Prospectively Reallocating Sedentary Time: Associations with Cardiometabolic Health.

PURPOSE:To investigate whether prospectively reallocating time away from sedentary behaviour into different physical activity intensities is associated with 12-month change to cardiometabolic health in a cohort at high risk of type 2 diabetes (T2DM). METHODS:Participants with known risk factors for T2DM were recruited from primary care (Leicestershire, UK) as part of the Walking Away from Type 2 Diabetes trial (n=808). Participants were followed-up at 12, 24 and 36 months. Sedentary behaviour (SB), light-intensity physical activity (LPA) and moderate-to-vigorous intensity physical activity (MVPA) were measured objectively by accelerometer. Post-challenge glucose, triglycerides, HDL-cholesterol, systolic blood pressure and waist circumference were analysed individually and combined into a clustered cardiometabolic risk score (CMRS). Associations of changing SB over each consecutive 12-month period were analysed taking account of repeated measures.
RESULTS:Reallocating 30 minutes from SB to LPA was associated with 0.21 (95% CI 0.03, 0.38) cm reduction in waist circumference, 0.09 (0.04, 0.13) mmol/l reduction in 2-h glucose, 0.02 (0.00, 0.04) mmol/l reduction in triglycerides and 0.02 (0.01, 0.03) reduction in CMRS. Every 30 minutes reallocation from SB to MVPA was associated with 1.23 (0.68, 1.79) cm reduction in waist circumference, 0.23 (0.10, 0.36) mmol/l reduction in 2-h glucose, 0.04 (0.00, 0.009) reduction in triglycerides and 0.07 (0.04, 0.11) reduction in CMRS. Reallocating 30 minutes from LPA into MVPA was also associated with 1.02 (0.43, 1.60) cm reduction in waist circumference, 0.16 (0.02, 0.30) mmol/l reduction in 2-h glucose and 0.05 (0.01, 0.09) reduction in CMRS.
CONCLUSION:Over 12 months, reallocating time away from SB into LPA or MVPA was associated with improved cardiometabolic health in a population at risk of T2DM, with the greatest benefits observed for MVPA.