title: Cardiovascular fitness is associated with bias between self-reported and objectively measured physical activity.
abstract: The aim of this research study was to determine whether the level of agreement between self-reported and objective measures of physical activity (PA) is influenced by cardiovascular fitness. Participants (n = 113) completed the Global Physical Activity Questionnaire (GPAQ), a health risk assessment and a sub-maximal 12-minute step test. Age-predicted VO2max was used to classify participants as lower fit and higher fit (HF). ActiGraph (GT3X) accelerometers were worn for 7 consecutive days. Matthews cut points were used to calculate minutes of moderate and vigorous PA (MVPA) per week. Bland-Altman plots were used to measure limits of agreement between GPAQ and ActiGraph MVPA. The participants' mean age was 37.9 ± 12.7 years and more than 60% were categorised as HF (n = 71). Moderate PA was over-reported in 39% of all participants. Most of the over-reporters for moderate PA were in the HF group (64.1%). Vigorous PA was over-reported by 72.6% of all participants. The discrepancy between self-reported and objective measures of vigorous PA increased with increasing self-reported time spent in vigorous PA. Fitter individuals appear to over-report PA more than lesser fit participants, suggesting that fitness could influence the level of agreement between self-reported and objective measures of PA.
authors.affiliation: a Department of Human Biology, Faculty of Health Sciences , MRC/UCT Research Unit for Exercise Science and Sports Medicine, University of Cape Town , Cape Town , South Africa.
authors.forename: S A
authors.initials: SA
authors.lastname: Tomaz
authors.affiliation: a Department of Human Biology, Faculty of Health Sciences , MRC/UCT Research Unit for Exercise Science and Sports Medicine, University of Cape Town , Cape Town , South Africa.
authors.forename: E V
authors.initials: EV
authors.lastname: Lambert
authors.affiliation: a Department of Human Biology, Faculty of Health Sciences , MRC/UCT Research Unit for Exercise Science and Sports Medicine, University of Cape Town , Cape Town , South Africa.
authors.forename: D
authors.initials: D
authors.lastname: Karpul
authors.affiliation: a Department of Human Biology, Faculty of Health Sciences , MRC/UCT Research Unit for Exercise Science and Sports Medicine, University of Cape Town , Cape Town , South Africa.|b Centre for Research on Exercise, Physical Activity and Health, School of Human Movement Studies , University of Queensland , Brisbane , QLD , Australia.
authors.forename: T L
authors.initials: TL
authors.lastname: Kolbe-Alexander
mesh_terms: D061725:Accelerometry; D056044:Actigraphy; D000328:Adult; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010809:Physical Fitness / Q000502:physiology*; D057566:Self Report; D011795:Surveys and Questionnaires
keywords: Accelerometer; ActiGraph GT3X; GPAQ; physical activity