1. World Health Organization. Diet and Physical Activity Factsheet. Secondary Diet and Physical Activity Factsheet. 2013. http://www.who.int/dietphysicalactivity/factsheet_inactivity/en/index.html
2. The place of physical activity in the WHO Global Strategy on Diet and physical activity;Bauman;Int J Behav Nutr Phys Act,2005
3. Physical activity guidelines for Americans;U.S. Department of Health and Human Services,2008