Physical Activity and Novel Cardiac Risk Markers in Healthy Older Adults

Background The mechanisms underlying the cardia-protective effects of physical activity in older adults remain poorly understood. We examined the relationship between objectively measured physical activity during free-living and novel cardiac risk markers, including coronary artery calcium (CAC) and pericardial fat (PF).

Methods Participants were 446 healthy men and women (mean age=66±6 yrs), without history or objective signs of coronary heart disease, drawn from the Whitehall II epidemiological cohort. Physical activity was objectively measured using accelerometers (Actigraph GT3X) worn around the hip during waking hours for 7 consecutive days. Electron beam computed tomography was used to measure CAC and PF.

Results Average daily counts per minute (cpm) in men was 338.0±145.0 and in women 303.8±130.2. There was an inverse association between average cpm and pericardial fat (B=-0.070, 95% Cl, -0.101 to -0.040, p<0.001), and this remained significant after adjusting for age, sex, registered wear time, body mass index, and other risk factors. Both sedentary time (B=0.081, 95% Cl, 0.022 to 0.14) and moderate-vigorous activity (MVPA) (B=-0.362, 95% Cl, -0.527 to -0.197) were also associated with pericardial fat, although associations for sedentary time did not remain significant after adjustment for MVPA. There was no association between physical activity and presence of detectable CAC.

Conclusions Objectively assessed daily activity levels are related to pericardia! fat in healthy participants. The null findings relating to CAC suggest that physical activity might be less predictive of advanced coronary atherosclerosis, although further studies are required that employ better measures of plaque stability.