THE ABC’s OF HRV
I’m a bit of a nerd when it comes to health and well-being…Particularly when it comes to myself and understanding my own body! Lately I have been experimenting with a new type of health monitoring technology, known as heart rate variability.
Heart rate variability allows me to look at my heart rate in a different way. A regular heart rate monitor may tell you your heart rate, i.e. how many times your heart beats in one minute. A heart rate of 60 beats per minute is approximately 1 beat every second. Heart rate variability takes a closer look, not only at how often the heart is beating, but also at the variability between each of the heart beats. For example, within that heart rate of 60 beats per minute, there may be some slight variation in the the time interval between subsequent heart beats. It may beat at 1.11 seconds apart sometimes, and 0.89 seconds at other times, or any other combination of time intervals, and yet still achieve a final heart rate recording of 60 beats per minute. Rather than looking at how fast the heart is beating, heart rate variability looks at the extent of variation that exists within these beat to beat time intervals. Make sense?
By looking at the variability between heart beats, we can glean new, objective information about our body, in particular about the state of our autonomic nervous system (click here to see my past blog post on the ANS and how we can ‘hack it’ through our breathing). The autonomic nervous system is the system responsible for controlling our bodies response to stress and recovery - in particular, whether we are in a state of ‘fight or flight’, or ‘rest and digest’, or somewhere in between. Through algorithms which interpret our heart rate variability data (I use the ‘Elite HRV’ app), we can be provided with a number which indicates where we are on the spectrum between the two states.
The HRV score is constantly changing throughout the day, depending on our circadian rhythm, whether we have been exercising / moving, sitting down / sleeping, eating food, under stress, or cognitively stimulated. Even emotional and social stimuli can have an influence! By taking an HRV recording every day (ideally within the first half hour of waking up, before the variables above have a chance to influence the score), overtime we can establish a baseline HRV score. Subsequent measurements can then show us where we are on that particular day, relative to our ‘regular’ HRV, in terms of autonomic control. Scores can range between 0 - 100, averaging around 60, but varying depending on the variables such as our age, gender, health, resilience to stress, and fitness level. For normative data provided by Elite HRV, see https://elitehrv.com/normal-heart-rate-variability-age-gender .
This metric is neat as it provides an objective method of determining your bodies readiness for exertion, in other words, the extent to which you have capacity to push your body (physically, cognitively, emotionally), or whether you would be advised to take an easy day instead. Obviously this metric is highly valuable in the scope of athletic training (determining when to maximize your ‘good’ days, and be gentler on your body when it needs a rest), and helping to prevent injuries or over-training. It can also be used in a clinical sense, within the scope of fatigue management programs for people suffering from chronic fatigue or cancer related fatigue (stay tuned for blog post number 2 on HRV for fatigue management).
I have been measuring my HRV levels via the use of a specific heart rate monitor (the Polar H10) that has a high enough recording frequency to detect these subtle differences in beat to beat variability. The data is interpreted and processed using the ‘Elite HRV’ app. What is interesting is that higher variability between heart rate intervals is actually a good thing and indicates having good parasympathetic control, or in other words, better ability for the body to switch over into ‘recovery mode’ as opposed to ‘stress mode’. (Note that we also need to have the neural drive to kick into gear when we need it! It’s all about balance and the ability to transition between the two states as needed). I really enjoy having this data as it provides me with an objective indicator of my capacity to push forward or pull back with my exercise training. This helps me to make decisions regarding whether I have capacity for a high intensity interval training work out, or whether I should switch to a stretching session and early night instead. It can also provide an early warning signal for any potential increases in fatigue due to illness or inflammation, as well as showing you the impact that other lifestyle variables, such as diet, caffeine, alcohol, sleep, and stress management can have on your physiology. Scientific data telling me exactly how much my body can tolerate - it’s the health nerds dream!
I will leave you with this one question... If you knew exactly the impact that different lifestyle choices had on your health (both positive and negative), do you think it would influence the way that you went about your everyday life??