Medical Compass: Understanding resting heart rate

Medical Compass: Understanding resting heart rate

Studies have shown that combined strength and endurance training may lower RHR in women. METRO photo
Certain types of exercise may lower RHR

By David Dunaief, M.D.

Dr. David Dunaief

How many of us regularly check our resting heart rate, or pulse, and what can we learn from it?

Resting heart rate is pretty important. In fact, it may play a role in longevity, heart disease — including heart failure, arrhythmias, heart attacks and sudden cardiac death — and even chronic kidney disease.

A “normal” resting heart rate is between 60 to 100 beats per minute (bpm). If your resting heart rate (RHR) is above 100 bpm, this is referred to as tachycardia, or a racing heartbeat, and it has potentially serious consequences. However, even normal RHRs can be stratified to identify risks for diseases. What I mean is that, even in the normal range, as your RHR increases, so do your potential risks. Actually, resting heart rate below approximately 70 bpm may be ideal.

The good news is that RHR is modifiable. Methods that may reduce your rate include medications, such as beta blockers, and lifestyle modifications, including meditation, dietary changes and exercise.

Impact on life span

Reducing RHR may be an important component in living a longer, healthier lifestyle. In the Copenhagen Male Study, a prospective study that followed 2,798 participants for 16 years, results showed that those with higher resting heart rates had a greater risk of death (1). There was a linear relationship between the risk of death and increasing RHR. Those who had a resting heart rate above 90 bpm were at a threefold greater risk of death, compared to those who had a RHR at or below 50 bpm. RHR was inversely related to the amount of physical activity.

Thus, the authors concluded that a “healthy” person with higher RHR may still have a shorter life span, with all other factors being equal, such as physical activity and blood pressure.

Predictor of Hypertension?

An analysis of 4,000 young adult participants in the 30-year CARDIA cohort study found that a 10 bpm higher RHR had a significant impact on future hypertension, or high blood pressure, experienced in middle age (2). This association was found with a 10 bpm increase in RHR among black and white men and white women. Interestingly, black women did not show the same association. The study authors hypothesize that this may suggest racial differences in sympathetic nervous activity impacts on hypertension among women. Of course, additional research will be necessary to delve deeper into this.

Heart disease mortality

In the Nord-Trondelag Health Study, a prospective observational study, those who had a higher RHR at the end of the study than they did at the beginning of the study 10 years prior were more likely to die from heart disease (3). In other words, as the RHR increased from less than 70 bpm to over 85 bpm, there was a 90 percent greater risk of heart disease, compared to those who maintained a RHR of less than 70 throughout the two measurements. This study involved 30,000 participants who were healthy volunteers at least 20 years old.

Heart attacks

In the Women’s Health Initiative, results showed a 26 percent decrease in the risk of cardiovascular events in those postmenopausal women who had a RHR below 62 bpm, compared to those who had a RHR above 76 bpm (4). Interestingly, these results were even more substantial in the subgroup of women who were newly postmenopausal, ranging in age from 50 to 64.

Effect on kidney function

I have written many times about chronic kidney disease. An interesting follow-up is resting heart rate and its impact on kidney function. In the Atherosclerosis Risk in Communities Study, results showed that the most severe form of chronic kidney disease, end-stage renal disease, was 98 percent more likely to occur in those with the highest RHR, compared to those with the lowest (5). There were approximately 13,000 participants in the study, with a 16-year follow-up.

The authors hypothesized that this negative effect on the kidney may be due to a loss of homeostasis in the autonomic (involuntary) nervous system, resulting in blood vessel dysfunction, such as increased inflammation and vasoconstriction (narrowing).

Lowering RHR

Studies have shown that combined strength and endurance training may lower RHR in women. METRO photo

A meta-analysis of controlled studies analyzed the effects of different types of exercise on RHR (6). Studies’ interventions included a range of exercises, such as high intensity interval training, including ball and team sports; endurance or strength training; yoga; qigong; and tai chi. Some studies’ participants were limited to one gender.

No surprise, analysis found that all interventions lowered RHR compared to control groups that did not exercise. The greatest results in lowering RHR were in endurance training, yoga, strength training (females only), and combined endurance and strength training (females only).

Can RHR be too low?

Is there a resting heart rate that is too low? Well, it depends on the context. If you are a marathoner or an athlete, then a RHR in the 40s may not be abnormal. For a healthy, physically active individual, it is not uncommon to have a resting heart rate in the 50s. However, if you are on medications that reduce your RHR and/or have a chronic disease, such as heart failure, it is probably not advisable to go much below 60 bpm.

Always ask your doctor about the appropriate resting heart rate for your particular situation.

Thus, resting heart rate is an easy and inexpensive biomarker to potentially determine risk stratification for disease and to increase longevity, even for those in the normal range. By monitoring and modifying RHR, we can use it as a tool for primary disease prevention.

References:

(1) Heart Journal 2013 Jun;99(12):882-887. (2) Hypertension. 2020 Sep;76(3):692-698. Epub 2020 Aug 12. (3) JAMA 2011; 306:2579-2587. (4) BMJ. 2009 Feb 3;338:b219. (5) J Am Soc Nephrol. 2010 Sept;21(9):1560-1570. (6) J Clin Med. 2018 Dec; 7(12): 503.

Dr. David Dunaief is a speaker, author and local lifestyle medicine physician focusing on the integration of medicine, nutrition, fitness and stress management. For further information, visit www.medicalcompassmd.com.

SIMILAR ARTICLES

NO COMMENTS

Leave a Reply