In adults, the total amount of time spent sitting affects heart health and risk of diabetes regardless of how physically active people are. In addition, extended periods of sitting are especially harmful to health. Our recent studies have shown large increases in sitting throughout childhood and adolescence and most teenagers will spend almost 9h/day sitting by the time they reach age 15y, that is more than the average American adult sits. This has led to an increasing interest in policy and research interventions aiming to reduce sitting in children and teenagers. However, there is limited evidence on whether sitting time matters to health in the teenage years. To inform future research and policy interventions which aim to change sitting behaviour it is crucial to establish whether or not it actually affects health during the teenage years. This project will, making use of ALSPAC data, test whether changes in sitting behaviour between ages 12y and 16y affect risk factors for heart disease and diabetes. The study will confirm whether or not sitting affects health in the teenage years. The results of this project will provide important information about
a. whether or not sitting behaviour should be targeted by future efforts to prevent heart disease, stroke, diabetes, and obesity and
b. will help future researchers to design innovative evidence based intervention studies targeting sitting behaviour in the teenage years.