How much harm is done - and how quickly - by failing to maintain an exercise program? How long does it take to reverse those consequences? No-one has the final answer to those questions, firm numbers derived from the way in which the human body functions. We can look at the results of studies such as this one with some interest, however. We might compare this with studies of weight and mortality, in which the evidence suggests that lasting harm is done by carrying excess fat tissue over years, even if lost later.
By analyzing reported physical activity levels over time in more than 11,000 American adults, researchers conclude that increasing physical activity to recommended levels over as few as six years in middle age is associated with a significantly decreased risk of heart failure. The same analysis found that as little as six years without physical activity in middle age was linked to an increased risk of the disorder. "In everyday terms our findings suggest that consistently participating in the recommended 150 minutes of moderate to vigorous activity each week, such as brisk walking or biking, in middle age may be enough to reduce your heart failure risk by 31 percent. Additionally, going from no exercise to recommended activity levels over six years in middle age may reduce heart failure risk by 23 percent."
The researchers caution that their study was observational, meaning the results can't and don't show a direct cause-and-effect link between exercise and heart failure. But the trends observed in data gathered on middle-aged adults suggest that it may never be too late to reduce the risk of heart failure with moderate exercise. "Unlike other heart disease risk factors like high blood pressure or high cholesterol, we don't have specifically effective drugs to prevent heart failure, so we need to identify and verify effective strategies for prevention and emphasize these to the public." There are drugs used to treat heart failure, such as beta blockers and ACE inhibitors, but they are essentially "secondary" prevention drugs, working to reduce the heart's workload after dysfunction is already there.
The researchers used data already gathered from 11,351 participants in the long term Atherosclerosis Risk in Communities (ARIC) study, recruited from 1987 to 1989. The participants' average age was 60, and 57 percent were women. Participants were monitored annually for an average of 19 years for cardiovascular disease events such as heart attack, stroke, and heart failure using telephone interviews, hospital records and death certificates. Over the course of the study there were 1,693 hospitalizations and 57 deaths due to heart failure.
In addition to those measures, at the first and third ARIC study visits (six years apart), each participant filled out a questionnaire, which asked them to evaluate their physical activity levels, which were then categorized as poor, intermediate or "recommended," in alignment with guidelines issued by the American Heart Association. The "recommended" amount is at least 75 minutes per week of vigorous intensity or at least 150 minutes per week of moderate intensity exercise. One to 74 minutes per week of vigorous intensity or one to 149 minutes per week of moderate exercise per week counted as intermediate level activity. And physical activity qualified as "poor" if there was no exercise at all.
Heart failure risk decreased by about 12 percent in the 2,702 participants who increased their physical activity category from poor to intermediate or recommended, or from intermediate to recommended, compared with those with consistently poor or intermediate activity ratings. Conversely, heart failure risk increased by 18 percent in the 2,530 participants who reported decreased physical activity from visit one to visit three, compared with those with consistently recommended or intermediate activity levels.