Objectively-measured sedentary time and cardiometabolic health in adults with severe obesity

It is unknown whether sedentary behavior is independently associated with the cardiometabolic health of adults with severe obesity. Additionally, there is debate regarding how best to derive meaningful indices of sedentary time (ST) from activity monitor data. A convenience sample of adults with severe obesity (N=927; 79% female, median age 45 y, median body mass index (BMI) 46 kg/m²) completed a research assessment at one of ten US hospitals in 2006-2009 prior to bariatric surgery. Cardiometabolic health was assessed via physical measures, fasting blood samples and medication use. Indices of ST were derived from StepWatch™ activity monitor data with minimum bout durations of 1 min, 10 min and 30 min. Cross-sectional associations were examined. Median (25th, 75th percentile) ST was 9.3 h/d (8.1, 10.5) in ≥1 min bouts, 6.5 h/d (5.2, 8.0) in ≥10min bouts, or 3.2 h/d (2.1, 4.5) in ≥30 min bouts. Associations with ST were generally strongest with the ≥10 min bout duration. Independent of moderate-to-vigorous intensity physical activity, BMI and other potential confounders, 1h/day ST in ≥10min bouts was associated with higher odds of diabetes by 15% (95%CI: 1.05-1.26), metabolic syndrome by 12% (95%CI: 1.01-1.24) and elevated blood pressure by 14% (95%CI: 1.02-1.26), and was associated with 1.4 cm (95%CI: 0.9-1.9) larger waist circumference. Findings indicate the importance of considering ST as a distinct health risk among adults with severe obesity, and suggest a 10 min minimum duration may be preferable to 1 min or 30 min for establishing ST from activity monitor data.