Breaking up Prolonged Sedentary Behavior to Improve Cardiometabolic Health

For the sedentary break (walking) condition, participants will be randomized to 1 of 25 combinations of frequency (5 doses: sedentary break every 30, 45, 60, 90, or 120 minutes) and duration (5 doses: sedentary break duration of 1, 3, 5, 7, or 10 minutes). Participants will complete a 9-hour study visit and will remain seated throughout the lab visit and will take regular sedentary breaks by walking on a treadmill at 2.0 mph and 0% incline at specific frequency and duration (as determined by the randomization method) for the entirety of the visit.

While completing the sitting (control) condition, participants will complete the 9-hour study visit by remaining seated and only standing up/walking to use the restroom at specified times.

Participants in both the experimental and control groups will eat a controlled diet (breakfast, lunch, dinner, snacks) for two full days before each lab visit. They will also eat a controlled diet (breakfast, lunch) during each of the two lab visits. Participants will choose 1 of 3 dietary menus to eat for the study duration. Each meal will be individualized to meet 33% of daily estimated energy requirements. Target macronutrient profile will be 12-15% energy from protein, 55-58% from carbohydrate and 29-31% from fat; as well as 55 mmol of sodium and 24 mmol of potassium.