Introduction Increased sedentary behavior predicts greater cardiovascular morbidity and mortality, and does so independently of physical activity (PA). This association is only partially explained by BMI and overall body fat, suggesting mechanisms besides general increased adiposity. The purpose of this study was to explore associations of self-reported leisure PA and sitting time with regional fat depositions and abdominal muscle among community-dwelling older adults. Methods Participants were 539 diverse adults (mean age 65) who completed a study visit in 2001-2002. Areas of pericardial, intra-thoracic, subcutaneous, visceral, and intermuscular fat, as well as abdominal muscle, were measured using computed tomography. Leisure PA and sitting hours were entered simultaneously into multivariate regression models to determine associations with muscle and fat areas. Results After adjusting for demographics, smoking, diabetes, hypertension, triglycerides, and cholesterol, greater PA was associated with less intra-thoracic, visceral, subcutaneous, and intermuscular fat (for all p < .05), while greater sedentary time was associated with greater pericardial and intra-thoracic fat (for both p < .05). After further adjusting for BMI, each hour of weekly PA was associated with 1.85 cm2 less visceral fat (p < .01), but was not associated with other fat depositions. Conversely, each hour of daily sitting was associated with 2.39cm2 more pericardial fat (p < .05), but was not associated with any other fat depositions. There were no associations with abdominal muscle area. Adjusting for common inflammatory markers had little effect. Associations between fat and PA were stronger for men. Conclusions Sitting and physical activity have distinct associations with regional fat deposition in older adults. The association between sitting and pericardial fat could partially explain the link between sitting and coronary heart disease.

In older women, abdominal muscle area is inversely associated with type II diabetes independent of visceral adiposity, particularly for normal weight women.

Objective Pericardial and intra-thoracic fat are associated with prevalent cardiovascular disease (CVD) and CVD risk factors. However, it is unclear if these fat depots predict incident CVD events and/or all-cause mortality. We examined prospective associations between areas of pericardial and intra-thoracic fat and incident CVD and mortality over a 12-year follow-up in a subset of participants without baseline clinical CVD from the Rancho Bernardo Study (RBS). Methods Participants were 343 community-dwelling older adults (mean baseline age=67) who completed a clinic visit in 2001–02, including a computed tomography scan of the chest. Incident CVD and mortality were recorded through January 2013. Results Over a 12.6-year median follow-up, there were 60 incident CVD events and 49 deaths. Pericardial fat was associated with all-cause mortality, such that each standard deviation increment predicted a 34% higher chance of death after adjusting for demographics, lifestyle factors, comorbidities, and visceral fat (95% CI=1.01–1.78). When categorized by tertile, those in the middle tertile of pericardial fat showed no increased risk of mortality, while those in the highest tertile had 2.6 times the risk (95% CI=1.10–5.97) compared to the lowest tertile. There was a marginal association between intra-thoracic fat and mortality (p=0.06). Neither pericardial nor intra-thoracic fat was significantly associated with incident CVD. There were no significant interactions by sex. Conclusions Higher pericardial, but not intra-thoracic, fat was associated with earlier all-cause mortality in older adults over a 12-year follow-up. This association was primarily driven by a higher mortality rate in those in the highest tertile of pericardial fat.

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