The purpose of this study was to summarize patterns of correlations between variables and reduce a large number of variables to a smaller number of factors.
During 2005 we conducted a national, cross-sectional, multistage study among 1140 children (mean age = 10.70 ± 0.98). Principal component analysis was employed to extract the main factors out of 21 variables assessing children’s duration of physical and sedentary activities.
Eight factors emerged as important, explaining 63% of the total variance in children’s PA patterns. The combined explained variance of 3 factors for exercise was 24.1% (PA and sports after school [11.6%]; home and outside home chores, aerobics, gymnastics, sports [6.8%]; Sports for All, after-school activities [except sports] [5.7%]) and of 5 factors for sedentary activities was 38.9% (video, electronic games, and computers [10.2%]; watching TV, video, and DVD [9.5%]; homework and private lessons [7.3%]; theater cinema, use of mobile phone [6.2%]; afternoon sleep, less private lessons [5.8%]). Further analyses of the emerged factors by gender showed that boys, on a daily basis, are engaged in higher duration in physical activity and sports after school (factor 1) and in electronic games and computers (factor 2), whereas they are engaged in lower durations in factor 4 type behavior (homework and private lessons) and factor 6 type behavior (theater cinema, use of mobile phone).
Use of the above factors will inform further research and enable researchers to identify potential differences in physical and sedentary activities patterns by various environmental and sociodemographic variables. Furthermore, associations of factors by gender may inform public health programs.
Lazarou is with the Dept of Nutrition and Dietetics, Harokopio University, Athens, Greece. Soteriades is with the Dept of Environmental Health, Environmental and Occupational Medicine and Epidemiology (EOME), Harvard School of Public Health, Boston, MA 02115.