Top 10 research questions related to body composition

Systematically Observed Movement Integration in a Low Socioeconomic School District: A Cross-Sectional, Observational Study

PURPOSE

To describe teacher's integration of activity into general education classroom time (ie, movement integration-MI).

DESIGN

Cross-sectional, observational.

SETTING

Eight elementary schools in a rural, low-income school district.

PARTICIPANTS

Elementary classroom teachers (N = 48).

MEASURE

Classroom teachers were observed using the System for Observing Student Movement in Academic Routines and Transitions (SOSMART) on random, unannounced days during the 2015-16 academic year.

ANALYSIS

Descriptive statistics were calculated for the frequency and types of MI being used.

RESULTS

Of the 9398 SOSMART scans completed, students engaged in movement in 41.3% of the scans. Student movement was observed to be teacher directed in 14.4% and nonteacher directed in 26.9% of scans. Nonteacher-directed movement consisted mostly of transitions ( M = 99.5%) in which movement occurred as a result of preestablished classroom rules, protocols, and organization.

CONCLUSION

This is one of the first studies to provide objective information about MI. These descriptive data lay the groundwork for future correlational and experimental research that can lead to the development of effective intervention design to increase MI use in schools.

A novel body circumferences-based estimation of percentage body fat

Anthropometric measures of body composition are often used for rapid and cost-effective estimation of percentage body fat (%BF) in field research, serial measurements and screening. Our aim was to develop a validated estimate of %BF for the general population, based on simple body circumferences measures. The study cohort consisted of two consecutive samples of health club members, designated as ‘development’ (n 476, 61 % men, 39 % women) and ‘validation’ (n 224, 50 % men, 50 % women) groups. All subjects underwent anthropometric measurements as part of their registration to a health club. Dual-energy X-ray absorptiometry (DEXA) scan was used as the ‘gold standard’ estimate of %BF. Linear regressions where used to construct the predictive equation (%BFcal). Bland–Altman statistics, Lin concordance coefficients and percentage of subjects falling within 5 % of %BF estimate by DEXA were used to evaluate accuracy and precision of the equation. The variance inflation factor was used to check multicollinearity. Two distinct equations were developed for men and women: %BFcal (men)=10·1−0·239H+0·8A−0·5N; %BFcal (women)=19·2−0·239H+0·8A−0·5N (H, height; A, abdomen; N, neck, all in cm). Bland–Altman differences were randomly distributed and showed no fixed bias. Lin concordance coefficients of %BFcal were 0·89 in men and 0·86 in women. About 79·5 % of %BF predictions in both sexes were within ±5 % of the DEXA value. The Durnin–Womersley skinfolds equation was less accurate in our study group for prediction of %BF than %BFcal. We conclude that %BFcal offers the advantage of obtaining a reliable estimate of %BF from simple measurements that require no sophisticated tools and only a minimal prior training and experience.

Physical Activity and Changes in Adiposity in the Transition from Elementary to Middle School

OBJECTIVES

This study examined the longitudinal associations of objectively measured physical activity, sedentary behavior, and diet quality with two measures of adiposity and a measure of weight status.

METHODS

A total of 658 children from 21 elementary schools (45.1% boys; 40% white, 33% black, 9% Hispanic, and 18% other race/ethnicity) were assessed at least twice in fifth, sixth, and/or seventh grade. Fat mass index (FMI), percent body fat (PBF), and BMI were calculated from body weight, standing and seated heights, and bioelectrical impedance (BIA) measured each year.

RESULTS

At follow-up, both FMI and PBF decreased among boys and increased among girls, while BMI increased in both boys and girls. After controlling for race/ethnicity, parent education, and maturity offset at baseline, growth curve analyses showed that moderate-to-vigorous physical activity (MVPA) was significantly and negatively associated with FMI, PBF, and BMI for both boys and girls. After forming tertiles of fifth grade MVPA, least-square means for FMI, PBF, and BMI were examined by grade and gender. For both boys and girls, higher MVPA was associated with lower FMI, PBF, and BMI at all three grade levels. The relationships between sedentary behavior and diet quality and FMI, PBF, and BMI were not consistent for boys or girls.

CONCLUSIONS

As boys and girls transitioned from elementary to middle school, children who participated in higher levels of MVPA maintained more favorable levels of two indicators of adiposity and a measure of weight status. These findings support the need for interventions to help children meet current public health guidelines for physical activity.