Keith Diaz, PhD is a certified exercise physiologist and Assistant Professor of Behavioral Medicine at Columbia University Medical Center. He is Director of the Exercise Testing Laboratory at the Center for Behavioral Cardiovascular Health. He conducts laboratory- and observational-based research to elucidate the role of prolonged sedentary behavior in the pathogenesis of cardiovascular disease, with a specific focus of iteratively optimizing feasible, sustainable, and cost-effective guidelines for reducing prolonged sitting. He is currently PI of a prospective cohort study examining objectively-measured sedentary behavior as a risk factor for recurrent cardiovascular outcomes in coronary heart disease patients. He is also PI of laboratory-based, cross-over trial examining the optimal frequency and duration of sedentary breaks for improving cardiometabolic health.