It’s no secret that heart disease is the number one killer in the United States, by quite a significant margin. According to the CDC, Heart disease killed 633,842 people in 2015, and cancer came in second at 595,930 deaths. The next was a significant drop — 155,041 deaths due to chronic lower respiratory diseases. That’s quite the difference. The American Heart Association says that they attribute “about 1 of every 3 deaths in the US” to heart disease.

It’s also no secret that a consistent regimen of cardio can greatly reduce the risk of heart disease. A study from Stanford followed several elderly Americans for over 20 years, and they studied both runners and non-runners. The non-runners not only developed disabilities on an average of 16 years earlier than the runners, but the runners were about half as likely to die early deaths when compared to the non-runners. And these aren’t super-athletes running marathons in their spare time, some of them could only manage just over an hour of exercise a week due to old age.

Depression has also been linked to the fatality rates of heart disease. Of course, someone who is depressed might be less inclined to take proper medication and will also probably not be out running or lifting weights as often. However, it also appears as if depression has a direct link to the physical onset of heart disease. Dr. Jesse C. Stewart, Associate Professor at Indiana University-Purdue University Indianapolis said that, “Thirty years of epidemiological data indicate that depression does predict the development of heart disease.”

Despite the cause, depression is inextricably linked to heart disease. According to the National Heart, Lung and Blood Institute, “adults with a depressive disorder or symptoms have a 64 percent greater risk of developing coronary artery disease (CAD); and depressed CAD patients are 59 percent more likely to have a future adverse cardiovascular event, such as a heart attack or cardiac death.”

A new study by The Cooper Institute in Dallas was published on the correlation between cardiorespiratory fitness, depression and heart disease on June 27. The study aimed to determine whether more cardiorespiratory fitness (running, swimming, cycling, etc.) had a significant effect on the number of cardiovascular disease-related deaths, after depression had been diagnosed beyond the age of 65. Their findings were significant:

…higher levels of fitness in midlife were associated with a 16% lower risk of depression. In addition, after a diagnosis of depression, higher levels of fitness were associated with a 56% lower risk of cardiovascular mortality.”

Which essentially means that,

Men and women who are more physically fit at midlife have a lower risk of depression and cardiovascular mortality after a diagnosis of depression in later life, suggesting that fitness is an important part of a primary preventive strategy for cardiovascular disease and depression across the lifespan.”