Sedentary Behavior Interrupted Randomized Controlled Trial (P2)

Primary Aims: In our primary biomarker outcomes of glucose regulation (fasting insulin \& glucose, HbA1c, HOMA-IR) \& blood pressure (BP): 1. Investigate the 12 week effects of increased standing and additional brief sit-to-stand compared to attention controls. 2. Investigate the dose-response effects of behavioral change on the biomarkers \& BP. Secondary aims 1. Assess the effect of changes in standing and sit-to-stand transitions at 12 weeks on physical, emotional \& cognitive functioning. 2. Assess the effect of changes in standing and sit-to-stand transitions at 12 weeks on in vivo skeletal muscle mitochondrial function. Exploratory aims 1. Explore the possible modifying effect of age on the relationship between intervention conditions \& primary \& secondary outcomes. 2. Explore the psychosocial \& environmental mediators \& moderators of changes in sitting time, standing time, and transitions. 3. Explore differences in outcomes between the 2 sitting interruption conditions.