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This systematic review aimed to synthesize evidence of cross-sectional studies on the associations between physical activity, cardiometabolic risk factors and vitamin D concentrations in children and adolescents. The search was performed in PubMed, SciELO, LILACS, Scopus, MEDLINE and SPORTDiscus. Cardiometabolic risk factors included obesity, insulin resistance, systemic arterial hypertension and unfavorable changes in the lipid profile (low levels of high-density lipoprotein, elevated low-density lipoprotein and triglycerides). Cross-sectional design studies published between 2007 and 2019 were included whether they evaluated the relationship between vitamin D and physical activity and/or vitamin D and cardiometabolic risk factors. Fourteen studies were selected, involving 8340 children and adolescents. The main results found were a significant inverse relationship between vitamin D levels and cardiometabolic risk factors. All studies (n = 8) that tested association between physical activity and 25-hydroxyvitamin D (25 (OH) D) concentrations showed a significant and direct relationship between them. In addition, nine out of eleven studies that tested the association between 25 (OH) D and body mass index reported an inverse and significant relationship between 25 (OH) D and obesity. In conclusion, sufficient concentrations of vitamin D are related to a more favorable cardiometabolic profile, and children and adolescents who are obese or insufficiently active have a higher risk of present hypovitaminosis D.

Objective: The aim of this study was to analyze which equation best estimates maximal heart rate (HRmax) for the pediatric population according to body mass. Data source: We performed a meta-analysis (PROSPERO No. CRD42020190196) of cross-sectional studies that aimed to validate or develop HRmax equations and that had children and adolescents as samples. The search was conducted in Scopus, Science Direct, Web of Science, PubMed, and Biblioteca Virtual em Saúde with the descriptors “prediction or equation,” “maximal heart rate,” “maximum heart rate,” “determination of heart rate,” children, and adolescent. The TRIPOD Statement tool was used to assess the methodological quality and the relevant data were extracted for analysis. The meta-analysis was conducted in the Comprehensive Meta-Analysis, adopting p<0.05 and a 95% confidence interval (CI). Data synthesis: In total, 11 studies were selected, of which 3 developed predictive equations, 10 performed external validity of the preexisting models, and 1 incremented values related to equations already developed. The results of the methodological quality analysis showed a moderate rating in most studies. The 164 + (0.270 × HRres) – (0.155 × body mass) + (1.1 × METs) + (0.258 × body fat percent) (r=0.500, 95%CI 0.426–0.567, p<0.001) and 166.7+ (0.46 × HRres) + (1.16 × maturation) (r=0.540, 95%CI 0.313–0.708, p<0.001) equations presented stronger correlations with measured HRmax in nonobese adolescents. The predictive model developed by 208 – (0.7 × age) showed a greater accuracy among the possible models for analysis (SDM=-0.183, 95%CI -0.787 to -0.422, p=0.554). No specific predictive equation was found for obese adolescents. Conclusions: Future research should explore new possibilities for developing predictive equations for this population as a tool to control exercise intensity in the therapeutic management of childhood and adolescent obesity.

PURPOSE: Recently, doubts have been raised concerning the validity of the 20-m shuttle run test (20mSRT) to predict cardiorespiratory fitness (CRF) in youth. Despite these doubts, authors continue to provide powerful evidence that CRF can be predicted reliably using the 20mSRT albeit using contrasting models. Therefore, we aimed to compare a new linear model with an alternative allometric model to predict CRF (peak oxygen uptake, 𝑉 ̇O2peak) using 20mSRT. METHODS:The study included 148 adolescents (43% girls), aged 13.37 ± 1.84 years.Adolescents were randomly assigned to validation (n = 91) and cross-validation (n = 57) groups.𝑉 ̇O2peak was measured using a gas analyser in both maximal exercise tests in the laboratory as well as 20mSRT. Multiple linear regression methods were applied to develop the linear models using 20mSRT (Laps), BMI and body fat percentage. Alternative allometric models were also proposed/fitted using 20mSRT (Laps), height and body mass. RESULTS:The criterion validity of both the linear and the allomeric models were found to be acceptable R 2 =82.5% and 82.7% respectively, providing reassuring evidence that the 20mSRT can be used with confidence to predict CRF. However, the allometric model identified a heightto-mass ratio, not dissimilar to the inverse BMI (known to be a measure of leanness), to be associated with CRF. The allometric model also revealed that the rise in energy cost (𝑉 ̇O2peak) with increasing laps was exponential. This will more accurately reflect the non-linear rise in energy demand of shuttle running as the test progresses to exhaustion. CONCUSIONS: These observations provided powerful evidence that allometric models are more than satisfactory in terms of both criterion AND construct validity when predicting CRF (𝑉 ̇O2peak) using the 20mSRT.

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Introduction: The prevalence of childhood obesity has increased and is associated with the development of several chronic diseases. Moderate-intensity continuous training is recommended as the main exercise method for treating obesity. However, in overweight and obese individuals, high-intensity interval training models have similar or greater fat reduction potential than moderate-intensity continuous training. Objective: This study aimed to compare the effects of 12 weeks of moderate-intensity continuous training and high-intensity interval training on cardiometabolic parameters, body composition, and cardiorespiratory fitness in obese adolescent boys. Methods: Fifty-six obese boys, aged 10-16 years old, were included. Anthropometric measurements, blood pressure, body composition, oxygen consumption, glucose, insulin, and the lipid profile were assessed. Participants were assigned to moderate-intensity continuous training (n=20), high-intensity interval training (n=20), and control (n=16) groups. The moderate-intensity continuous training sessions consisted of 90 minutes of cycling/walking exercises and the high-intensity interval training sessions consisted of 15 minutes of warm-up, 15-18 minutes of interval exercises, and 15 minutes of cool-down. Both were performed three times a week. A two-way mixed-model factorial analysis of variance (ANOVA) with repeated measures was used. Results: In the high-intensity interval training group, there was an increase in relative and absolute oxygen consumption and a reduction in diastolic blood pressure. However, in the moderate-intensity continuous training group, there were increases in relative oxygen consumption and high-density lipoproteins, as well as reductions in anthropometric measurements, fat mass, and triglycerides. Conclusion: Moderate-intensity continuous training may be a better protocol for the reduction of fat mass, anthropometric measurements, and improvement of the lipid profile, while high-intensity interval training may be more effective in improving blood pressure among obese boys. Both exercises improve cardiorespiratory fitness. Level of evidence II; Therapeutic studies - investigation of treatment results.

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