Cardiorespiratory fitness and physical activity level in adolescents

Abstract

More objective methods to detect inactive adolescents may help identify young people that are vulnerable to obesity and other chronic diseases. The objective of this study was to examine the association between classifications obtained with the cardiorespiratory fitness test and physical activity level in adolescents, as well as the agreement between tertiles and z-score distribution of the variables generated with these methods (distance covered and total physical activity score). A cross-sectional study was conducted using a random sample of 639 adolescents (61% girls) aged 12 to 19 years (mean age of 16 ± 1.8 and categorized into two age groups: 12-13 and 14-19 years), from public schools in Niterói, Rio de Janeiro, Brazil. Cardiorespiratory fitness was assessed by a 9-min run/walk test (T9) and physical activity level by the International Physical Activity Questionnaire (IPAQ). The chi-square test (or Fisher’s exact test) and Kruskal-Wallis test were applied for the evaluation of associations, and the weighted kappa coefficient and intraclass correlation coefficient were used to investigate agreement between variables. A level of significance of p<0.05 was adopted. A significant association between the classifications obtained with the two methods was only observed for adolescents aged ≥ 14 years. However, there was agreement between the variables generated with the two methods in both age groups. The median distance covered in the T9 increased according to tertiles of total physical activity score. An association between the classifications obtained with the IPAQ and T9 was only found for older adolescents. However, the continuous variables and variables categorized into tertiles generated with the methods were associated and showed agreement in both age groups.