Watch someone get some really bad news. One of their responses will be to sigh. As they sigh they breathe air deeply into their lungs and then slowly let that air out. They immediately feel more calm.
Let’s tie this up with a look at life and training.
The best way to live your life is to balance out times of stress with times of peace. Too much stress and you are going to get into psychological and/or physiological trouble. Too little stress and you will never accomplish anything. Times of stress will cause you to accomplish great things. They need to be followed however, by times of rest, where you recover. Times of stress will lower your HRV, times of rest will elevate your HRV.
Training is a form of stress. Those familiar with Training Peaks will know that Training Peaks assigns a stress score (TSS) to your training. The figure is a composite between your average heart rate during a workout and the amount of time spent on the workout. A low HR, 30 min run will have a low TSS (Training Stress Score). A hard run over two hours will register a high TSS.
Put too many hard workouts together with a stressful life style and your body will begin to break down. One of the first signs of this will be a decreased HRV. This becomes the primary reason to track your HRV on a daily basis. I encourage all the athletes that I coach to do so. My preferred app is the HRV4 app. You can find that on Google and download it to your smart phone. There is a small once-off cost. All I do is wake up in the morning and get my HRV read by the app. You place your finger over your cell phone’s light and camera. The light illuminates the small capillaries in your finger and the camera records them expanding and contracting as your heart beats. The app measures the gaps between beats over a minute and through a logarithmic function gives you a HRV readout. There is also a series of questions that you can choose to answer that tap into your psychological and physiological wellbeing. Too low a reading and the app will suggest that you back off a bit on your training intensity. I will take careful note of that and adapt the training that I have set out for myself for that day. I write my own programs versus a number of coaches that in turn get coached by other coaches. My thinking here is that if you can’t trust your own program why should you expect your athletes to trust the programs you write. I have a number of intense sessions every week. One or sometimes two hard swims, rides and runs. If I get a low HRV score, all I do is back off the intensity levels for that day.
Here is an example of my HRV a few weeks ago. I didn’t take it on one of the mornings.
I had a number of good days where I could train really well. I had two specific days in a row where it dipped and so I reduced my effort on the first day, and took it really easy on the second day. I am not sure why it dropped like that. We had gone through a bit of a stressful time and I might have been fighting off an infection. The reduction in both training time and intensity and a really good nights sleep ensured that my HRV went right back up and I was able to continue training normally without any further issues.
Things that will decrease your HRV score.
– Too many hard training sessions.
– A bad nights sleep.
– Alcohol. You can check that for yourself. There is a direct correlation be alcohol consumption and lowered HRV scores.
– Life stresses.
– Infection.
– Too many easily digestible carbs.
Things that increase HRV scores.
– Balancing hard and easy training sessions. This is one of the reasons that I work on a heart rate model when it comes to coaching.
– A good nights sleep.
– No alcohol later in the day. You are better off cutting most of it out.
– Balancing life stresses with times of rest. (Striving for a stress free life is both unrealistic and ironically, stressful).
– Learning how to deal with stress. This should include deep breathing exercises and keeping a journal where you take time to reflect on things that you are grateful for.
– Eating a diet that is balanced out correctly for your physiology.
Further reading:
Heart Rate Variability and Longevity – https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.114.009778 and https://pubmed.ncbi.nlm.nih.gov/33041862/
Heart Rate Variability and Diabetes –
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5880391/
Better recovery levels mean two things for an athlete.
1. Your last workout helped produce fitness.
2. You are ready to build on that fitness during your next workout.
As Steve Magness has pointed out, Stress + Rest = Growth. Read more here – https://sbrsport.co.za/2020/10/11/stress-rest-growth/
Regularly tracking your HRV will ensure that you are properly rested before going forward.
Hope this helps,
Mike Roscoe.
Kinesiologist and Coach.
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