Associations between accelerometer-derived physical activity and regional adiposity in young men and women

Abstract

Objective Empirical evidence supports an inverse relationship between physical activity (PA) and adiposity, but studies using detailed measures of both are scarce. We described the relationship between regional adiposity and accelerometer-derived PA in men and women. Design and Methods Cross-sectional analysis included 253 participants from a weight loss study limited to ages 20–45 years and BMI 25–39.9 kg/m2. PA data were collected with accelerometers and expressed as total accelerometer counts and average amount of time per day accumulated in different intensity levels (sedentary, light-, and moderate- to vigorous- intensity PA (MVPA)). Accumulation of time spent above 100 counts was expressed as total active time. Computed tomography (CT) was used to measure abdominal and adipose tissue (AT). Multivariate linear regression analyses were used to assess the relationship between regional adiposity (dependent variable) and the various PA levels (independent variable), and were executed separately for men and women, adjusting for wear time, age, race, education, and BMI. Results Among males light activity was inversely associated with total AT (β=−0.19; p=0.02) as well as visceral AT (VAT) (β=−0.30; p=0.03). Among females sedentary time was positively associated with VAT (β=0.11; p=0.04) and total active time was inversely associated with VAT (β=−0.12; p=0.04). Conclusions Findings from this study suggest that PA intensity level may influence regional adiposity differently in men and women. Additional research is needed in larger samples to clarify the difference in these associations by sex, create recommendations for the frequency, duration and intensity of PA needed to target fat deposits, and determine if these recommendations should differ by sex.

Sedentary Behavior, Physical Activity, and Abdominal Adipose Tissue Deposition

“…Our findings are consistent with other, smaller studies that have also reported sex differences when examining the association between sedentary behaviors and abdominal fat deposition (13, 26, 31). For example, Henson and colleagues reported positive associations between accelerometer measured sedentary time and magnetic resonance imaging measured VAT and liver fat in a sample of 66 White men and women at risk for type 2 diabetes (13).…”

“…A study by Yim and colleagues found stronger associations between IMAT and glucose, protein bound glucose, and total cholesterol than observed for VAT (33). Adverse associations have also been reported between liver fat and fasting glucose and triglycerides, independent of other fat depots (31). In our study, we found that among White men, total sedentary time and television viewing were adversely associated with IMAT and liver attenuation, while the opposite associations were observed for physical activity and these fat depots in the entire cohort.…”

“…Some evidence suggests a positive association between sedentary time and VAT (13, 26, 31), while other studies report no association (20, 22, 29). To our knowledge, only one study has examined the associations between sedentary behavior and liver fat (13), or sedentary behavior and abdominal IMAT (20), two fat depots that may be independent predictors of metabolic risk (27, 33).…”

Associations of Objectively Measured Physical Activity and Abdominal Fat Distribution

“…This finding is also in agreement with previous evi dence that SED is positively associated with waist circum ference independent of MVPA (10). A further study of 2056 European healthy middle-age adults found a positive as sociation between SED measured using accelerometry and anthropometric measures including waist circumference (32), and Smith et al (22) found a significant positive as sociation between SED and VAT in women. Other studies did not find such associations, but these are characterized by smaller study samples and/or self-reported PA assess ment (15,20).…”

“…In a cross-sectional analysis of 253 young adults, Smith et al (22) found that PA volume assessed as total accelerometer counts was not associated with VAT measured with computed tomography. They also did not find a significant association between MVPA and VAT in an analysis where all intensity categories are in cluded in the same model, that is, an analysis similar to ours.…”