title: An estimate of physical activity prevalence in a large population-based cohort.
abstract: OBJECTIVE
  The purpose of this study was to describe the prevalence of self-reported moderate and vigorous physical activity (PA) among 40,261 native Californians in relation to age, gender, education, race/ethnicity, and self-reported disease risk factors.
  
  
  METHODS
  Subjects, from the California Twin Program, completed a questionnaire that included three PA questions and were categorized by their level of PA: moderate and vigorous PA sufficient to meet CDC and ACSM guidelines. The relationship between demographic variables, chronic disease risk factors, and meeting the PA guidelines are reported.
  
  
  RESULTS
  For moderate and vigorous PA, 22.3% and 37.4% of the total group reported meeting the guidelines respectively. Approximately one-half of all subjects met either duration or frequency criteria, but not both, for moderate and vigorous PA. Only 11.2% and 27.4% reported no moderate or vigorous PA, respectively. Significant age and education gradients existed for both moderate and vigorous PA. An inverse association was noted between both moderate and vigorous PA guidelines and prevalence of chronic disease risk factors. Both frequency and duration of PA were required to adequately characterize the association between PA and health outcomes.
  
  
  CONCLUSIONS
  These data demonstrate 1) greater prevalence of sufficient moderate and vigorous PA and lower prevalence of sedentary behavior in this sample compared with adults nationwide, 2) a greater association between vigorous PA and improved health outcomes than was observed for moderate PA, 3) PA guidelines must focus on both frequency and duration of activity, and 4) age and education gradients in moderate and vigorous PA that could have implications for more effective targeting of guidelines to improve the PA prevalence of American adults.
authors.affiliation: Department of Kinesiology and Nutritional Science, California State University-Los Angeles, 5151 State University Drive, Los Angeles, CA 90032-8162, USA. shawkin@calstatela.edu
authors.forename: Steven A
authors.initials: SA
authors.lastname: Hawkins
authors.forename: Myles G
authors.initials: MG
authors.lastname: Cockburn
authors.forename: Ann S
authors.initials: AS
authors.lastname: Hamilton
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Mack
mesh_terms: D000328:Adult; D017677:Age Distribution; D001823:Body Composition; D015992:Body Mass Index; D002140:California / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D015438:Health Behavior; D006801:Humans; D006937:Hypercholesterolemia / Q000453:epidemiology; D006973:Hypertension / Q000453:epidemiology; D008019:Life Style; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D016017:Odds Ratio; D015995:Prevalence; D017678:Sex Distribution; D012959:Socioeconomic Factors; D014427:Twins / Q000706:statistics & numerical data*