"The researchers then cross-referenced sitting time with health outcomes, and found that those people with the “highest sedentary behavior,” meaning those who sat the most, had a 112 percent increase in their relative risk of developing diabetes; a 147 percent increase in their risk for cardiovascular disease; and a 49 percent greater risk of dying prematurely — even if they regularly exercised."
Reducing Occupational Sitting Time and Improving Worker Health: The Take-a-Stand Project, 2011
"Prolonged sitting time (as a specific instance of sedentary behavior), independent of physical activity, has emerged as a risk factor for various negative health outcomes. Study results have demonstrated associations of prolonged sitting time with premature mortality; chronic diseases such as cardiovascular disease, diabetes, and cancer; metabolic syndrome; and obesity. In contrast, breaks in prolonged sitting time have been correlated with beneficial metabolic profiles among adults, suggesting that frequent breaks in sedentary activity may explain lower health risk related to waist circumference, body mass index (BMI), triglyceride levels, and 2-hour plasma glucose levels.
Reductions in sitting time correlated significantly with improved outcomes for upper back and neck pain as well as various mood states."