Associations of Physical Activity and Sedentary Behavior with Regional Fat Deposition

Abstract

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.

The association between objectively measured sitting and standing with body composition: a pilot study using MRI

“…Previous studies have attempted to investigate these associations, but without the benefit of the existing gold standard techniques for body composition or full postural allocation measurements. In a recent study using CT, self-reported leisure-time sitting was associated with pericardial fat, but not with any other fat depots 16. We have previously reported associations between objectively assessed sedentary time (Actigraph) and pericardial fat although the relationship did not persist after adjusting for MVPA 17.…”

Physical Activity and Abnormal Blood Glucose Among Healthy Weight Adults

“…[26][27][28] Historically, the focus of Type 2 diabetes prevention and treatment programs has been primarily on calorie restriction and weight loss. However, this study and others suggest that physical activity, not solely weight loss, provides the protective and therapeutic effects on blood glucose levels.…”

Exercise, Blood Pressure and Mortality: Findings of Eight Years of Follow-Up

“…A number of studies have reported that exercise reduces blood pressure in both hypertensive and normotensive subjects [12][13][14] . Although the mechanisms by which regular exercise reduces blood pressure are not completely clear [15][16][17] , the benefits of physical activity may accrue through reduction of other cardiovascular risk factors, such as improved glucose tolerance 18 or lower BMI and visceral fat 19 , resulting in a lower occurrence of comorbidities associated with hypertension 20 . In addition, long-term regular physical activity preserves cardiac compliance 21 , endothelial regulation of smooth muscle tone and other aspects of vascular wall structure/function 22 , workload and cardiac performance 23 .…”