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Type of Study and Subject
An observational-analytical-comparative cross-sectional study of school-age male children aged 6 to 11 years from two elementary schools in Hermosillo, Sonora, Mexico, was conducted. Hermosillo is the capital of the state of Sonora, located in the North-West of Mexico and borders the United States to the North. The total sample was 299 children (72 from public school and 227 from private school). The calculation of the sample was made from a simple sampling with a maximum acceptable error of 5%, at a confidence level of 95% through a stratified sample design from the representativeness of the two schools [18]. A representativeness of 30% of the population was considered for each stratum, obtaining a minimum sample of 156 students (38 from public schools and 118 from private schools). To carry out this work, the parents’ authorization was obtained through an informed consent form whereby they approved the participation of their children in the study. The ethical considerations for health studies stipulated in resolution 8430 of 1993 and the Declaration of Helsinki of the World Medical Association were followed, in addition to the approval of the Research Ethics Committee of the University of Sonora.
Techniques and Instruments
The anthropometric characterization was carried out by two ISAK-certified evaluators in a conditioned area, allowing the children to wear short shorts and a thin cotton shirt. Body mass (kg) and height (m) were measured on an electronic scale equipped with a Tanita stadiometer (TBF-410GS, Arlington Heights, USA). Triceps and subscapular skinfolds were taken on the right side of the body using an anthropometric caliper (Slim Guide D1085). The final value was the average of two repetitions. The BF% was determined using the equation of Boileau et al. which considers the tricipital fold (TR) and subscapularis (SS) for its prediction [19]:
The cohort points of the curves reported by McCarthy [20] were used to define low fat, normal, overweight and obese from the 2nd, 85th and 95th percentiles. The Body Mass Index (BMI) was calculated with the Z score (BMI=kg/m2). For the categorization with overweight or obesity, the reference tables of the World Health Organization were used, using as criteria the values of the 85th and 97th percentiles specific by age and sex [2,22].
Lifestyle Assessment
The HEPALHQ validated by Guerrero et al. was applied with some modifications for its understanding by schoolchildren from 6 to 11 years of age. The interrogative instrument consisted of 27 items, which measured two dimensions, 18 evaluating eating and 9 physical activities, with a reported Cronbach’s alpha of 0.81 and a correlation coefficient (r) of 0.82 [23]. The total score of the two dimensions allows the classification of three cohort points. Those who obtained a score lower than 95 were classified as having poor eating habits, due to the presence of risk factors in their lifestyle. Participants with scores in the range of 95 to 109 were considered to have sufficient eating habits and a lifestyle with health benefits, although they also continue to present risks. Those with a score higher than 109 were considered as children with healthy eating habits and an adequate lifestyle for their health.
Finally, a questionnaire on eating habits and physical activity was applied to them through an inventory answered in a selfadministered manner. They were asked about their favourite foods and the frequency of consumption, habits while eating, favourite drinks, activities at school, during break time, in their free time, time in front of the television or electronic devices, hours of sleep. The results or frequencies were graphed to represent the trend of the habits present in the population of children of each school.
Statistical Analysis
For the analysis of the normal distribution of the data, the Anderson-Darling test was applied. Descriptive statistics were used to obtain measures of central tendency and analysis of variance (ANOVA) to determine significant differences. The comparison of means was performed using the Tukey- Kramer test. All data were examined at a 95% confidence level (p<0.05). To determine the cohort points of the score resulting from the HEPALHQ instrument, the 25th percentile values were used, between the 25th and 75th percentile and greater than the 75th percentile. Finally, a descriptive analysis was applied to the results of the frequency of food consumption and physical activity to make inferences. The statistical program SAS 6.08 by PCS was used.