title: Self-reported physical activity compared with maximal oxygen uptake in adults.
abstract: BACKGROUND
  Physical activity level and cardiorespiratory fitness are both inversely associated with the risk of cardiovascular diseases and with all-cause mortality. Physical activity questionnaires are often validated against objectively measured maximal oxygen uptake (VO2max).
  
  
  OBJECTIVE
  To validate a self-report physical activity questionnaire against VO2max and furthermore to establish whether a simple question on self-rated physical fitness could predict objectively measured VO2max.
  
  
  METHODS
  A total of 102 men and women aged between 35 and 65 years were recruited from an ongoing population-based intervention study, the Inter99 Study. Participants reported their self-rated fitness and daily physical activity using a new questionnaire based on metabolic equivalents (MET). VO2max (ml/kg per min) was determined using a graded bicycle test with increasing workload until exhaustion and with simultaneous measurement of breath-to-breath oxygen uptake in 15-s periods. Statistical analyses were performed by linear regression analyses using the self-reported physical activity level as an independent variable and VO2max (l/min) as an dependent variable, and with covariates sex, age and bodyweight.
  
  
  RESULTS
  Data from 53 men and 47 women were analysed. The amount of daily vigorous activity (>6 MET) was significantly positively associated with VO2max (P=0.0001, R=0.76), whereas the total amount of physical activity was not significantly associated with VO2max (P=0.098, R=0.69). A significant trend across three groups of self-rated fitness in relation to VO2max (ml/kg per min) was found (P for trend <0.0001).
  
  
  CONCLUSIONS
  The physical activity questionnaire has acceptable validity when compared with VO2max in adult men and women. Furthermore, a simple question on self-rated fitness seems to reflect measured VO2max objectively.
authors.affiliation: Research Centre for Prevention and Health, Glostrup University Hospital, Glostrup, Denmark. metaad01@glostruphosp.kbhamt.dk
authors.forename: Mette
authors.initials: M
authors.lastname: Aadahl
authors.forename: Michael
authors.initials: M
authors.lastname: Kjaer
authors.forename: Jens H
authors.initials: JH
authors.lastname: Kristensen
authors.forename: Birgit
authors.initials: B
authors.lastname: Mollerup
authors.forename: Torben
authors.initials: T
authors.lastname: Jørgensen
mesh_terms: D000328:Adult; D015444:Exercise; D005080:Exercise Test; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism*; D009203:Myocardial Infarction / Q000209:etiology* / Q000378:metabolism / Q000503:physiopathology; D010101:Oxygen Consumption; D010809:Physical Fitness; D015203:Reproducibility of Results; D018570:Risk Assessment; D011795:Surveys and Questionnaires