Middle-aged men with a resting heart rate of 75 beats per minute are twice as likely to die early and develop heart disease, scientists believe.
In a study published in the journal Open Heart, scientists analyzed 798 men living in the Swedish city of Gothenburg who were born in 1943. On three occasions, in 1993, 2003, and 2014, the participants underwent examinations including blood tests and ECGs to measure the electrical activity of their heart. They also filled out questionnaires on factors including their family heart health history and stress levels. In 2003, 654 men were still alive or agreed to take part again, and by 2014 536 hadn’t died and wanted to continue with the research.
The men were placed into four categories: those with 55 or fewer beats per minute, or bpm; between 56 to 65 bpm; 66 to 75 bpm; and over 75 bpm. Of the total men who took part, 119 died by 2014; 237 percent developed cardiovascular disease; and 113 coronary heart disease.
Resting heart rate describes the number of beats the organ completes per minute when a person isn’t exerting themselves. This figure can be calculated by checking the pulse, placing the index and third fingers on the neck beneath the jaw on the left-hand side, then counting the number of beats in 15 seconds. This figure is multiplied by four is the resting heart rate. A rate of 50 to 100 bpm, is considered normal.
In the study, those who were stressed; smokers; and/or had sedentary lifestyles were more likely to have a bpm higher than 55 at the start of the study. And men who had a resting heart rate of greater than 75bpm in 1993 were twice as likely to die, develop cardiovascular disease or coronary heart disease when compared with those who had a bpm of around 55, the authors found.
Meanwhile, the men who had a stable resting heart rate in the decade following 1993 were 44 percent less likely to develop cardiovascular disease compared with those whose resting heart rate increased over time.
In addition, an increase in resting heart rate from 1993 was linked with a 3 percent higher chance of death, 1 percent cardiovascular disease risk, and 2 percent coronary heart disease risk.
The researchers believe this could be because a high resting heart rate may put the heart under stress and increase oxygen consumption. It has also been linked to sympathetic overactivity, where the nervous system works too hard, which is tied to conditions that affect the heart such as high blood pressure and metabolic syndrome.
Dr. Salim Bary Barywani, of the department of molecular and clinical medicine at the University of Gothenburg, told Newsweek future studies should look at individuals up to the age of 90, measure the heart rate more frequently, and feature women so the results can relate to wider populations.
Ashleigh Li, a senior cardiac nurse at the British Heart Foundation charity who was not involved in the research, told Newsweek: "This study seems to suggest a link between having a higher resting heart rate and your chance of developing heart and circulatory disease. However, this research is limited. It only shows that a link may exist, it can’t tell us why.
“As the study only involved men, we need a lot more data to really investigate whether this link is true for all of us— men and women of any age.
“There are certain risk factors, such as blood pressure and cholesterol levels, that we know are linked to an increased risk of heart attack and stroke. We can all do something about these by eating a healthy, balanced diet, cutting down on salt and being more active. This research should serve as a reminder for us all to know our numbers, blood pressure, cholesterol and weight, as well as our resting heart rate.”
Worldwide, around 17.9 million people die each year because of some form of cardiovascular disease, according to the World Health Organisation. That amounts to 31 percent of all deaths. In the U.S., it is the cause of one in four deaths, or 610,000 people each year.
Earlier this year, a separate study found men who could complete more than 40 push-ups had a 96 percent lower risk of experiencing heart disease and stroke. The researchers at the Harvard T.H. Chan School of Public Health published the findings of their study in the journal JAMA Network Open.