ABSTRACT
Introduction ............................................................................................................ 196 Background ............................................................................................................ 196 Development of 2008 Physical Activity Guidelines .............................................. 198 Overview of 2008 Physical Activity Guidelines for Americans ............................. 198
Dose-Response Relationships .......................................................................... 199 Combining Moderate-and Vigorous-Intensity Activity ....................................200 Frequency of Aerobic Activity ..........................................................................200 Absolute versus Relative Intensity ....................................................................200 Muscle-Strengthening Activities ....................................................................... 201 Balance Training ............................................................................................... 201 Flexibility Activities .......................................................................................... 201 Medical Consultation ........................................................................................ 201 Healthy Weight ..................................................................................................202 Physical Activity for Children and Adolescents ................................................202 Physical Activity for Women during Pregnancy and the Postpartum Period ......... 202 Physical Activity for People with Chronic Conditions and Disabilities ...........202 Adverse Events and Safety ................................................................................203
Challenges of Communicating Physical Activity Guidelines ................................204 Appropriately Targeting the Intended Audience ...............................................204 Clarifying Target Amounts of Activity ..............................................................204 De—ning Levels of Intensity ..............................................................................205 Supporting Dissemination and Maintaining Public Awareness ........................205
Moving forward with Guidelines When Evidence Is Incomplete ..........................205 Role of Physical Activity Guidelines in Improving Health ...................................206 Conclusion .............................................................................................................207 Study Questions .....................................................................................................208 References ..............................................................................................................208
The U.S. Department of Health and Human Services (HHS) announced and released the 2008 Physical Activity Guidelines for Americans (U.S. Department of Health and Human Services 2008) in October of that year, the —rst time that the Federal government had published comprehensive physical activity guidelines. The Guidelines development process began with a systematic review of epidemiologic literature and the resulting document extended earlier government recommendations and professional organization position statements. Since their release, the Physical Activity Guidelines have been widely disseminated and used in many ways. Other countries, including Canada, the United Kingdom, Ireland, Austria, and Finland, have used the Physical Activity Guidelines Advisory Committee Report, 2008 and the 2008 Physical Activity Guidelines for Americans to develop their national guidelines or recommendations. The documents produced by other nations present the same or very similar recommendations. The World Health Organization (2010) has also adapted the 2008 Guidelines for use in its member countries.
