EXERCISE AND QUALITY OF LIFE

The assessment of Body mass index (BMI) was conducted on a sample of 2432 pre-school children 4-7 years old in Autonomic Province of Vojvodina. The aim of this assessment was to determine changes in BMI values depending on age and gender, as well as determining the presence of obesity in observed population. The sub-samples was defined by age in intervals of 0.5 decimal years. The differences in BMI values were tested with Analysis of Variance, and the statistical significance was set at p<0.01. The results showed statistically significant differences in BMI values in relation to age (F=7.345, p=0.0001) and gender (F=6.232, p=0.013) of children. There were found noticeably higher values of BMI with elderly children compared to their younger counterparts. In addition, all the boys, regardless to age had higher BMI values than girls did. Obesity categorization of children in relation to BMI values showed that 73.6% of children had normal BMI values and only 5.4% of them were categorized in extreme obese group.


Introduction
Overweight and obesity is a medical and social problem of the global future mankind.As a health problem, obesity in the United States occurs in 18.8% of children with an average age of 12, while in Switzerland the percentage is much lower -6.5 [1].In the EU countries, 38.2% of school age children were overweight and of these, 10% were obese [2].In Serbia, 6.4% of children and adolescents aged 7-19 years were obese [3].The prevalence of overweight in children has markedly increased over the past few decades in France, as in all Western countries.The result of Péneau et al. [4] shows that the overall trend in prevalence of overweight children between 1996 and 2006 was stable at population aged from 6 to 15. Obesity in children appears to increase every year, a trend which was observed in all highly industrialized countries [5].Health experts and researchers talk about a paediatric 'obesity epidemic' with exponentially increasing rates of obesity and overweight.Although levels of Australian paediatric overweight remain high, the prevalence of overweight and obesity seems to have flattened and also have not followed the anticipated exponential trajectory [6].The prevalence of overweight among US children and adolescents increased between 1980 and 2004 [7].
Body mass index (BMI), is one of the most common and widely applied measures of obesity.The correlation of BMI with fat is high, but at the same time for different terminals [8].The emergence of obesity and excessive amounts of adipose tissue has an impact on cognitive, motor, emotional, and social development of children.Bradley et al. [9], suggest that children with high BMI before starting school do not have problems with socialization, but school entering experience may cause problems that lead to anxiety and depression.
The aim of this study was to analyse differences in BMI for boys and girls aged 4-7 years.

The sample of subjects
The sample of subjects was drawn randomly from a number of pre-school children in Vojvodina (Serbia), a total of 2432 children aged 4-7 (1391 boys and 1048 girls).All subjects and their parents were fully informed about the nature and demands of the study and all parents voluntarily gave their informed consent for their child, to participate in the study, which was approved by the University's Ethical Advisory Commission in accordance with the Helsinki Declaration.All measurements were carried out in the morning (from 8:00 to 12:00 h) by the same-trained measurers, who used the same measuring instruments and protocols.Decimal age of subjects was calculated according to the International Biological Program (IBP) and treated the children's age on the day of measurement and testing.

The sample of measures
Body weight and body height were measured without shoes and body mass index (BMI) was calculated (kg/m 2 )."Underweight", "Normal", "Over-weight" and "Obese" were defined using the age-and sexspecific criteria [10,11]

Statistical procedures
Differences between distinguished taxonomic groups in motor variables and variable for the assessment of general cognitive ability were determined using multivariate analysis of variance (MANOVA), and univariate analysis of variance (ANOVA).
All data were analysed using IBM SPSS Statistics (version 19.0) program for Windows.

Results
Results of BMI values for boys an girls divided into seven categories are presented in Table 1 as Mean + (SD).⃰ Statistically significant differences between age groups; ⃰ statistically significant differences between genders Results obtained by testing differences of BMI between age groups showed statistically significant difference between them (F = 6.343; p = 0.000) in addition to significant differences obtained with respect to gender (F = 6.232; p = 0.013).However, interaction of these two factors did not show statistically significant difference indicating that children within age groups did not differ significantly regarding the values of BMI.Nevertheless, results presented on Graph 1 are showing that regardless to age group that boys are constantly ahead of girls in BMI values

Figure 1. Average values of BMI for boys and girls divided into seven age categories
Testing the differences between groups that was formed based on normative values for BMI and gender, showed that there was statistically significant difference between genders, however in some age categories these differences between genders were not statistically (F=0,081; p=0,970).
In table 2 are presented mean values with standard deviations for BMI values for boys and girls divided into four categories.⃰ Statistically significant differences between genders; level of significance is set to p=0.001

Discussion
The main finding in this study is that there were found noticeably higher values of BMI with elderly children compared to their younger counterparts.It is well known that BMI is widely used as an indicator of body fat because of its simplicity but it is not the most accurate predictor of body fat percentages, especially with children [12].It must be taken into consideration that with the growth and period of child's development, BMI is very artificial value representing no true body proportions, and one should be careful when coming to conclusion, because BMI does not measure adiposity directly.BMI is highly correlated with adiposity and it varies with age and sex in children [13].
Nevertheless, all the boys in this study, regardless to age had higher BMI values than girls did, which is in line with some previous studies [14,15].Obesity categorization of children in relation to BMI values showed that 73.6% of children had normal BMI values and only 5.4% of them were categorized in extreme obese group.Even though percent of obese children in this research considers being low, prevention of obesity in preschool children should be of importance, for it is estimated that obese children are most likely to be obese in adolescence and as adult.Overweight and obesity are chronic disorders that have multiple causes and significant impact on both physical and psychological health on children, thus it should be more investigated.

Table 1 .
BMI Mean Values and Standard Deviations for age groups and gender

Table 2 .
Mean Values and Standard Deviations for BMI regarding gender