title: Maternal inactivity: 45-year trends in mothers' use of time.
abstract: OBJECTIVE
  To examine 45-year trends in time use and physical activity energy expenditure (PAEE) in a nationally representative sample of US mothers.
  
  
  METHODS
  We quantified time allocation to physical activity (PA), sedentary behaviors (SED), and PAEE from 1965 to 2010 in mothers with older children (MOC) (>5 to ≤18 years) and mothers with younger children (MYC) (≤5 years). Physical activity was the sum of time allocated to housework, child care, laundry, food preparation, postmeal cleanup, and exercise. Sedentary behavior was the sum of time spent in a vehicle and using screen-based media. Physical activity energy expenditure was calculated using body weights from national surveys and metabolic equivalents.
  
  
  RESULTS
  From 1965 to 2010, the time allocated to PA decreased by 11.1 h/wk (from 32.0 to 20.9 h/wk) in MOC and by 13.9 h/wk (from 43.6 to 29.7 h/wk) in MYC. The time spent in SED increased by 7.0 h/wk in MOC (from 17.7 to 24.7 h/wk) and increased by 5.7 h/wk in MYC (from 17.0 to 22.7 h/wk). Physical activity energy expenditure decreased by 1237.6 kcal/wk (176.8 kcal/d) in MOC (from 5835.3 to 4597.7 kcal/wk), and in MYC, PAEE decreased by 1572.5 kcal/wk (224.6 kcal/d), from 7690.5 to 6118.0 kcal/wk.
  
  
  CONCLUSIONS
  There was a significant reallocation of time by mothers from PA (eg, housework) to SED (eg, watching television) between 1965 and 2010. Given the essential role of PA for health and the potential for the intergenerational transmission of obesity and obesogenic behaviors, these results suggest that maternal inactivity may be an important target for the primary prevention of chronic noncommunicable diseases and obesity.
authors.affiliation: Department of Exercise Science, Arnold School of Public Health, University of South Carolina, Columbia. Electronic address: archerec@email.sc.edu.
authors.forename: Edward
authors.initials: E
authors.lastname: Archer
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Lavie
authors.forename: Samantha M
authors.initials: SM
authors.lastname: McDonald
authors.forename: Diana M
authors.initials: DM
authors.lastname: Thomas
authors.forename: James R
authors.initials: JR
authors.lastname: Hébert
authors.forename: Sharon E
authors.initials: SE
authors.lastname: Taverno Ross
authors.forename: Kerry L
authors.initials: KL
authors.lastname: McIver
authors.forename: Robert M
authors.initials: RM
authors.lastname: Malina
authors.forename: Steven N
authors.initials: SN
authors.lastname: Blair
mesh_terms: D000328:Adult; D015992:Body Mass Index; D015986:Confounding Factors, Epidemiologic; D004734:Energy Metabolism; D015444:Exercise; D005260:Female; D006291:Health Policy / Q000639:trends; D006801:Humans; D008875:Middle Aged; D009035:Mothers / Q000706:statistics & numerical data*; D009043:Motor Activity; D009765:Obesity / Q000209:etiology / Q000517:prevention & control; D011634:Public Health / Q000639:trends; D012494:Sampling Studies; D057185:Sedentary Behavior; D011795:Surveys and Questionnaires; D013690:Television / Q000706:statistics & numerical data; D014481:United States / Q000453:epidemiology
keywords: AHTUS; American Heritage Time Use Study; CVD; FAO/WHO/UNU; Food and Agriculture Organization of the United Nations, World Health Organization, and United Nations University; MET; MOC; MYC; NCD; PA; PA energy expenditure; PA-h/wk; PAEE; SED; SED-h/wk; TV; cardiovascular disease; hours of PA per week; hours of SED per week; metabolic equivalent tasks; mothers with older children; mothers with younger children; noncommunicable disease; physical activity; sedentary behaviors; television