Physical activity intensity and cardiovascular risk by ankle-brachial index

A low ankle-brachial index (ABI) is associated with increased risk for cardiovascular events and mortality. Physical inactivity in individuals with a low ABI may further increase their risk for cardiovascular events. The purpose of this paper is to examine the relationship between the intensity of free-living physical activity and cardiovascular disease (CVD) risk by ABI status. During 2003-2004, the National Health and Nutrition Examination Survey included an accelerometer module and collected ABI data. Individuals were classified as having a normal (1-1.4) or low (< 1) ABI. The Framingham risk score (FRS) was used to determine CVD risk. Multiple linear regression was used to determine the association of total accelerometer counts and time spent at various physical activity intensity levels with FRS by ABI groups. Individuals with a low ABI spent less time engaging in moderate-to-vigorous intensity physical activity (MVPA) (9.1 min/day vs 13.2 min/day; p = 0.06) when compared to those with a normal ABI. There were no differences in light intensity physical activity (LPA) or sedentary behavior between ABI groups. Total accelerometer counts were inversely related to FRS. MVPA, but not LPA, was inversely related to FRS in both normal and low ABI groups (p < 0.001 and p = 0.001, respectively). In conclusion, these findings suggest that even modestly higher levels of physical activity may be beneficial for secondary risk prevention in this high-risk group.