Being inactive is solidly linked to heart problems like heart attack and stroke, and exercise can help lower risk factors—such as high blood pressure and narrowed blood vessels—that are connected to those heart events.
But when it comes to another type of heart condition, heart failure, the effect of physical activity isn’t as clear. If coronary heart disease can be traced to more physical issues, such as blocked arteries or excessive pressure from blood pumping around the body, heart failure is more of a body-wide problem affecting not just the heart but almost every tissue. In heart failure, the heart gradually loses its ability to effectively pump oxygen-rich blood to the rest of the body, and it can’t keep up with supplying muscles and cells with what they need to function properly. 5.1 million people in U.S. have heart failure.
In the latest study, Jarett Berry, associate professor of medicine and clinical sciences at University of Texas Southwestern Medical Center, and his colleagues studied how exercise can affect risk of heart failure. They report in the journal Circulation on how much physical activity is needed to effectively lower risk of the condition.
Berry and his team analyzed responses from 12 large studies involving 370,460 people who were asked about their exercise habits and followed on average for 13 years. Berry found that those who were the most physically active showed a 30% lower risk of having heart failure than those who exercise the least. These people got more activity than what the government currently recommends, which is 150 minutes of moderate physical activity each week. The people who exercise that much also lowered their risk of heart failure, but not by as much: a 15% to 22% drop.
In fact, people who doubled the recommended level of activity lowered their risk of heart failure by 19% while those who quadrupled the amount of exercise reduced their risk by 35%.
“We didn’t start seeing 30% to 40% reduction in risk until the people were out at three times to four times the recommended amount of exercise,” says Berry. “So higher doses of exercise aren’t a waste of time in preventing heart failure.”
Berry stresses that while the people who exercised more clearly derived more benefit from the activity, any amount of exercise is still helpful. Compared to people who were not active at all, those who followed the recommended 150 minutes of activity a week lowered their risk of heart failure by 10%.
The findings do suggest, however, that exercise advice to lower heart failure may be different from recommendations for reducing heart attacks and stroke. That may be because the two categories of heart problems are caused by different factors. “Heart attacks are caused by blocked arteries in the heart that lead to chest pain and damage heart muscle,” says Berry. “Heart failure is more insidious, and the underlying problems it generates are not nearly as specific.”
High blood pressure and obesity are major drivers of both heart attacks and heart failure. But while heart attacks can be traced to specific obstructions in the heart vessels, heart failure can show up in the form of shortness of breath, kidney failure or swelling in the feet.
While previous studies had hinted at the benefit of exercise for preventing heart failure, and even for helping heart failure patients to recover, there was little data about whether the current recommended amount of exercise—the same 150 minutes per week advised for heart attack prevention—was enough. Heart failure patients often have shortness of breath and can’t exercise much, which can make physical activity challenging. “For a long time, the dogma in cardiovascular medicine was that when people were sick with heart failure, they should have bed rest,” says Berry. “But that commonsensical approach turned out not to be true.”
The study alone won’t be enough to change the recommendations for heart failure patients, and Berry notes that it highlights a possible connection between exercise and heart failure. Further studies in which people are randomly assigned to exercise beyond the recommended amount and at the recommended level need to be done. But it should give doctors more confidence in advising their patients to gradually build up to higher amounts of physical activity if they want to protect themselves from the condition. All of the people in the study were healthy and did not yet have any signs of heart trouble, but given the rising prevalence of heart failure as the population ages, having a possible preventive strategy in the form of exercise may be critical in bringing rates down. Understanding that methods for preventing heart attacks may be different from those for preventing heart failure may also be essential to saving more lives.