Background: Physical education classes are widely accepted as one of the most effective settings for promoting physical activity and health and have often been used to implement physical activity interventions. The aim of this pilot study was to test a physical education intervention program on physical activity levels and physical fitness in a sample of school-age children. Methods: Participants were a convenience sample of 50 children (34 experimental group and 16 in the comparative group) aged between 6 and 11 years old (Mean = 8.28 years). A 21-week intervention was implemented, consisting of high-intensity and physical fitness-focused exercises, in addition to a once-a-month extra class nutritional education. The following variables were evaluated before and post-intervention: physical fitness, sedentary behavior (SB), light physical activity (LPA), moderate physical activity (MVA), and vigorous physical activity (VPA). Propensity score analyses calculated the average treatment effect on the treated (ATET) within a quasi-experimental framework. Results: Physical fitness variables showed improvements after the intervention, specifically for agility (ATET = -0.67 s; p < 0.001), cardiorespiratory fitness (ATET = 89.27 m; p = 0.045), lower limbs power (ATET = 4.47 centimeters; p = 0.025), and speed (ATET = -1.06 s; p < 0.001). For physical activity and SB levels, there were no improvements after intervention implementation. Conclusion: The intervention program showed preliminary effectiveness to improve physical fitness of children, but not SB nor physical activity.

Background: Low levels of physical fitness are associated with metabolic disorders in adults. However, this relationship has been little explored in children and adolescents. The aim of the present study was to investigate whether there is an association between physical fitness related to health and the presence of metabolic risk in schoolchildren. Methods: The sample for this cross-sectional study was composed of 1251 schoolchildren of both genders between 7 and 17 years of age. Three indicators of physical fitness related to health were evaluated: cardiorespiratory fitness (CRF), flexibility and abdominal resistance. The continuous metabolic syndrome score (cMetS) was calculated by using the sum of the Z scores of the following indicators: body mass index (BMI), systolic blood pressure, glucose, total cholesterol, high- and low-density lipoprotein cholesterol (HDL-c and LDL-c) and triglycerides. Subsequently, the cMetS was dichotomized, considering the presence or absence of metabolic risk. The data were analyzed using prevalence ratio (PR) values and 95% confidence intervals (CI), using Poisson regression. Results: A higher prevalence of metabolic risk was found among students with low levels of CRF (PR: 1.48; CI: 1.10–1.98) and abdominal resistance (PR: 1.45; CI: 1.08–1.95). No association with flexibility was found. Conclusions: Low levels of CRF and abdominal resistance are associated with the presence of metabolic risk in schoolchildren.

Key words: Adolescent; children; school; obesity; cardiovascular diseases

Objective: To verify the association between screen time and cardiorespiratory fitness with the presence of metabolic risk in schoolchildren in an isolated and clustered manner. Methods: Cross-sectional study with 1.200 schoolchildren from Santa Cruz do Sul-RS. Screen time and cardiorespiratory fitness were evaluated. The continuous metabolic risk score was calculated by summing the Z score of the waist circumference, systolic blood pressure, glucose, triglycerides, total cholesterol, low-density lipoprotein (LDL-C) and high-density lipoprotein (HDL-C). Results: Children (34.3%) and adolescents (48.2%) had high screen time, while 44.3% of the children and 53.3% of the adolescents were unfit in relation to cardiorespiratory fitness. Regarding the relation of screen time/cardiorespiratory fitness, 14.7% of the children and 26.9% of the adolescents presented high screen time and low levels of cardiorespiratory fitness. The presence of metabolic risk was shown in children (17.1%) and adolescents (14.7%). The presence of metabolic risk was directly associated with low levels of cardiorespiratory fitness in children and adolescents. When analyzed in clusters, the metabolic risk in children was 11% more prevalent in subjects with low screen time/unfit and 12% in subjects with high screen time/unfit, whereas in adolescents, the prevalence of metabolic risk was also higher in those with low screen time/unfit (8%) and high screen time/unfit (7%). Conclusions: The presence of metabolic risk in children and adolescents was associated with low levels of cardiorespiratory fitness, independent of screen time, in an isolated or clustered manner.