Dose-Response Issues and Challenges in Physical Activity Research

The American College of Sports Medicine and the American Medical Association launched “Exercise is Medicine™” in 2007 to encourage Americans to incorporate physical activity (PA) and exercise into their daily routine and calls on doctors to prescribe exercise to their patients. Because exercise is medicine, the question “How much” (How much exercise is needed to be able to receive health and medical benefits?) will naturally be asked. To fully answer this question, the relations between the dose and response must be understood. The human body is an organism, which is able to make both adaptive physiological and psychological responses to various stimuli. In 1994, William Haskell provided a nice theoretical framework for dose-response related research in PA and health. In 2000, a symposium on “dose-response” was organized and a special issue on this topic was published in a Medicine & Science in Sports & Exercise supplement (June, 2001). Yet, many critical questions such as “What is the best way to measure dose? Focus on energy expenditure or PA movement itself?” “What is the best outcome to define response? “Which mode (a combinations of a set of exercises or PA) works best?” “What is the ideal interval between exercise interventions?” etc. have not been answered. The dose-response research field also has not taken advantage of the latest theories and methods in research design, measurement and statistics. After providing an overview on dose-response in PA and health, this presentation will address in depth critical issues in dose-response research.