United States Department of Health and Human Services
2008 Physical Activity Guidelines for Americans
http://www.health.gov/paguidelines/guidelines/default.aspx#toc

5210 Lets Go Campaign
www.letsgo.org

Centers for Disease Control and Prevention
http://www.cdc.gov/physicalactivity/everyone/guidelines/children.html

National Institutes of Health – Osteoporosis and Related Bone Disease National Resource Center
Kids and Their Bones: A Guide for Parents
http://www.niams.nih.gov/Health_Info/Bone/Bone_Health/Juvenile/default.asp