Going from 70 beats per minute to over 85 over a decade increases a person’s risk of dying from heart disease by 90 percent, a large study claims. The findings were published in the Journal of the American Medical Association.

About 30,000 study subjects in Norway were followed for 12 years. None of the men or women had heart disease when the study began, and their average age at the start was 52. By the end of the study, over 3,000 had died – and 400 of these deaths were from heart disease.

Changes in resting heart rate may indicate underlying heart disease not yet recognized – and a need for lifestyle changes, said study senior author Ulrik Wisloff, director of the K.G. Jebsen Center of Exercise in Medicine in Trondheim, Norway.

Age, activity level, diet, tobacco use, and family history may influence a person’s heart rate. Obesity also may play a role, as it stresses the heart and circulatory system.

Generally speaking, a slower resting heart beat indicates better heart health.

“Resting heart rate is one of the simplest measures in medicine and everyone can do that by themselves at home,” Wisloff said.

To check your resting heart rate, check your pulse when at rest. Begin with your palm up, then place two fingers on the thumb side of your wrist. Count the number of beats you feel in a 10-second period of time. Multiply this number by six to get your average beats-per-minute.