Purpose: We aimed to determine if baseline sedentary behavior was associated with changes in BMI over 9 years.
Methods: Participants were enrolled into the NIH-AARP Diet and Health study in 1995-1996 (median age 63) and BMI was reported at baseline and 9 years later (n=158,436). Sitting time (<3 [referent], 3-4, 5-6, 7-8 or >=9 h/d), television viewing (None, <1, 1-2, 3-4, 5-6, 7-8, or >=9 h/d) and the covariates (age, sex, race, education, smoking, moderate-to-vigorous physical activity, caloric intake, and sleep duration) were reported at baseline. We used longitudinal quantile regression to model changes at the 10th, 25th, 50th, 75th and 90th BMI percentiles.
Results: More sitting at baseline was associated with additional increases in BMI over time and the association was stronger at the upper BMI percentiles (e.g. <3h/d [referent] vs. 5-6 h/d sitting additional increases: 50th percentile = 0.41 kg/m2, 95% CI: 0.34, 0.48 & 90th percentile = 0.85 kg/m2, 95% CI: 0.72, 0.98). Similar associations were observed between more television viewing at baseline and additional increases in BMI over time (e.g., no television [referent] vs. 3-4 h/d of television: 50th percentile= 1.96 kg/m2, 95% CI: 1.77, 2.15 & 90th percentile = 2.11 kg/m2, 95% CI: 1.49, 2.73).
Conclusion: Reducing sedentary behavior could help prevent an increase in BMI in adulthood, especially at the upper percentiles of the BMI distribution, and thereby reduce the prevalence of obesity.
(C) 2014 American College of Sports Medicine