Associations of physical activity and sedentary behavior with regional fat deposition.
BACKGROUND
Increased sedentary behavior predicts greater cardiovascular morbidity and mortality and does so independently of physical activity (PA). This association is only partially explained by body mass index (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 yr) who completed a study visit in 2001-2002. Areas of pericardial, intrathoracic, 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 intrathoracic, visceral, subcutaneous, and intermuscular fat (for all P < 0.05), while greater sedentary time was associated with greater pericardial and intrathoracic fat (for both P < 0.05). After further adjusting for BMI, each hour of weekly PA was associated with 1.85 cm less visceral fat (P < 0.01) but was not associated with other fat depositions. Conversely, each hour of daily sitting was associated with 2.39 cm more pericardial fat (P < 0.05) 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 PA 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.
1Department of Family and Preventive Medicine, University of California, San Diego, San Diego, CA; and 2Department of Epidemiology, University of Pittsburgh, Pittsburgh, PA.
Britta A
BA
Larsen
Matthew A
MA
Allison
Eugene
E
Kang
Sarah
S
Saad
Gail A
GA
Laughlin
Maria Rosario G
MR
Araneta
Elizabeth
E
Barrett-Connor
Christina L
CL
Wassel
D000368:Aged; D000886:Anthropometry / Q000379:methods; D050218:Body Fat Distribution; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D057185:Sedentary Behavior; D057566:Self Report