Heart Rate Recovery: The Key to Saving your Life?

https://www.istockphoto.com/vector/very-strong-heart-gm905167764-249591819

Cardiovascular diseases (CVDs) are the number one cause of death across the globe (roughly 18 million people a year). We can consider any disorder of the heart, blood vessels, coronary heart disease, cerebrovascular disease, and rheumatic heart disease (amongst others) as some of the diseases that fall under this umbrella (Kakkar & Lee, 2007).

I have spent a lot of my efforts at NIH to try and understand CVDs a little bit better, and in fact, we may be using cardiometabolic parameters in a future study! Although medicine is typically a reactionary field (an individual has a heart attack and is raced to the emergency room to fight for his life), I have seen a paradigm shift at NIH to focus on preventive medicine. In essence, this would be stopping the progression of the disease before it requires intensive medical attention. To do this, we of course need proper diagnostic tests.

What if there was one test you could perform at the gym, outside in your neighborhood, or even at your next primary check-up that could help predict how susceptible you are to developing CVDs in the future?

This is precisely what I have begun to dig into over the last several weeks in some of my free time.

This has brought me to the concept of Heart Rate Recovery (HRR).

HRR is defined as “the decrease of heart rate at 1 minute after cessation of exercise” and is an imperative predictor of all‐cause mortality and death associated with coronary artery disease (van de Vegte et al., 2018). The concept is quite simple. Following the completion of your exercise routine, you immediately take your heart rate. Then one minute later, you check your heart rate again. The difference between those two values is known as your HRR. I will describe a practical way to use this below.

We have data that demonstrates that HRR is a verified predictor of coronary artery disease (Lipinski et al., 2004; Morshedi-Meibodi et al., 2002), death from coronary artery disease (Jouven et al., 2005) and cardiovascular (Myers et al., 2007) non-cardiovascular (Jouven et al., 2011) all‐cause mortality (Cole et al., 1999, 2000; Jouven et al., 2005; Morshedi-Meibodi et al., 2002).

In sum, there is a negative correlation between HRR and risk for CVDs (As HRR increases your risk for CVDs decreases and vice versa).

Now this wouldn’t be a Plotkin article if I didn’t throw some biochemistry at you.

HRR is at the interplay between our parasympathetic (rest and digest) and sympathetic (fight or flight) nervous systems (these are part of our autonomic nervous system). In a simple sense, when we exercise, we shift our body into the sympathetic state. This sends a signal to your heart to increase the amount it beats per minute to ultimately shuttle more oxygen-rich blood throughout your body to fuel your skeletal muscles. On the contrary, as your body transitions into the resting-state, your parasympathetic nervous system takes over, thereby sending a signal to your heart to slow down.

So, your HRR is essentially how fast your autonomic nervous system can react to stress (or lack thereof). If this happens quickly (a fast decrease in your heart rate following cessation of exercise) it indicates a robust nervous system, and a conditioned body capable of responding rapidly to its environment (Imai et al., 1994).

We do have some literature values on what is considered a good HRR score, but as per any physiological parameter, we are going to see a lot of day-to-day variation based on sleep, stress, nutrition, etc…(Allen & Breslow, 2017)

A study of 2,500 adults over a six-year period demonstrated that the median HRR is about 17 beats/min, with a range from the 25th to 75th quartile being 12 to 23 beats/min. However, the average age of participants in this study was 57 (Cole et al., 2000) and we know that HRR decreases past the age of 60 (N. et al., 2018).

Another study of 274 elite male athletes demonstrated that those above the age of 18 had an average one minute HRR of 29.5 beats and those under the age of 18 had an average one minute HRR of 22.4 beats (Suzic Lazic et al., 2017).

Therefore, from these data we can conclude that a HRR between 20–30 is a good score to shoot for if you are young to middle-aged, and then this can potentially dip down to 15 beats/minutes and still be considered a solid score as you get into the 50+ age category.

But we can make this data more meaningful by taking weekly or biweekly (or more if you want) HRR scores of ourselves, rather than worrying about whether our scores match the literature values.

To do this practically, it would be best if you had some sort of heart rate monitor (watch, polar heart strap, or even the monitors on your gym equipment). But you could use the old school method of taking your pulse.

Ideally, you want to test your HRR after spiking your heart rate…so a leisurely walk may not be your best bet for this one. Although I have a Polar heart rate strap that I use on all my bike rides, I also use the “Talk test.” Simply engage in some sort of exercise where you are no longer able to hold a constant conversation. Keep that pace for the length of your workout and immediately upon completion check your heart rate monitor (or see my image below for how to take your pulse). Then wait a minute and check again.

Obviously not ideal…but it could work if you have no other options. https://www.heartrhythmalliance.org/stars/ca/know-your-pulse

Now I know what you are thinking: “But Adam, these heart rate monitors are highly inaccurate, aren’t they?” And you are absolutely correct, I trust my Polar heart rate as that is the gold standard, but I do not trust any other monitor. But, accuracy in this case does not matter. Instead, we care about precision.

Most people do not even realize there is a difference in these two concepts. Accuracy refers to how close a measurement is to the true or accepted value, whereas precision refers to how close measurements of the same item are to each other. And yes, you can be precise without being accurate. For instance, imagine you are shooting an arrow at a target. An accurate strike would be hitting the bullseye. Let’s say I hit the outer skirts of the target (an inaccurate strike). But I try again with a second arrow and hit the exact same spot on the target. I am inaccurate, but highly precise.

We just need the data to be precise because all we care about is the change (the delta) between our heart rate right at exercise completion, and heart rate 1 minute later. So, it doesn’t matter if my heart rate monitor reads a heart rate that is 10 beats too fast every reading, as long as it does it every single time…so I can get precise readings to track consistently.

