title: Secular trends in cardiorespiratory fitness and body mass index in Danish children: The European Youth Heart Study.
abstract: OBJECTIVE
  To examine the secular trends in cardiorespiratory fitness (CF) and body fatness in Danish children. Trends were analyzed overall and across socioeconomic status (SES).
  
  
  METHODS
  Two cross-sectional studies conducted on 589 and 458 third-grade Danish children in 1997-1998 and 2003-2004, respectively. CF was determined by a maximal cycle-ergometer test. The lowest sex-specific quartile of CF in the study from 1997 to 1998 was used as a cut-point for low CF. Body mass index (BMI) cut-points were used to describe overweight, and SES was divided into two groups according to parents' occupation.
  
  
  RESULTS
  This study showed a secular decline in CF in girls overall. Increased CF, BMI, and prevalence of overweight were observed in boys with high SES, in boys with low SES, and in girls with low SES, respectively. However, after additional Bonferroni's correction, none of the statistical analyses performed across socioeconomic gradients reached significant P-values.
  
  
  CONCLUSIONS
  CF declined in girls overall. Although not statistically significant after additional Bonferroni's correction, results in general showed less favorable trends in low SES children. Thus, trying to describe secular trends in CF and body fatness overall without any regard to SES might disguise social-caused differences. However, further studies are needed in order to verify this hypothesis.
authors.affiliation: Institute of Sport Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark. ncmoller@health.sdu.dk
authors.forename: N C
authors.initials: NC
authors.lastname: Møller
authors.forename: N
authors.initials: N
authors.lastname: Wedderkopp
authors.forename: P L
authors.initials: PL
authors.lastname: Kristensen
authors.forename: L B
authors.initials: LB
authors.lastname: Andersen
authors.forename: K
authors.initials: K
authors.lastname: Froberg
mesh_terms: D015992:Body Mass Index; D002318:Cardiovascular Diseases; D002648:Child; D003430:Cross-Sectional Studies; D003718:Denmark; D005060:Europe; D005260:Female; D006801:Humans; D008297:Male; D010809:Physical Fitness / Q000502:physiology*; D018570:Risk Assessment / Q000639:trends; D012923:Social Class