It’s no surprise or secret that the state of our heart directly reflects our overall health. However, more specifically its rhythm (heart rate) has been linked to life expectancy. The heart rate is how many times your heart beats per minute, this varies a lot during the day, it’s at its lowest during sleep and the highest when exercising. Our health is judged on the resting heart rate (RHR) which is the average heart rate while you are awake and in restful state, but not asleep. Normal adult range is between 60 to 100 beats per minute (bpm).
Resting Heart Rate
RHR varies from person to person, and there’s many factors directly influencing it, like fitness level, stress, age, weight and even medications. Athletes, like runners and cyclists tend to have much lower RHR, at 40-60 bpm. A slower beating heart could be seen as a more efficient one, as it can distribute the blood throughout the body with less beats, so in turn there is less “wear and tear” on the heart, and thus potentially leading to a longer, healthier life. Now, that being said our body is a complex system, so having a low RHR does not directly mean you’re healthy, there’s many components to it and many parameters that are linked to longevity. Sadly, we can’t pick one and only optimise that hoping it cancels out other ‘worse performing’ areas.
Heart Beat Hypothesis
A lot of studies have looked at various animals’ HR and how it compares to their life expectancy, and there’s a clear inverse relationship. However, humans' don’t really much that trend line, we have a higher life expectancy compared to those with similar HRs.
Relative Risk of Disease
Even though the normal RHR is from 60 to 100 bpm, that is quite a big range. A study by Boudalas et al., reported how relative risk varied at different ranges of RHR (see fig below).1 The LHS shows the results of a 23-yr follow-up of 5,713 asymptomatic men without any heart disease; they reported the relative risk of death from any cause, sudden and non-sudden death from myocardial infarction (heart attack) of healthy men.2 A RHR > 75 had the highest relative risks for all three categories.
The RHS shows the all-cause mortality of a Copenhagen Male Study of 2,978 healthy men without heart disease or diabetes. The risk had been adjusted for age, BMI, physical activity, fitness, maximal myocardial oxygen consumption (MVO2 max), leisure time, tobacco consumption, alcohol intake, systolic / diastolic pressure, serum cholesterol and triglycerides.3 Similar results were shown for this study as well.
The study looked at many other risks, like that of cardiovascular disease. Overall, the conclusion is that a higher fast heart rate itself affects the cardiovascular system in many ways and hence why it may affect survival. From a physiopathology standpoint what occurs due to a faster RHR is increased ventricular work, myocardial oxygen consumption, endothelial stress, aortic/arterial stiffness, decreases myocardial oxygen supply, and many more.
Reducing RHR
The good thing is that RHR can be altered by lifestyle modifications - like most things in fairness. Regular aerobic exercise / cardio, removing stimulants like caffeine, drugs, alcohol, tobacco, having a normal body weight. And of course two of most important aspects for most things health-related: low stress and good quality & quantity of sleep.
A drug that is often prescribed to cardiac patients or those with hypertension (high blood pressure) is beta-blockers. The way they work is by blocking the effects of a hormone called epinephrine (aka adrenaline). This causes the heart to beat more slowly and with less force, and hence this lowers blood pressure. They also help widen veins and arteries to improve blood flow. You can see why this is beneficial in someone with a weakened heart as not as much pressure and stress is put on the heart to pump blood around the body.
A review reported decreased risk of death in patients with heart disease on beta blockers.4 On a side note, they also reported that genome-wide association studies using Mendelian randomisation showed a causal relationship RHR and longevity.
Another study outlined that beta-blocker outcomes studies observed a relationship between the reduction in RHR and mortality (see figure below).5 Bit of a fun fact is that most beta-blocker names end -lol (often -olol and sometimes -alol too).
The power of Wearables
There’s a huge boom in wearable technologies to monitor health, from the Apple Watches to the WHOOPs and FitBits. They show a live feed of many different variables like current heart rate, RHR, oxygen levels, steps and many many more. There’s been a bit of controversy as to whether these are actually accurate, and many people are obsessing over the values shown on their wrist. A 2019 study looked at the accuracy of the Apple Watch 3 and the Fitbit Charge 2 by comparing them to ECGs (the gold standard); both watches provided acceptable heart rate accuracy (<±10%) for almost all activities. 6 Another new study led by UCL, showed that smart watches could be used to detect a higher risk of developing heart failure and irregular heart rhythms. 7 They looked at ECGs produced from consumer wearable devices and concluded it may help with detecting and preventing future heart disease.
To sum up, your RHR could truly be an indication to your overall health and lifespan, and lowering the rhythm of your heart simply is beneficial for many aspects. Although I’m not an advocate for micro-monitoring every single measurement and value (in certain aspects that is…), maybe getting a smart watch could prove more useful that not in ensuring that your vitals are on the good side of the normal range.
As usual, I’ve added some links below. I hope you enjoyed - see you next week! :)
Boudoulas, K.D., Borer, J.S. and Boudoulas, H. (2015). Heart Rate, Life Expectancy and the Cardiovascular System: Therapeutic Considerations. Cardiology, [online] 132(4), pp.199–212. doi: https://doi.org/10.1159/000435947
Jouven X, Empana JP, Schwartz PJ, Desmos M, Courbon D, Ducimeltiere P: Heart rate profile during exercise as a predictor of sudden death. N Engl J Med 2005;152:1915-1958 [PubMed] https://doi.org/10.1056/NEJMoa043012
Jesen MT, Suadicani O, Hein HO, Gynderlberg F: Elevated resting heart rate, physical fitness and all-cause mortality: a 16-year follow-up in the Copenhagen Male Study. Heart 2013;99:882-887. [PubMed] https://doi.org/10.1136/heartjnl-2012-303375
Jensen, Magnus T. “Resting heart rate and relation to disease and longevity: past, present and future.” Scandinavian journal of clinical and laboratory investigation vol. 79,1-2 (2019): 108-116. doi: https://doi.org/10.1080/00365513.2019.1566567
Karl Swedberg, Pure heart rate reduction: further perspectives in heart failure, European Heart Journal Supplements, Volume 9, Issue suppl_F, September 2007, Pages F20–F24, https://doi.org/10.1093/eurheartj/sum031
Nelson BW, Allen NB. Accuracy of Consumer Wearable Heart Rate Measurement During an Ecologically Valid 24-Hour Period: Intraindividual Validation Study. JMIR Mhealth Uhealth. 2019;7(3):e10828. Published 2019 Mar 11. doi: https://doi.org/10.2196/10828
Michele Orini, Stefan van Duijvenboden, William J Young, Julia Ramírez, Aled R Jones, Andrew Tinker, Patricia B Munroe, Pier D Lambiase, Premature atrial and ventricular contractions detected on wearable-format electrocardiograms and prediction of cardiovascular events, European Heart Journal - Digital Health, Volume 4, Issue 2, March 2023, Pages 112–118, https://doi.org/10.1093/ehjdh/ztad007
A breath specialist helped me solve my chronic hyperventilation by teaching me how to re-train my system to need less air and have longer inhales and exhales. How about using this type of breathwork (in conjunction with what you mentioned) to train a lower RHR?