Thus, once we have about a month’s worth of data, we can start to see whether our average HRR is increasing or decreasing. As mentioned above, a decreasing HRR is probably a bad sign in terms of overall fitness and risk for CVD, whereas an increase in HRR is the exact opposite, and it means you are doing something right. Now of course, do not freak out about a few beats or two, just keep an eye on this. This is simply one diagnostic tool out of many. But it is a tool that you can constantly keep an eye on, and if you see a downward trend, it may be worthwhile to go see a medical doctor to see if it is a sign of an underlying problem.

I will say quickly that we do have newer data that a 10 second HRR test is actually a superior predictor of outcome compared with HRR at later time intervals (such as 1 minute; van de Vegte et al., 2018). However, because this is a more recent finding, we do not have a ton of literature on ideal values, so that is why I chose to focus on the 1-minute HRR test. But, if you want to try out the HRR test at 10 seconds post exercise, as opposed to 1-minute post exercise, that is certainly acceptable. As long as you keep it consistent 😉

I hope you all can start implementing this into your weekly routine. Not to be dramatic, but this one number could be something that potentially saves your life one day.

Allen, C., & Breslow, E. (2017). Case Study // the Science and Application of Heart Rate Recovery.

Cole, C. R., Blackstone, E. H., Pashkow, F. J., Snader, C. E., & Lauer, M. S. (1999). Heart-Rate Recovery Immediately after Exercise as a Predictor of Mortality. In New England Journal of Medicine (Vol. 341, Issue 18, pp. 1351–1357). https://doi.org/10.1056/nejm199910283411804

Cole, C. R., Foody, J. A. M., Blackstone, E. H., & Lauer, M. S. (2000). Heart rate recovery after submaximal exercise testing as a predictor of mortality in a cardiovascularly healthy cohort. In Annals of Internal Medicine (Vol. 132, Issue 7, pp. 552–555). https://doi.org/10.7326/0003-4819-132-7-200004040-00007

Imai, K., Sato, H., Hori, M., Kusuoka, H., Ozaki, H., Yokoyama, H., Takeda, H., Inoue, M., & Kamada, T. (1994). Vagally mediated heart rate recovery after exercise is accelerated in athletes but blunted in patients with chronic heart failure. In Journal of the American College of Cardiology (Vol. 24, Issue 6, pp. 1529–1535). https://doi.org/10.1016/0735-1097(94)90150-3

Jouven, X., Empana, J.-P., Schwartz, P. J., Desnos, M., Courbon, D., & Ducimetière, P. (2005). Heart-Rate Profile during Exercise as a Predictor of Sudden Death. In New England Journal of Medicine (Vol. 352, Issue 19, pp. 1951–1958). https://doi.org/10.1056/nejmoa043012

Jouven, X., Escolano, S., Celermajer, D., Empana, J. P., Bingham, A., Hermine, O., Desnos, M., Perier, M. C., Marijon, E., & Ducimetière, P. (2011). Heart rate and risk of cancer death in healthy men. In PLoS ONE (Vol. 6, Issue 8). https://doi.org/10.1371/journal.pone.0021310

Kakkar, R., & Lee, R. T. (2007). Cardiovascular diseases. In Drug Discovery Today: Disease Models (Vol. 4, Issue 4, pp. 163–164). https://doi.org/10.1016/j.ddmod.2008.04.001

Lipinski, M. J., Vetrovec, G. W., & Froelicher, V. F. (2004). Importance of the first two minutes of heart rate recovery after exercise treadmill testing in predicting mortality and the presence of coronary artery disease in men. In American Journal of Cardiology (Vol. 93, Issue 4, pp. 445–449). https://doi.org/10.1016/j.amjcard.2003.10.039

Morshedi-Meibodi, A., Larson, M. G., Levy, D., O’Donnell, C. J., & Vasan, R. S. (2002). Heart rate recovery after treadmill exercise testing and risk of cardiovascular disease events (The Framingham Heart Study). In American Journal of Cardiology (Vol. 90, Issue 8, pp. 848–852). https://doi.org/10.1016/S0002-9149(02)02706-6

Myers, J., Tan, S. Y., Abella, J., Aleti, V., & Froelicher, V. F. (2007). Comparison of the chronotropic response to exercise and heart rate recovery in predicting cardiovascular mortality. In European Journal of Preventive Cardiology (Vol. 14, Issue 2, pp. 215–221). https://doi.org/10.1097/HJR.0b013e328088cb92

N., S., T., S., K.A., G. C., N., H., S., F., J.G., M., B., M., F., L.-J., & T.G., A. (2018). Prognostic performance of heart rate recovery on an exercise test in a primary prevention population. In Journal of the American Heart Association (Vol. 7, Issue 7). http://www.embase.com/search/results?subaction=viewrecord&from=export&id=L621547562%0Ahttp://dx.doi.org/10.1161/JAHA.117.008143

Suzic Lazic, J., Dekleva, M., Soldatovic, I., Leischik, R., Suzic, S., Radovanovic, D., Djuric, B., Nesic, D., Lazic, M., & Mazic, S. (2017). Heart rate recovery in elite athletes: the impact of age and exercise capacity. In Clinical Physiology and Functional Imaging (Vol. 37, Issue 2, pp. 117–123). https://doi.org/10.1111/cpf.12271

van de Vegte, Y. J., van der Harst, P., & Verweij, N. (2018). Heart rate recovery 10 seconds after cessation of exercise predicts death. In Journal of the American Heart Association (Vol. 7, Issue 8). https://doi.org/10.1161/JAHA.117.008341

Post-Baccalaureate research assistant in the Molecular and Clinical Nutrition Lab at the National Institutes of Health