Association of physical activity and sedentary behavior at school with cardiovascular risk factors in adolescents

Abstract The association of moderate to vigorous physical activity and sedentary behavior performed in the school context with cardiovascular risk factors is unclear. Thus, the purpose of this study was to evaluate whether MVPA and SB during school time are associated with single and clustered cardiovascular risk factors in 10- to 16-year-old school students. This study used the baseline data from a non-randomized controlled clinical trial (“MEXA-SE”) conducted on 6th to 9th-grade students from schools in Florianopolis, Brazil. Skinfolds, resting blood pressure, 20-m shuttle-run test, fasting glucose, triglycerides, total cholesterol, high-density lipoprotein cholesterol, and white blood cell counts were obtained. MVPA and SB were objectively measured with accelerometers. A minimum of 180 minutes was considered valid school-time for analysis. Multiple linear regression adjusted for age, sex and habitual physical activity was used. School-time MVPA was positively associated with the peak VO2 (β = 0.17 ml.kg.min-1), and inversely associated with sum of four skinfolds (β = -0.96 mm), diastolic blood pressure (β = -0.36 mmHg), systolic blood pressure (β = -0.301 mmHg); triglycerides (β = -1.49 mg.dL-1), and clustered cardiovascular risk factors (β = -0.123). School-time SB was positively associated with clustered cardiovascular risk factors (β = 0.033). In conclusion, independently of habitual physical activity level, school-time MVPA and a lower time in SB were associated to single and clustered cardiovascular risk factors. Thus, the promotion of strategies aimed increase MVPA and reduce SB at school may prevent the onset and early accumulation of cardiovascular risk factors in adolescence.

The effect of an intervention on physical activity of moderate-and-vigorous intensity, and sedentary behavior during adolescents' time at school

INTRODUCTION

This study evaluated the effect of an intervention on the engagement in physical activity (PA) and sedentary behavior (SB) of sixth to ninth grade students during school-time, physical education (PE) classes, and recesses at two public schools in Florianopolis, SC, Brazil.

METHOD

Schools were divided into control and experimental groups. Participants wore accelerometers during school-time, and PA and SB were estimated for school-time, PE classes and recesses at the baseline and after the intervention. The intervention was composed of four components: changes were made in the PE classes, including giving instruction to teachers; sports equipment was made available for use during recesses; educational sessions on the format of classes were conducted; folders and posters were distributed. Data was analyzed using an Analysis of Covariance for repeated measures comparing baseline data with post intervention data, and for independent samples when comparing control and intervention groups.

RESULTS

A low proportion of engagement in PA and a large engagement in SB was observed on the baseline. PA decreased in the intervention group during PE classes, while it increased in the control group with regard to school-time, PE classes, and recess. The intervention group accumulated more SB during school-time and PE classes after the intervention, while a decrease in the control group's SB during school-time was observed.

CONCLUSION

The intervention was not effective in increasing PA or decreasing SB. Environmental and school's organizational factors impact how interventions are conducted, and should be considered beforehand.

Predictors of dropout in the school-based multi-component intervention, 'Mexa-se'

To identify the predictors of dropout in the 'Mexa-se' intervention according to the body mass index (BMI) category. This was a controlled, non-randomized study. The intervention included: (i) increase in the intensity of physical activities (PA) in physical education (PE) classes; (ii) active recess; (iii) educational sessions on PA, nutrition and body image; and (iv) educational materials. Dropout was considered when students dropped out of intervention, or did not reach 75% attendance in PE classes. The independent variables were gender, age, study period, socioeconomic status, BMI, PA, screen time, food consumption, health perception, attitudes toward PA, self-efficacy for PA, perception of the school environment, body image and self-esteem. Binary logistic regression analysis was used. The dropout rate was 26.8%. In the total sample and among students with an adequate BMI, there was a greater probability of dropout with an increase in age. For overweight students, increased age and socioeconomic status, and studying in the afternoon period were predictors of dropout from the intervention. Socio-demographic factors were predictors of dropout from the 'Mexa-se' intervention; the associated factors differed based on the BMI category.

Exposure to simultaneous sedentary behavior domains and sociodemographic factors associated in public servants

DOI: http://dx.doi.org/10.5007/1980-0037.2017v19n4p469 Exposure to sedentary behavior may contribute to health problems. This study aimed to estimate the prevalence of exposure to simultaneous sedentary behavior domains and verify associated sociodemographic characteristics among technical and administrative servers of a Brazilian university. This is a cross-sectional epidemiological study carried out with 623 technical and administrative servers. Sedentary behavior was identified through a questionnaire in the following domains: commuting (active / passive), sitting time at work, daily time spent watching television and computer use (≥3 hours / day). Sociodemographic variables were age, sex and educational level. The prevalence of servers that had one, two, three and four simultaneous sedentary behavior was 28.4%, 43.2%, 22.5% and 4.3%, respectively. Women were more likely to have three sedentary behavior simultaneously (OR = 1.61, CI 95% = 1.02, 2.56). Servers with 9-11 years of schooling were less exposed to two (OR = 0.27, CI 95% = 0.17, 0.44), three (OR = 0.39, CI 95% = 0.23, 0.66) and four (OR = 0.22, CI 95% = 0.07; 0.69) sedentary behavior simultaneously and those over 12 years of schooling were less likely of having two (OR = 0.22, CI 95% = 0.10; 0.49) and three (OR = 0.15, CI 95% = 0.05, 0.46) sedentary behavior simultaneously. More than half of servers have two sedentary behavior during the week. Having sedentary behavior in more than one domain simultaneously was associated with sex and educational level.

