Sedentary Behavior, Physical Activity, and Abdominal Adipose Tissue Deposition.

PURPOSE: We examined whether sedentary lifestyle habits and physical activity level are associated with abdominal visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), intermuscular adipose tissue (IMAT), and liver attenuation, independently of one another and potential confounders.
METHODS: This study analyzed 3010 African American and Caucasian men and women, 42-59 yr old, from the Coronary Artery Risk Development in Young Adults (CARDIA) study, who completed multiple-slice abdominal computed tomography in 2010-2011. Participants reported average hours per day sitting (television, computing, paperwork, music, telephone, and car). Physical activity was assessed with the CARDIA physical activity history. VAT, SAT, IMAT, and liver attenuation were estimated from computed tomography. Multivariable general linear regression models regressed means of fat depots on total sedentary time, task-specific sedentary time, and total physical activity.
RESULTS: Television viewing was positively, and physical activity inversely, associated with fat depots. For each 1 SD increment in television viewing (1.5 h·d), VAT, SAT, and IMAT were greater by 3.5, 3.4, and 3.9 cm, respectively (P < 0.03 for all). For each 1 SD increment in physical activity (275 exercise units), VAT, SAT, and IMAT were lower by 7.6, 6.7, and 8.1 cm, respectively, and liver attenuation was greater (indicating more liver fat) by 0.5 Hounsfield units (P < 0.01 for all). Total sedentary time was associated with VAT, IMAT, and liver attenuation in White men only after controlling for physical activity, SAT, and other potential confounders (P ≤ 0.01 for all). No other task-specific sedentary behaviors were associated with fat depots.
CONCLUSIONS: Sedentary behaviors, particularly television viewing, and physical activity levels have distinct, independent associations with fat deposition.