Researchers here crunch the numbers to suggest that people who exercise for longer are better off in terms of risk of suffering age-related cardiovascular disease. One of the emerging themes in epidemiology in recent years is an attempt to pin down the dose-response curve for exercise. How is long term health and life expectancy affected for different levels of exercise, and do these differences reflect correlation or causation? Is it a matter of people obtaining health benefits through exercise or a matter of more healthy people tending to exercise more? These are hard questions to answer for human populations, but as technology lowers the cost of obtaining and using large data sets, ever more research groups are taking a stab at it. As with all such statistical studies, it is wise to wait for more data and the work of different teams before taking anything published by one group at face value, however:
Doubling or quadrupling the minimum federally recommended levels of physical activity lowered the risk of developing heart failure by 20 percent and 35 percent, respectively, according to researchers. "Walking 30 minutes a day as recommended in the U.S. physical activity guidelines, may not be good enough - significantly more physical activity may be necessary to reduce the risk of heart failure." The researchers found that the current U.S. physical activity guidelines recommendation of a minimum of at least 150 minutes of moderate intensity physical activity a week was associated with only a modest reduction in heart failure risk, and suggest that higher levels of physical activity, up to twice the minimum recommended dose, is needed to reduce the risk of heart failure.
They also found a "dose-dependent" inverse association between physical activity and heart failure, that is, higher levels of physical activity were associated with a lower risk of heart failure. This relationship was consistent across all age, sex, race, and geographic location based subgroups studied. Although the role of physical activity in coronary heart disease - the narrowing of the arteries that causes heart attacks - has been comprehensively studied, this study focused exclusively on the quantitative relationship between the amount, or specific "dose" of regular physical activity and the risk of heart failure.
The researchers pooled data from 12 studies from United States and Europe that collectively included 370,460 individuals with varying levels of physical activity at baseline and 20,203 heart failure events over a mean follow-up of 15 years. Physical activity was measured by self-reported levels of activity by study participants using standard questionnaires. "Future physical activity guidelines should take these findings into consideration, and potentially provide stronger recommendations regarding the value of higher amounts of physical activity for the prevention of heart failure."