Multiple regression models for predicting MVPA from IPAQ-SF variable.

<p>Multiple regression models for predicting MVPA from IPAQ-SF variable.</p

Demographic characteristics of participants and their average school day physical activity with average and days method.

<p>Demographic characteristics of participants and their average school day physical activity with average and days method.</p

Comparison of IPAQ-SF and Two Other Physical Activity Questionnaires with Accelerometer in Adolescent Boys

<div><p>Self-report measures of physical activity (PA) are easy to use and popular but their reliability is often questioned. Therefore, the general aim of the present study was to investigate the association of PA questionnaires with accelerometer derived PA, in a sample of adolescent boys. In total, 191 pubertal boys (mean age 14.0 years) completed three self-report questionnaires and wore an accelerometer (ActiGraph GT1M) for 7 consecutive days. The PA questionnaires were: International Physical Activity Questionnaire-Short Form (IPAQ-SF), Tartu Physical Activity Questionnaire (TPAQ), and the Inactivity subscale from Domain-Specific Impulsivity (DSI) scale. All three questionnaires were significantly correlated with accelerometer derived MVPA: the correlations were 0.31 for the IPAQ-SF MVPA, 0.34 for the TPAQ MVPA and -0.29 for the DSI Inactivity scale. Nevertheless, none of the questionnaires can be used as a reliable individual-level estimate of MVPA in male adolescents. The boys underreported their MVPA in IPAQ-SF as compared to accelerometer-derived MVPA (respective averages 43 and 56 minutes); underreporting was more marked in active boys with average daily MVPA at least 60 minutes, and was not significant in less active boys. Conversely, MVPA index from TPAQ overestimated the MVPA in less active boys but underestimated it in more active boys. The sedentary time reported in IPAQ-SF was an underestimate as compared to accelerometer-derived sedentary time (averages 519 and 545 minutes, respectively).</p></div

Descriptive statistics of the subjects (N = 191).

<p>Descriptive statistics of the subjects (N = 191).</p

Correlations between accelerometer and self-reported PA in 13-14-years-old boys.

<p>Correlations between accelerometer and self-reported PA in 13-14-years-old boys.</p

Bland and Altman plots with difference in mean time spent in MVPA for the IPAQ-SF and accelerometer GT1M ActiGraph.

<p>In the Bland and Altman plot, difference between two measurements is plotted against their mean. Mean and 95% confidence intervals of the difference are shown with blue lines. If there is no bias (in this case, over- or underestimating), then mean error should be close to zero. In addition, most measurement points should ideally be within the 95% confidence limits of the mean error (that is, within the lower and the upper blue line). International Physical Activity Questionnaire (IPAQ); moderate to vigorous physical activity (MVPA).</p

Venn diagrams showing the number of children defined as compliant or non-compliant according to average and days methods.

<p>Venn diagrams showing the number of children defined as compliant or non-compliant according to average and days methods.</p

Mean (± SD) characteristics of the subjects at baseline measurement.

a<p>Significantly different from underweight boys;</p>b<p>significantly different from normal weight boys;</p>c<p>significantly different from overweight boys;</p>d<p>significantly different from obese boys (P<0.05);</p><p>Biological age is years from APHV (age at peak height velocity); BMI, body mass index; TB BMD, total body bone mineral density; FN BMD, femoral neck bone mineral density; LS BMD, lumbar spine bone mineral density; SED, sedentary time; MVPA, moderate and vigorous physical activity.</p><p>Mean (± SD) characteristics of the subjects at baseline measurement.</p

TB BMD changes during pubertal growth spurt.

<p>Comparing four different groups – underweight, normal weight, overweight and obese pubertal boys. APHV - age of peak height velocity.</p

The change of PA levels during the study period in four different groups of participants.

a<p>Significantly different from underweight boys;</p>b<p>significantly different from normal weight boys; (P<0.05);</p>1<p>significantly different from baseline PA level;</p>2<p>significantly different from PA level after 12 month;</p><p>SED, sedentary time; LPA, light physical activity; MPA, moderate physical activity; VPA, vigorous physical activity; MVPA, moderate to vigorous physical activity.</p><p>The change of PA levels during the study period in four different groups of participants.</p