Resting heart rate on the decline: the Tromso Study 1986-2007

Background: We examined secular changes in resting heart rate (RHR) and their relationship with changes in other cardiovascular risk factors in adult men and women over a 22-year period. Methods: A single-centre population-based longitudinal study comprised 30 699 men and women aged 30-89 years who participated in at least one of the 1986, 1994, 2001 and 2007 surveys of the Tromso Study, Tromso, Norway. Results: During the study period, the age-adjusted means of RHR declined from 73.4 to 64.7 beats per minute (b.p.m.) in men, and from 78.3 to 66.4 b.p.m. in women. The decline was persistent from one survey to the next and was of similar size in both sexes and for all age groups and birth cohorts. RHR declined gradually over time for different levels of cardiovascular risk factors, and it declined more in those who moved from adverse to favourable values or categories of blood pressure, total and high-density lipoprotein cholesterol, triglycerides, body mass index, smoking and physical activity, and those who started to take blood pressure medication. The strongest predictors of individual decline in RHR were decrease in systolic blood pressure and triglycerides, increase in physical activity, taking blood pressure treatment and smoking cessation. Conclusion: A considerable decline in RHR has occurred in Tromso over the past two decades in men and women of all ages. The decline is partly related to changes in several cardiovascular risk factors, and reasons behind this need to be further elucidated. The findings suggest that new definitions of normal RHR may be needed.