School-Based Interventions to Improve Cardiorespiratory Fitness in Adolescents: Systematic Review with Meta-analysis

BACKGROUND

School-based intervention can contribute to the promotion of cardiorespiratory fitness (CRF) in adolescents. However, it is neces sary to systematize how intervention strategies and the methodological characteristics of studies influence the effects of CRF interventions.

OBJECTIVE

A meta-analysis review of school-based intervention studies aimed at increasing CRF in adolescents (10-19 years of age) was conducted.

METHODS

A search for studies was conducted using the Medline, Web of Science, LILACS, PsycINFO, Embase, Scopus, SPORTDiscus and Cochrane databases and the reference lists of the selected studies. The peer selection process included consideration of school-based randomized or non-randomized controlled trials with a duration ≥12 weeks published in English, Portuguese or Spanish, and with some CRF measures. The methodological quality of the studies was also assessed. The standardized mean differences (SMDs) and 95 % confidence intervals (95 % CIs) were calculated as an effect measure.

RESULTS

Forty publications of 30 interventions were included in the review, and 25 of these were meta-analysed. The effects of CRF interventions were moderate and significant (SMD = 0.68, 95 % CI 0.45-0.90), with high heterogeneity (I (2) = 97 %). The effect size varied significantly according to the age group, sample size, intervention environment, strategies in experimental groups, CRF priority in the study, CRF test and indicator, session length, weekly frequency, intervention duration and presentation of results by sex.

CONCLUSION

Interventions in the school environment seem to have a positive effect on CRF among adolescents, but there is high heterogeneity between studies. Some intervention characteristics can explain better effects on CRF (e.g. exercise sessions in addition to physical education classes; primary focus on this outcome; combination of aerobic and resistance exercises; classes lasting ≥60 min; frequency of three times weekly; and intensity control).

Sedentary patterns, physical activity and health-related physical fitness in youth: a cross-sectional study

Background

Strong evidence indicates that moderate-vigorous physical activity (MVPA) is positively associated with fitness in youth, independent of total sedentary-time. Sedentary-time appears negatively associated with fitness only when it replaces MVPA. However, whether different sedentary-patterns affect health-related fitness is unknown.

Methods

The associations between MVPA and sedentary-patterns with physical fitness were examined in 2698 youths (1262 boys) aged 13.4 ± 2.28 years. Sedentary-time (counts · minute⁻¹ < 100) and PA were objectively measured by accelerometry. Each break (≥100 counts · min⁻¹ < 2295) in sedentary-time and the frequency of daily bouts in non-prolonged (<30 min) and prolonged (≥30 min) sedentary-time were determined. The FITNESSGRAM® test battery was used to assess fitness. A standardized fitness composite-score (z-score) was calculated by summing the individual z-scores of the five tests adjusted to age and sex.

Results

Positive associations between MVPA and fitness were observed in both boys (β = 0.013, 95% CI: 0.005; 0.021) and girls (β = 0.014, 95% CI: 0.006; 0.022), independent of sedentary-patterns. Modest associations were found for the breaks in sedentary-time with fitness (β = 0.026, 95% CI: 0.009; 0.042), independent of total sedentary-time and MVPA in boys. In girls, non-prolonged sedentary bouts were positively associated with fitness (β = 0.014, 95% CI: 0.003; 0.024), independent of total sedentary-time and MVPA.

Conclusions

These results reinforce that, independent of the time and patterns of sedentary behavior, MVPA is consistently associated with fitness in youth. Modest and inconsistent associations were found for sedentary behaviors. Breaking-up sedentary-time in boys and non-prolonged sedentary bouts in girls were positively associated with fitness, independent of total sedentary-time and MVPA. In order to enhance youth’s fitness, public health recommendations should primarily target MVPA, still, suggestion to reduce and break-up sedentary-time may also be considered.

Stages of Behavior Change for physical activity and associated factors among technicaladministrative servers of a federal university

DOI: http://dx.doi.org/10.5007/1980-0037.2016v18n4p471 The benefits that the regular practice of physical activity (PA) provides to health and its importance in preventing and fighting chronic diseases. The aim of this study was to identify the Stages of Behavior Change (SBC) for PA among technicaladministrative servers and its association with sociodemographic and health risk factors. This cross-sectional study investigated 622 technical-administrative servers (337 women) from a Brazilian federal university. SBC for PA, sociodemographic information (gender, age, marital status and educational level) and health risk factors (inadequate eating habits, excessive alcohol consumption, smoking, commuting and PA at work) were collected through questionnaires. Multinomial regression with adjustment for the hierarchical level was applied and significance level of 5% was adopted. The distribution of technical-administrative servers in SBC for PA identified prevalence of 9.1% and 6.5% in the pre-contemplation stage, 24.6% and 33.5% in contemplation, 33.3% and 22 6% in preparation, 5.6% and 12.2% in action and 27.4% and 25.2% in maintenance stages between men and women, respectively. Lower odds ratio of being in the preparation stage was identified among women (OR=0.62; CI95%=0.41; 0.93) while those with inadequate eating habits were more odds to be in the “pre-contemplation + contemplation” (OR=2.77; CI95%=1.85; 4.15) and preparation stages (OR=1.75; CI95%=1.12; 2.70). Over 60% of technical-administrative servers are insufficiently active (pre-contemplation, contemplation and preparation stages) and factors associated with SBC were female sex and inadequate eating habits.