Health >> Physical Activity >> Physical Activity: Notes & Sources

Physical Activity: Notes & Sources


Confidence interval (also called "error bar") is therange of values that includes the true value 95% of the time. If the confidence intervals of two groups do not overlap, the difference between groups is statistically significant (meaning that chance or random variation is unlikely to explain the difference).   

King County regions: The geographic boundaries of the four King County sub-regions (North, Seattle, East, and South) are defined by the aggregation of ZIP codes.

Physical Activity Guidelines

  • An adult has met the U.S. government’s recommended level of physical activity if he or she reports at least 150 minutes of moderate-intensity physical activity or at least 75 minutes of vigorous-intensity physical activity weekly, plus at least 2 days a week of muscle-strengthening activity. These recommendations were updated in 2008, so direct comparisons with past Communities Count data are invalid. Data on muscle-strengthening activity in adults were not available for 2007 and 2009.
  •  For teens, the government recommends at least 60 minutes of physical activity every day of the week, including muscle-strengthening activities (such as gymnastics) and bone-strengthening activities (such as running).

Race/Ethnicity in adults: Federal standards mandate that race and ethnicity (Hispanic origin) are distinct concepts requiring 2 separate questions when collecting data from an individual. "Hispanic origin" is meant to capture the heritage, nationality group, lineage, or country of birth of an individual (or his/her parents) before arriving in the United States. Persons of Hispanic ethnicity can be of any race. Communities Count's terms for racial/ethnic groups are derived from those used by the U.S Census Bureau in 2010.

  • Communities Count terms:  Hispanic, Non-Hispanic, White Non-Hispanic, Black, American Indian/Alaska Native (AIAN), Asian, Native Hawaiian/Pacific Islander (NHPI), White, and Multiple Race (Multiple). Persons of Hispanic ethnicity can be of any race and are included in other racial categories. Racial/ethnic groups are sometimes combined when sample sizes are too small for valid statistical comparisons of more discrete groups. 
    • 2010 Census terms: Hispanic or Latino, Not Hispanic or Latino, White alone (Not Hispanic or Latino),  Black or African American, American Indian or Alaska Native, Asian, Native Hawaiian or Other Pacific Islander, White, Some Other Race, and Two or More Races.

Race/Ethnicity in teens:  Surveys collecting data on teens do not follow the above convention of asking separate questions about race and ethnicity. Categories are therefore mutually exclusive, so teens are considered White non-Hispanic, Black non-Hispanic, etc.  Teens may also choose multiple races.


Adult data have been averaged over 2 years to enable comparisons across groups that would otherwise be too small for detection of statistically significant results.

National data on teens: Nationally, 18% of youth in grades 9 through 12 did not meet recommended levels of physical activity in 2009. These data are not directly comparable to data on King County teens.

Statistical Significance: Unless otherwise noted, any difference mentioned in the text is statistically significant (unlikely to have occurred by chance).

Data Sources

City Health Profiles provide demographic and health information for 25 geographic areas in King County – mostly large cities (e.g., Seattle, Bellevue), groups of small cities (Bothell/Woodinville), or combinations of cities with nearby unincorporated areas (e.g., Renton/Fairwood). Each report has seven sections:

  • Demographics
  • General health status
  • Leading causes of death
  • Health risk factors and chronic diseases
  • Injury and violence-related mortality
  • Maternal and infant health
  • Access to care and preventive services

Data on adult physical activity come from the Washington State and national Behavioral Risk Factor Surveillance System (BRFSS). The BRFSS is a random telephone interview survey of non-institutionalized adults ages 18 and older that has been conducted in King County every year since 1987. Starting in 2003, the BRFSS was administered in English and Spanish. The question on physical activity level (how long and how many times per week) has been included since 2001 and was asked again in 2003, 2005, 2006, 2007, and 2009. The question on any leisure-time physical activity in the previous month is asked every year. The limitations of an English-and-Spanish-only telephone survey include the following: a) people who do not have a land line telephone or who do not speak English or Spanish are excluded, and b) people who have less education and lower incomes are underrepresented.

Local and state data on teen physical activity come from the 2010 Washington State Healthy Youth Survey. This is a survey of public school students in grades 6, 8, 10, and 12 in which students report on their own physical activity. For additional information on the Healthy Youth Survey, see and

National data on teen physical activity come from the 2009 National Youth Risk Behavior Surveillance System (  Data from local/state and national surveys are not directly comparable due to differences in ages/grades of students surveyed, survey questions, and other methodological differences.

Other Sources

School District Health Profilesprovide demographic and health information for several school districts in King County.  The profiles were developed by Public Health-Seattle and King County in collaboration with school districts for the purpose of informing school policy-makers and administrators, health and wellness planners, and the public about student health indicators at the district level.The data come from the Healthy Youth Survey, which is administered every 2 years to students in grades 6, 8, 10, and 12.  Each profile report has 6 sections: 

  • Demographics of survey respondents
  • Obesity, physical activity, and dietary behaviors
  • Mental health
  • Personal safety and violence
  • Alcohol, tobacco, and other drug use and second-hand smoke exposure
  • 3 additional indicators, selected by each district (examples: adults to turn to for help when feeling sad or hopeless; family skipped meals in past 12 months due to finances; bullied in the past 30 days because of face, ethnicity, or national origin) 

Maps of King County covering a wide range of topics can be accessed at  Maps most immediately relevant to Communities Count are under the headings of Community data & demographics, Public health, and Environment & natural resources, but other maps should be useful as well (farmers markets, transit routes, walking and biking routes, parks, traffic counts, etc.).

Physical activity and  academic performance:

Physical activity guidelines:

  • U.S. Department of Health and Human Services (HHS), Office of Disease Prevention and Health Promotion. 2008 Physical activity guidelines for Americans. Washington: HHS, 2008., accessed 12/07/2012.
  • Adults: Centers for Disease Control and Prevention, How much physical activity do adults need?, accessed 12/06/2012.
  • Children:  Centers for Disease Control and Prevention, How much physical activity do children need?, accessed 12/06/2012.Quotes:  Communities Count interviewed 32 King County parents or guardians raising at least one child younger than 6 years of age.  We reached out to communities of color, recent immigrants, and residents with limited English proficiency to achieve a broad range of racial, cultural, and socioeconomic diversity. We interviewed both families with very low household income and those who earned up to median income (about $68,000 for a family of four in 2010). Family structures included single-parent households, couples living in consensual unions, married couples, and extended families. We also interviewed social service providers from agencies such as Crisis Clinic, Hopelink, Multi-Service Center, and Child Care Resources, as well as staff from community colleges that offer worker retraining or similar programs to help King County residents find jobs. We use fictional names to ensure confidentiality.