Objectives: To provide normative data on maximum oxygen uptake (V O 2 MAX) and physical activity in children 6-7 years of age and analyse the association between these variables. Methods: V O 2 MAX was measured in 366 boys (mean (SD) 6.8 (0.4) years of age) and 332 girls (6.7 (0.4) years of age) from preschool classes in two suburban communities in Copenhagen, during a progressive treadmill exercise. Habitual physical activity was measured with accelerometers. Results: Boys had higher V O 2 MAX both in absolute values (1.19 (0.18) v 1.06 (0.16) litres/min (+11%), p,0.001) and relative to body weight (48.5 (6.0) v 44.8 (5.6) ml/kg/min (+8%); p,0.001) than girls. The difference in V O 2 MAX between boys and girls decreased to +2% when expressed relative to lean body mass (LBM). Absolute V O 2 MAX was related to LBM, body mass, and stature (all p,0.001). Boys were more physically active than girls (mean counts +9.4%, p,0.001), and even when boys and girls with the same V O 2 MAX were compared, boys were more active. The difference in physical activity between the sexes was higher when sustained activity of higher intensity was compared. Conclusions: V O 2 MAX is higher in boys than girls (+11%), even when related to body mass (+8%) and LBM (+2%). Most of the difference in V O 2 MAX relative to body mass was explained by the larger percentage body fat in girls. When boys and girls with the same V O 2 MAX were compared, boys engaged in more minutes of exercise of at least moderate intensity.
Clustering of CVD risk factors developed between the age of six and nine years. At nine years of age clustered CVD risk was highly associated with low fitness level.
Table 3 under the analysis of VO 2peak per LBM contains incorrect data. In the column for multiple R-square (r 2 ), values for multiple R were by mistake inserted. The correct values are listed below.The online version of the original article can be found at http://dx
Previous studies of gender differences in maximum oxygen uptake have come to different conclusions. Limited data exists where the determinants of maximum oxygen uptake have been evaluated in a comprehensive manner. Thus, we examined 248 children (140 boys and 108 girls), aged 7.9-11.1 years. Body composition was determined by dual-energy X-ray absorptiometry, measured variables were total body fat (TBF) and lean body mass (LBM).Maximal oxygen uptake (VO 2PEAK ) was measured by indirect calorimetry during a maximal cycle exercise test. Daily physical activity was assessed by accelerometers and duration of vigorous activity per day (VPA) was calculated. Left ventricular inner diastolic diameter (LVDD) was measured by echocardiography. Lung function was evaluated with spirometric testing and whole body pletysmography. Boys had between 8-18% higher values than girls for VO 2PEAK , dependent upon whether VO 2PEAK was expressed in absolute values or scaled to body mass, lean body mass (LBM) or if allometric scaling was used. In multiple regression analysis absolute values of aerobic fitness were independently related to LBM, maximal heart rate (Max HR), gender, LVDD and VPA. Furthermore, when VO 2PEAK was scaled to body mass it was independently related to ln TBF, Max HR, gender, VPA, and LVDD. Lung function had no relation to VO 2PEAK . Our study concludes that body composition is the main predictor for VO 2PEAK , in children aged 8-11 years, whereas VPA or LVDD has only a modest impact. Existing gender differences in VO 2PEAK cannot be explained only by differences in body composition, physical activity or heart size.
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