Resting Heart Rate Fell in Norway, Rebounded in Belfast

Not everywhere. In the Tromsø Study in Norway, 30,699 adults were followed across four surveys from 1986 to 2007. Age-adjusted resting heart rate fell from 73.4 to 64.7 beats per minute in men and from 78.3 to 66.4 in women, across all ages. In 5,562 Belfast first-year students from 1949 to 2004, heart rate declined until the mid-1980s and then rose. The Norwegian drop tracked improving blood pressure, triglycerides and activity.

Did average resting heart rate fall in Norway?

Yes, by a lot. The Tromsø Study followed 30,699 men and women aged 30 to 89 who took part in at least one of the surveys in 1986, 1994, 2001 and 2007. The study was single-center and population-based.

Age-adjusted average resting heart rate fell from 73.4 to 64.7 beats per minute in men. It fell from 78.3 to 66.4 in women. The drop is about 8.7 beats in men and 11.9 in women, the arithmetic difference of the published means.

The decline continued from one survey to the next. It was of similar size in both sexes, at all ages and across birth cohorts.

What changed along with it?

Several risk factors. The decline was larger in people who moved from adverse to favorable blood pressure, total and HDL cholesterol, triglycerides, body mass index, smoking and physical activity. It was also larger in those who started blood pressure medication.

The strongest predictors of an individual's decline were a fall in systolic blood pressure and triglycerides, more physical activity, taking blood pressure treatment and quitting smoking.

The authors say the decline is only partly related to those changes, and that the reasons need further study. They suggest new definitions of normal resting heart rate may be needed.

Is the trend the same everywhere?

No. A series of cross-sectional surveys of 5,562 first-year students aged 16 to 24 at Queen's University Belfast ran from 1949 to 2004. Heart rate declined through the 1950s. From 1975, adjusting for age, body mass index, height and smoking, it followed a U shape in both sexes. It declined first and then increased from the mid-1980s.

The rise was not explained by rising overweight. Heart rate in the 693 men (28%) reporting the most physical activity stayed stable and lower than in less active men. Women who were most active also had lower heart rates.

The authors say the recent rise raises concern that favorable cardiovascular trends may not be maintained. It is a different population and age group from Tromsø.

Does the number matter for health?

In cohort data, higher resting heart rate goes with higher mortality risk. A 46-study meta-analysis found a relative risk of 1.09 for all-cause death per 10 beats per minute. See resting heart rate and longevity.

A review notes a clear association in longitudinal work between rising heart rate over time and adverse events. It also cites Mendelian randomization work that suggests a causal link between resting heart rate and longevity. That claim is the review's, and the abstract does not give a figure.

What lowers the number is covered in how to lower resting heart rate. What counts as elevated is in elevated resting heart rate.

What does wearable data show today?

A snapshot, not a trend. A study followed 92,457 adults wearing trackers for about two years. Mean daily resting heart rate was 65 beats per minute, with a range of 40 to 109. It varied by season, with the lowest in July and the highest in January.

That study followed people for two years. It cannot show whether average resting heart rate has kept falling since Tromsø's last survey in 2007. How devices measure the number is in how wearables measure resting heart rate.

What does this not settle?

The Norwegian decline comes from one town, with data through 2007. It says nothing about later years or other countries. The Belfast series shows a different path in young adults.

The Tromsø authors say the fall is only partly related to the risk factor changes and that the reasons need to be further elucidated.

Common questions