Studies have shown that physical activity has a positive impact on the prevention of cardiovascular disease in the general population. Other studies have shown that physical activity can reduce overall mortality rates and decrease the incidence of cardiovascular disease and diabetes. Activity levels (from moderate to very high impact), durations, and types have been shown to have varying effects on cardiovascular disease prevention. However, these studies do not clarify the effect of physical activity level on life expectancy or on delaying the onset of cardiovascular disease. Franco and colleagues evaluated the impacts of different levels of physical activity on life expectancy and years lived with or without cardiovascular disease.
The data used in the study were from the Framingham Heart Study, which enrolled respondents from 1948 through 1951 and followed them biannually for 46 years. The data were analyzed from three different follow-up periods (four, 11, and 19 years). The participants were asked to estimate how long they spent on various levels of activities, including sleeping, resting, or participating in light, moderate, or heavy physical activity. A daily physical activity score was calculated using 1.0 point for sleep, 1.1 for sedentary activity, 1.5 for light activity, 2.4 for moderate activity, and 5.0 for heavy activity. Using these scores, the participants were divided into three activity groups: light, moderate, and high. The outcome measures that were evaluated in the study were incidence of cardiovascular disease or fatal cardiovascular events. Other variables such as age, sex, smoking, any comorbidities, and examination at baseline also were included in the analysis.
There were 4,121 participants in the study at the first interval (year 4), 3,260 at the second interval, and 1,652 at the third interval. After controlling for other variables, moderate physical activity was found to increase life expectancy by 1.3 years and delay the onset of cardiovascular disease by 1.1 years in men 50 years and older compared with those who were sedentary. When comparing those with high physical activity with those who were sedentary, the high activity group had an increased life expectancy of 3.7 years and 3.2 more years free of cardiovascular disease. The effect of moderate or high physical activity in women 50 years and older showed similar positive effects.
The authors conclude that moderate or high levels of physical activity improve life expectancy and increase the cardiovascular disease-free period in men and women. They add that this positive effect is seen at moderate exercise levels and is even better at high levels of physical activity. In an accompanying editorial, Blair and LaMonte point out that individuals who wish to exercise at a high level of intensity (heart rate 65 to 75 percent of maximum) can obtain improvements in their fitness by walking for 30 minutes three or four times per week. Those who prefer a low-intensity activity (45 to 55 percent maximum heart rate) can achieve the same level by walking for 30 minutes five to seven days per week.