ered in their level of physical fitness (i.e., fit and unfit) in a manner that wassimilar to that of the first analysis. The same models were used to examine the contribution of theduration of time that participants spent on MVPA during PE class (PE-MVPA) to daily activity; the ratioof PE-MVPA to daily MVPA were the dependent variables. All analyses were adjusted for age, BMI,and CRF z-scores. The Cochran’s Q test was conducted to compare the percentages of participantswho achieved the recommended duration of daily MVPA (i.e., 60 minutes) on days with and withoutPE classes; subsequently, post-hoc analysis, namely, McNemar’s test, was performed to examine thesignificant results of the Cochran’s Q test. All analyses were conducted using version 24 of IBM SPSS(IBM, Armonk, NY), and the statistical significance of the results was tested at an alpha level of 0.05.3. ResultsThe descriptive statistics for the study variables, which were computed using data that wereobtained from the 111 schoolchildren (75% inactive and 73% unfit) who met our inclusion criteria,are shown in Table1. Active and inactive schoolchildren did not significantly differ on anthropometricmeasures or in PE-MVPA. However, when compared to inactive schoolchildren, active schoolchildrenspent more time on daily MVPA (M1-M2=33.4, 95% CI=26.4, 40.3), obtained a higher CRF z-score(M1-M2=0.4, 95% CI=0.2, 0.6), and were faster during the 20 m shuttle run (M1-M2=0.5, 95% CI=0.2, 0.7). Similarly, as can be seen in Table1, fit schoolchildren were younger (M1-M2=-0.6, 95%CI=-1.0,-0.3), had a lower body weight (M1-M2=-5.8, 95% CI=-10.8,-0.9) and BMI (M1-M2=-2.0, 98% CI=-3.1,-0.9), and a higher mean CRF z-score (M1-M2=0.7, 98% CI=0.6, 0.9) thanunfit schoolchildren. Fit and unfit groups did not differ in PE-MVPA and daily MVPA.

Int. J. Environ. Res. Public Health2019,16, 23975 of 12Table 1.Descriptive statistics for the study variables across groups that differed in their levels ofphysical activity and fitness.VariableMean (SD)Activity StatusFitness StatusTotal SampleActiveInactiveFitUnfitn=111n=27n=84n=29n=82Age (years)13.6 (0.8)13.7 (0.9)13.6 (0.7)13.1 (0.7)†13.8 (0.8)Height (cm)154 (10)153 (10)155 (10)154 (11)155 (10)Weight (kg)46.8 (11.8)44.5 (11.3)47.5 (11.9)42.4 (9.1)†48.3 (12.3)BMI (kg/m2)19.3 (3.3)18.8 (2.7)19.5 (3.4)17.8 (2.3)†19.8 (3.4)BMI (z-score)0.2 (1.5)-0.2 (1.3)0.2 (1.6)-0.3 (1.1)†0.4 (1.6)20 m SRT (speed)9.7 (0.6)10.1 (0.6) *9.5 (0.62)10.3 (0.4)†9.5 (0.6)20 m SRT (z-score)-1.2 (0.5)-0.9 (0.4) *-1.3 (0.5)-0.6 (0.2)†-1.4 (0.4)VO2 peak (mL/kg/min)38.5 (0.5)40.5 (2.6) *37.8 (3.5)42.5 (1.4)†37.1 (2.9)Daily MVPA (min)50.6 (25.5)75.9 (22.4) *42.5 (21.3)56.8 (21.6)48.4 (21.0)PE-MVPA (min)9.9 (3.6)10.8 (4.0)9.7 (3.4)10.3 (3.9)9.8 (3.4)PE-MVPA (%)22.1 (7.9)23.9 (9.1)21.5 (7.5)22.9 (8.6)21.8 (7.7)Note. * The mean is significantly different from that of the inactive group (p<0.05).†The mean is significantlydifferent from that of the unfit group (p<0.05).3.1. Physical Activity on Days with and without PE ClassesThe estimated marginal means for time spent on MVPA are shown in Figures1and2; across thethree multilevel analyses, the effects of school clusters (random effect), and age and BMI (fixed effects)were adjusted. In general, schoolchildren spent more time on MVPA (M1-M2=12.9, 95% CI=7.1,18.6) on PEday+than on Day no-PE. Inactive schoolchildren spent more time on MVPA (M1-M2=14.7, 95% CI=8.9, 20.6) on PEday+than on Day no-PE (Figure1); however, the time that activeschoolchildren (M1-M2=7, 95% CI=-

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