Heart rate — the number of times the heart beats per minute — would seem to be an obvious variable in health and longevity, especially as it concerns heart disease. True to intuition, it turns out that resting heart rate is important for health.
Resting heart rate (RHR) can be compared to VO2max, in that they both measure a parameter that itself has many facets. RHR measures not just the integrity and health of the heart, but the overall health of the blood and the tissues it oxygenates, as well as the nervous and hormonal systems, which play important roles in setting heart rate.
A good deal of research has looked into the association between RHR and cardiovascular disease — which is the leading cause of death in the U.S. — and also the association with total death rates.
In all cases, the research has found that
Associations don’t get much easier than this for a test that you can do yourself at home, no expense or doctor’s order required.
Since there’s an abundance of research in this area, let’s just look at one recent study: “Elevated resting heart rate is an independent risk factor for cardiovascular disease in healthy men and women”.1
The study was done in Finland. The Finns take a keen interest in heart disease because their country had at one time the world’s highest rate of heart disease.
The subject population consisted of 10, 519 men and 11.334 women, more than enough to generate solid data. Follow-up time for any individual in the study ranged from 6 to 27 years from the time that RHR was measured. Median follow-up time was 12 years.
Subjects who had a previous heart attack, were being treated for high blood pressure, or had heart failure or angina (chest pain) were excluded, so the study was looking at people who showed no signs of heart disease.
When grouped into quintiles (fifths) of resting heart rate, the results for RHR vs cardiovascular mortality looked like this:
Keep in mind here that each quintile contains exactly 1/5 of the group, e.g. 1/5 of all men and women had a resting heart rate >82, and only 1/5 had one of <60.
Men in the highest quintile had nearly four times the rate of death from cardiovascular causes as the lowest quintile, and for women about three times.
Next, take a look at the chart for total mortality, that is, death from all causes, not just cardiovascular disease. The same relation holds: the higher the resting heart rate, the greater risk of death.
For men, those with RHR >82 had about three times the death rate as those with RHR <60. For women, the same relation was about double.
These results were attenuated somewhat after the researchers adjusted their stats for waist size, smoking, blood pressure, diabetes, and physical activity, but remained highly significant, with total mortality increasing about 20% for each increase in RHR of 15 beats per minute, for both men and women.
The researchers comment:
The mechanism through which elevated RHR exerts its deleterious effect is unknown. Possibilities include predisposing to ischemia, arrhythmia, and plaque rupture or by promoting atherogenesis by increasing the absolute number of sheer stresses to which the vessel wall is exposed. Our demonstration of the stronger effect on fatal than nonfatal events supports proarrhythmogenicity as one of the mechanisms, as do previous studies showing a particularly strong effect of elevated RHR on sudden cardiac death. [Link added]
Curiously, although RHR is perhaps most strongly affected by one’s level of physical fitness, the association between RHR and death rates persisted even after adjusting for physical activity.
You can easily measure your resting heart rate.
First, find your pulse, either at your wrist or neck. Count the number of beats in 30 seconds, then multiply by two. This is best done in the morning in a calm state. If you take it at work or within a few hours after exercise, the reading likely won’t be accurate.
I took my RHR yesterday, and it was 46, putting me solidly in the lowest quintile. I wonder whether if the researchers had made their results more finely grained, and broke out the results for, say, those with RHR <50, whether risk would be even lower. My guess is that it would, since all the results in the study were graded, that is, for each rising quintile of RHR, death rates were higher.
In a chart showing what each level of RHR represents, my RHR falls into the category of “athlete” above “excellent”. (note that this chart doesn’t have any scientific references, so take that at face value — or not.)
An article at National Geographic says that a well-trained endurance athlete has a RHR of 40, and that Miguel Indurain, a five-time Tour de France winner, had a RHR of 28.
Back when I used to run long distance, I recorded a RHR of 32.
Besides obvious factors like losing fat and not smoking, the most important way to lower resting heart rate is through exercise.
While endurance exercise may be on record as producing the best results, to my knowledge, other exercise modalities haven’t been look at. For example, what is the Olympic sprinter Usain Bolt’s resting heart rate? Or that of an Olympic weightlifter? my guess is that they are all quite low.
Also, as we’ve previously seen, resistance training, especially when done at high intensity, produces an increase in VO2max, so that works too.
High-intensity interval training is also good for lowering RHR.
The key for lowering RHR is, just as for anything you want to improve, putting a stress on the body. Therefore, exercises like walking, while a healthy pursuit, may not do much to lower RHR; they simply don’t proviode enough stress to the system.
If you don’t already exercise, and want to undertake a program of RHR-lowering exercise, you should get a doctor’s clearance first, especially if you’re older and/or have pre-existing illnesses.