Waist Circumference and Objectively Measured Sedentary Behavior in Rural School Adolescents

Tri-axial accelerometer-assessed physical activity and its association with weight status in a sample of elementary-school children

BACKGROUND AND AIMS

Objective assessment of physical activity (PA) using accelerometers and pedometers has become more accurate and common practice in the study of childhood overweight. The study aimed: i) to compare PA levels and body shape of boys and girls, and assess compliance of active children with the PA recommendation; ii) to analyse associations between the risk of overweight and the moderate-to-vigorous physical activity (MVPA) in children.

METHODS

The sample comprised 395 children (198 girls) aged 6-10 years. Height and weight were measured, and BMI was calculated subsequently. A tri-axial accelerometer was used to obtain seven consecutive days of MVPA, as well as the weekly time being sedentary. Logistic regression analysis was used to examine the afore-mentioned relationship among the risk of obesity and MVPA, controlling for confounders.

RESULTS

After controlling for wearing time, boys spent significantly more minutes in the moderate-to-vigorous portion of PA than their female counterparts. About 47% of boys were active on week days by achieve the mean value of 60 min/day of MVPA; corresponding percentage for the weekend was just 32%. Among girls, only 22% were active on week days and 29% at the weekend. MVPA was not significantly associated with the risk of being overweight nor in female neither in male children. The final regression model revealed that girls of mothers with high educational level were less likely to be classified as overweight girls.

CONCLUSIONS

Findings revealed no significantly relation between MVPA and obesity risk among Portuguese children. Future research should extend similar design to other lifestyle features of children to clarify potential predictors of being overweight at early ages.

Movement Behaviour and Health Outcomes in Rural Children: A Systematic Review

BACKGROUND

Studies with rural children are limited, and results are divergent regarding the information on movement behaviours.

PURPOSE

to (i) describe the physical activity and sedentary behaviour in children; (ii) synthetize the year and place of publication, methodological quality, and instruments used to measure physical activity and sedentary behaviour; and (iii) to analyse the relationship between physical activity, sedentary behaviour, and health outcomes in these children.

METHODS

We use the databases PubMed, Web of Science, SPORTDiscus, Scopus, Virtual Health Library, and SciELO, considering papers published until October 2021. A total of 12,196 studies were identified, and after the exclusion of duplicate, title and abstract screening, and the full-text assessment, a total of 68 were included in the study.

RESULTS

A cross-sectional design was dominant among the studies, with sample sizes ranging from 23 to 44,631 children of both sexes. One-third of the studies were conducted in North America and Europe, and most of them used device-based measurements. Inequalities were observed regarding sex, age, economic level, race, and physical activity domains within and between the places of residence. Sociodemographic characteristics were also related to health outcomes for children living in rural and urban areas.

CONCLUSION

It is necessary to increase the evidence on movement behaviours among children living in the countries of South America and Oceania, as well as to increase the level of evidence on the role of school for physical activity in children in rural areas, given the inconsistent findings.

Body composition and prediction equations using skinfold thickness for body fat percentage in Southern Brazilian adolescents

OBJECTIVES

The purpose of this study was to: a) determine the nutritional status of Brazilian adolescents, and; b) present a skinfold thickness model (ST) to estimate body fat developed with Brazilian samples, using dual energy x-ray absorptiometry (DXA) as reference method.

METHODS

The main study group was composed of 374 adolescents, and further 42 adolescents for the validation group. Weight, height, waist circumference measurements, and body mass index (BMI) were collected, as well as nine ST-biceps (BI), triceps (TR), chest (CH), axillary (AX) subscapularis (SB), abdominal (AB), suprailiac (SI), medial thigh (TH), calf (CF), and fat percentage (%BF) obtained by DXA.

RESULTS

The prevalence of overweight in adolescents was 20.9%, and obesity 5.8%. Regression analysis through ordinary least square method (OLS) allowed obtainment of three equations with values of R2 = 0.935, 0.912 and 0.850, standard error estimated = 1.79, 1.78 and 1.87, and bias = 0.06, 0.20 and 0.05, respectively.

CONCLUSION

the innovation of this study lies in presenting new regression equations for predicting body fat in Southern Brazilian adolescents based on a representative and heterogeneous sample from DXA.