Corresponding author Glenn A. Gaesser, PhD Kinesiology Program, University of Virginia, 210 Emmet Street So., PO Box 400407, Charlottesville, VA 22904, USA. E-mail: Gag2q@virginia.edu Current Diabetes Reports 2007, 7: 14–19 Current Medicine Group LLC ISSN 1534-4827 Copyright © 2007 by Current Medicine Group LLC A considerable number of observational and interven- tion studies support the role of exercise as a cornerstone in prevention and treatment of cardiovascular disease (CVD), type 2 diabetes (T2D), and the metabolic syn- drome. Physical activity and cardiorespiratory fitness are also associated with reduced mortality rates among persons with CVD, T2D, and metabolic syndrome. Exercise has definite acute effects on a number of risk markers for CVD and T2D, in addition to more sub- stantial benefits with chronic training. Both aerobic and resistance exercise have therapeutic value, largely independent of weight loss, and should be included in exercise programs. Introduction Exercise, either alone or in combination with comprehen- sive lifestyle intervention, is considered a cornerstone in the prevention and management of diabetes, cardiovascu- lar disease (CVD), and metabolic syndrome. Poor physical itness is a signi icant predictor of risk for developing type 2 diabetes (T2D), CVD, and the metabolic syndrome [1,2••,3••]. Among persons with and without diabetes, low cardiorespiratory itness (CRF) [4] and low physical activity levels [5] have been reported to be signi icant predictors of all-cause and cardiovascular mortality. CRF and muscular strength are also important predictors of the metabolic syndrome [1,6]. Among adolescents, data from the National Health and Nutrition Examination Survey 1999 to 2002 revealed that physical activity and CRF were positively associated with insulin sensitivity [7]. Thus, there is compelling evidence to suggest that physical activity, particularly exercise suf icient to improve CRF and muscle strength, should be encouraged to both prevent and manage diabetes, reduce prevalence of the metabolic syndrome, and reduce morbidity and mortality associated with diabetes and metabolic syndrome. Only 11% to 46% (depending on age and sex) of US adults engage in regular leisure-time physical activity, deined as light-to-moderate activity ive times or more per week for 30 minutes each time, or vigorous activity three or more times per week for 20 minutes or more each time [3••]. Exercise rates among those with diabetes are likely even lower than the general population. Although health care professionals appear to be encouraging those with or at highest risk for diabetes to exercise, data from the Medical Expenditure Panel Survey indicate that less than one half of persons with at least three risk factors for diabetes reported ever receiving advice from a health professional to exercise [8]. This suggests missed opportu- nities for prevention of diabetes and CVD, and treatment of risk factors associated with diabetes and CVD. Thus, there is a need to increase awareness of the beneits of physical activity and to develop strategies to increase physical activity levels and itness capacity of persons with or at risk for diabetes or the metabolic syndrome. Epidemiologic Evidence It is well established that physical activity is an effective behavior for reducing risk of many chronic diseases, such as CVD and T2D [1,2••,3••,4,5]. A number of cohort studies have demonstrated consistent inverse associa- tions between physical activity and/or physical itness and incidence of T2D, CVD, and/or the metabolic syndrome [1,2••,3••,4,5]. Physical activity Both moderate- and vigorous-intensity physical activity appear to be effective [2••,3••]. In the Nurses’ Health Exercise for Prevention and Treatment of Cardiovascular Disease, Type 2 Diabetes, and Metabolic Syndrome Glenn A. Gaesser, PhD