title: Validity of questionnaire-based assessment of sedentary behaviour and physical activity in a population-based cohort of older men; comparisons with objectively measured physical activity data.
abstract: BACKGROUND
  Older adults are the most inactive age group and self-reporting of activities may be complicated by age-related reductions in structured activities and misclassification or recall biases. We investigate the validity of simple questionnaires about sedentary behaviour (SB), (including the widely used proxy television (TV) viewing), and physical activity (PA) in comparison with objective measures.
  
  
  METHODS
  Community dwelling men aged 71-93 years, from a UK population-based cohort wore a GT3X accelerometer over the right hip for 7 days and self-completed a questionnaire including information about SB (TV, reading, computer use and car use) and PA (leisure and sporting domains).
  
  
  RESULTS
  1566/3137 surviving men (mean age 79 years) attended. 1377 ambulatory men provided questionnaire and accelerometer data. Questionnaires under-estimated mean daily sedentary time; 317 minutes total SB (TV, computer use, reading or driving), 176 minutes (TV) vs 619 minutes (objectively measured). Correlations between objective measures and self-reports were 0.18 (total SB) and 0.17 (TV), both P < 0.001. Objective SB levels were similar across the lowest three quartiles of self-reported SB but raised in the highest quartile. Correlations between steps/day or moderate to vigorous PA with self-reported total PA were both 0.49, P < 0.001 and measured PA levels were progressively higher at higher levels of self-reported PA.
  
  
  CONCLUSIONS
  Among older men, simple SB questions performed poorly for identifying total SB time, although simple PA questions were associated with a graded increase with objectively measured PA. Future studies of health effects of SB in older men would benefit from objective measures of SB.
authors: UCL Department of Primary Care & Population Health, UCL Medical School, Rowland Hill Street, London, NW3 2PF, UK. b.jefferis@ucl.ac.uk.|UCL Physical Activity Research Group, University College London, London, UK. b.jefferis@ucl.ac.uk.
authors: Barbara J
authors: BJ
authors: Jefferis
authors: UCL Department of Primary Care & Population Health, UCL Medical School, Rowland Hill Street, London, NW3 2PF, UK.|UCL Physical Activity Research Group, University College London, London, UK.
authors: Claudio
authors: C
authors: Sartini
authors: UCL Department of Primary Care & Population Health, UCL Medical School, Rowland Hill Street, London, NW3 2PF, UK.
authors: Sarah
authors: S
authors: Ash
authors: UCL Department of Primary Care & Population Health, UCL Medical School, Rowland Hill Street, London, NW3 2PF, UK.
authors: Lucy T
authors: LT
authors: Lennon
authors: UCL Department of Primary Care & Population Health, UCL Medical School, Rowland Hill Street, London, NW3 2PF, UK.
authors: S Goya
authors: SG
authors: Wannamethee
authors: Population Health Research Institute, St George's University of London, Cranmer Terrace, London, SW17 0RE, UK.
authors: Peter H
authors: PH
authors: Whincup
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001334:Automobile Driving; D015331:Cohort Studies; D003201:Computers; D015444:Exercise; D015438:Health Behavior; D006801:Humans; D007899:Leisure Activities; D008297:Male; D009043:Motor Activity; D057185:Sedentary Behavior; D057566:Self Report; D013177:Sports; D011795:Surveys and Questionnaires / Q000592:standards*; D013690:Television