Purpose
Physical inactivity is a risk factor for many diseases, including cardiovascular disease. However it is unknown whether being physically active might increase longevity in persons with and without cardiovascular disease. To address this question, Franco and colleagues (Archives of Internal Medicine, 2005; 165:2355-2360) calculated the consequences of different levels of physical activity on life expectancy in adults after the age of 50.
Methods
Data from the longitudinal Framingham Heart Study were used to construct multi-state life tables based on three different levels of physical activity (based on estimates of oxygen consumption and categorized as low moderate, and high) among populations aged over 50 years. For these calculations, hazard ratios were used for three health transitions (healthy to death, healthy to disease, and disease to death) by level of physical activity and adjusting for age, sex, smoking, selected medical co-morbidities (for example, cancer, arthritis, diabetes, pulmonary disease), and physical examination at the start of follow-up.
Results
Compared to a low level of physical activity, it is estimated that moderate and high levels of physical activity produced a 1.3 and 3.7 year increase in total life expectancy in men, respectively. For women, moderate and high physical activity levels were estimated to produce a 1.5 and 3.5 difference in life expectancy, respectively. Moderate and high levels of physical activity also led to 1.1 and 3.2 more years lived without cardiovascular disease among men, and 1.3 and 3.3 years among women, respectively.
Conclusions
Being physically active appears to increase total life expectancy and cardiovascular disease-free years for both men and women. A dose-response association was observed in that high levels of physical activity produced about two times as large the benefits in life expectancy as did moderate activity levels.
Editorial Comments
The results of this epidemiologic study indicate that maintaining a physically active lifestyle appears to promote an increase in life expectancy, as well as an increase in years without cardiovascular disease. These results support the physical activity recommendations of the US Surgeon General, the American College of Sports Medicine, the American Heart Association, and other organizations interested in public health. Although this study suggests strongly that physical activity associates with increased longevity, independent of the effects of sex, age, smoking, and co-morbid medical conditions, several limitations prohibit definitive causal statements (that is, Being physically active causes increased life expectancy.). First, it is possible that individuals with low levels of physical activity were already ill or were experiencing sub-clinical disease that prevented physical activity. In other words, it was not being physically active that promoted increased life expectancy it was illness that promoted physical inactivity. Second, physical activity levels were based on self-report and not verified objectively. Third, it is possible that other factors not assessed but associated with being physically active (most notably eating a healthy diet) drive the association between physical activity and increased life expectancy. Despite these limitations, this study provides evidence that a physically active lifestyle may assist older adults in maintaining their general and cardiovascular health.
