Abstract P317: Bidirectional Associations Between Accelerometer-Measured Sedentary Time, Physical Activity, and Weight Over 10 Years in the CARDIA Study

Abstract

Introduction: Though a pattern of high sedentary time (ST) with low light-intensity (LPA) and moderate-to-vigorous intensity PA (MVPA) is associated with weight gain, other data suggest excess weight may precede this behavioral profile in the causal pathway. Objective: To investigate bidirectional associations between activity patterns and weight over 10 years. Methods: Analysis included 886 CARDIA participants (aged 38-50 years, 62% female, 38% black) with weight and accelerometry (≥4 d with ≥10 hr/d) at the year 20 (ActiGraph 7164; 2005-6) and year 30 (ActiGraph wGT3X-BT; 2015-6) exams. Accelerometer data were harmonized and expressed as counts per minute (cpm) and time-dependent (min/d) intensity categories (ST, LPA, MVPA). Linear regression models were constructed to estimate adjusted associations of baseline (Y20) activity with 10-y change in weight and vice versa. Model 2 further adjusted for concurrent 10-y change in the independent variable. When intensity categories were the independent variables, regression coefficients estimated the effect of replacing ST with LPA or MVPA, adjusted for accelerometer wear time. Results: Over the 10-y follow-up, weight increased by a mean 2.55 ± 8.05 kg; mean total activity (cpm) decreased by -50 ± 153 cpm. Higher baseline cpm and MVPA were associated with a reduced 10-y weight gain (Model 1); further adjustment for concurrent changes in activity (Model 2) strengthened associations such that both baseline LPA and MVPA were each related to reduced 10-y weight gain ( Table ). Conversely, higher baseline weight was associated with unfavorable changes in activity profile such that ST increased and cpm, LPA, and MVPA decreased over the 10-y follow-up (Model 1); results were similar after adjustment for concurrent weight change (Model 2; Table ). Conclusions: Poor activity profiles and body weight were bidirectionally related. Interventions that work simultaneously to replace ST with LPA and MVPA while also using other methods to address excess weight may be optimal.