People often look to
their resting heart rate as a marker of their fitness: While a normal resting heart rate
is between 60 to 100 beats per minute, endurance athletes can have one
that is quite a bit lower.
But can your resting heart rate hint at something more serious—like your life expectancy?
That’s what researchers from Harvard Medical School are suggesting, after publishing research linking earlier death to an increase in resting heart rate.
In the 28-year study, researchers measured the heart rates of over 15,000 people at subsequent doctor appointments. They discovered that for every five beats per minute increase from one visit to the other—an average of three years between them—people’s risk of death by any cause increased by 12%, heart failure by 13%, heart attack by 9%, stroke by 6%, cancer by 8%, and death by heart disease by 13%. A decrease in resting heart rate, on the other hand, was linked to lower risk.
"Heart rate is actually a very good barometer of overall fitness and cardiovascular health. As we become less fit, our heart rates tend to go up, both at rest and with exertion," says study author Scott D. Solomon, MD, professor of medicine at Harvard Medical School.
So how exactly does an increase in resting heart rate increase your risk of heart attack, or even cancer?
First, it’s likely that heart rate is simply a marker of declining physical fitness and reduced cardiovascular health, Solomon says.
“In addition, elevated heart rate itself may indeed cause the heart to 'require' more oxygen, and can lead to ischemia—a lack of oxygen—and contribute to heart attacks," says Solomon
MORE: 6 Guys Who Suffered a Heart Attack Reveal What It Really Feels Like
When it comes to cancer, though, the link to resting heart rate is a little more tricky to explain.
But the study found that changes in resting heart rate increased the activation of sympathetic nervous system, which is responsible for your body's fight-or-fight hormonal response. That’s been directly related to the development of certain diseases, including cancer.
It’s also possible that people with cancer simply have increased metabolic needs, which might elevate their heart rate, says Solomon. That—on top of their cancer diagnosis—puts them at a higher risk of earlier death.
What Your Resting Heart Rate Means For You
"The data suggests that heart rate going up five points (on average) does increase risk, even if that is within the 'normal' range," says Solomon. That means you should pay attention to any sustained increase from your baseline, even if your resting heart rate is still within that normal 60 to 100 beats per minute range.
So it's important to have the data on your heart rate to determine how your overall health is, and to recognize that heart rate changes throughout the day and based on activity.