title: Trend and prevalence estimates based on the 2008 Physical Activity Guidelines for Americans.
abstract: BACKGROUND
  According to the 2008 Physical Activity Guidelines for Americans, adults need to engage in at least 150 minutes/week of moderate-intensity activity or its equivalent (defined as aerobically active) to obtain substantial health benefits and more than 300 minutes/week (defined as highly active) to obtain more extensive health benefits. In addition to aerobic activity, the 2008 Guidelines recommend that adults participate in muscle-strengthening activities on 2 or more days/week.
  
  
  OBJECTIVE
  This study examined the prevalence and trends of meeting the activity criteria defined by the 2008 Guidelines among U.S. adults.
  
  
  METHODS
  Prevalence and trends of participation in leisure-time physical activity were estimated from the 1998-2008 National Health Interview Survey (analyzed in 2010).
  
  
  RESULTS
  In 2008, 43.5% of U.S. adults were aerobically active, 28.4% were highly active, 21.9% met the muscle-strengthening guideline, and 18.2% both met the muscle-strengthening guideline and were aerobically active. The likelihood of meeting each of these four activity criteria was similar and were associated with being male, being younger, being non-Hispanic white, having higher levels of education, and having a lower BMI. Trends over time were also similar for each part of the 2008 Guidelines, with the prevalence of participation exhibiting a small but significant increase when comparing 1998 to 2008 (difference ranging from 2.4 to 4.2 percentage points).
  
  
  CONCLUSIONS
  Little progress has been made during the past 10 years in increasing physical activity levels in the U.S. There is much room for improvement in achieving recommended levels of physical activity among Americans, particularly among relatively inactive subgroups.
authors.affiliation: National Center for Chronic Disease Prevention and Health Promotion, CDC, Atlanta, Georgia 30341, USA. clo3@cdc.gov
authors.forename: Susan A
authors.initials: SA
authors.lastname: Carlson
authors.forename: Janet E
authors.initials: JE
authors.lastname: Fulton
authors.forename: Charlotte A
authors.initials: CA
authors.lastname: Schoenborn
authors.forename: Fleetwood
authors.initials: F
authors.lastname: Loustalot
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D004522:Educational Status; D015444:Exercise; D005260:Female; D019983:Guideline Adherence / Q000639:trends; D017408:Guidelines as Topic; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D053580:Muscle Strength / Q000502:physiology*; D015995:Prevalence; D012737:Sex Factors; D014481:United States; D055815:Young Adult