William L. Haskell

Friday, May 18

08:00 – 08:45
The Science of Inactivity and Activity in the Prevention of Chronic Disease

William L. Haskell, PhD

Stanford Prevention Research Center

Stanford University School of Medicine




Presentation Overview

Scientific data continue to accumulate demonstrating that people who are more physically active have a lower chronic disease burden throughout their lifespan than their counterparts who remain sedentary much of the time. Data contributing to the science of inactivity, activity and health come from a wide range of experimental and observational studies that provide the evidence needed to support strong clinical and public health physical activity guidelines.  While the effects of physical activity closely interact with other health behaviors or conditions such as nutrition, mental stress and obesity, physical activity provides independent and unique health benefits.  Most data showing lower chronic disease rates in more active persons come from prospective observational studies. However, numerous well-executed experimental studies have demonstrated the favorable effects of increased activity on a wide range of biomarkers considered to be in the causal pathways between the change in activity and the disease process for major chronic diseases such as coronary heart disease, congestive heart failure, stroke and type-2 diabetes. While strong associations and some experimental data exist linking physical activity to many other chronic conditions such as colon cancer, breast cancer, depression, and dementia, less is understood about potential biological mechanism for these benefits.


Much of the research between the 1950s and 2000 focused on the health benefits and risks of moderate- or vigorous-intensity physical activity (MVPA), but recently a major research emphasis has been on the health risks associated with sedentary behavior, primarily sustained sitting. Preliminary data indicate that reducing sitting time and inserting “breaks” throughout the day may provide health benefits independent of MVPA.

Based on extensive systematic reviews of the scientific literature physical activity guidelines have published by a number of developed countries (e.g., USA, Canada, UK, Brazil) and for developing countries by the World Health Organization with excellent harmonization across guidelines.



William L. Haskell, Ph.D. is Professor of Medicine (active emeritus) in the Stanford Prevention Research Center and the Division of Cardiovascular Medicine at Stanford University. He has been a member of the Stanford Medical School faculty for the past 38 years with primary interests in applied and clinical research in preventive cardiology, cardiac rehabilitation, physical activity and chronic disease and successful aging. He has served on numerous national and international panels responsible for developing guidelines for physical activity and public health, preventive cardiology and cardiac rehabilitation. He was chair of the Physical Activity Guidelines Advisory Committee for DHHS in 2008. During 2008-2010, he was a scientific advisor to the World Health Organization for the development of WHO Global Recommendations on Physical Activity for Health (2010) and to the United Kingdom Health Ministries for the development of United Kingdom Physical Activity and Sedentary Behavior Guidelines (2011). Currently, he is Chair of the International Review Panel for the Evaluation of Exercise and Sports Sciences in the Nordic Countries.