During the COVID-19 pandemic, physical inactivity and being overweight increased in children, especially those from lower socioeconomic backgrounds. Additionally, a decrease in motor performance has been increasingly reported; however, there is a lack of meaningful data on the relationship between these findings and socioeconomic status. Therefore, we examined the BMI, BMI z score, the prevalence of overweight/obesity, and motor performance (based on lateral jumping, the standing long jump, and the 6-min run) among three cohorts from timelines before (2016) and during the pandemic (2020, 2021), using a cohort sequential design. Our analysis revealed that all parameters examined showed a significant negative trend over time. For children with a low social burden, the trend was statistically detectable only for lateral jumping and the 6-min run. For children with a high social burden, the prevalence of overweight/obesity increased from 4.2% to 5.4% between 2016 and 2021. The prevalence of being underweight also increased from 3.4% to 4.3% during this time. Motor performance decreased from 11.3% to 12.3%, except in the standing long jump. Children with a high social burden showed significantly lower results (7.4% to 9.6%). Thus, our data confirm an increase in both measurements of overweight/obesity and underweight, as well as a decrease in motor performance under the pandemic conditions, especially in children from socioeconomically deprived backgrounds. These findings affirm the urgent need for action regarding health promotion measures, especially for children with high social burdens.

Sarcopenic obesity is increasingly found in youth, but its health consequences remain unclear. Therefore, we studied the prevalence of sarcopenia and its association with cardiometabolic risk factors as well as muscular and cardiorespiratory fitness using data from the German Children’s Health InterventionaL Trial (CHILT III) programme. In addition to anthropometric data and blood pressure, muscle and fat mass were determined with bioelectrical impedance analysis. Sarcopenia was classified via muscle-to-fat ratio. A fasting blood sample was taken, muscular fitness was determined using the standing long jump, and cardiorespiratory fitness was determined using bicycle ergometry. Of the 119 obese participants included in the analysis (47.1% female, mean age 12.2 years), 83 (69.7%) had sarcopenia. Affected individuals had higher gamma-glutamyl transferase, higher glutamate pyruvate transaminase, higher high-sensitivity C-reactive protein, higher diastolic blood pressure, and lower muscular and cardiorespiratory fitness (each p < 0.05) compared to participants who were ‘only’ obese. No differences were found in other parameters. In our study, sarcopenic obesity was associated with various disorders in children and adolescents. However, the clinical value must be tested with larger samples and reference populations to develop a unique definition and appropriate methods in terms of identification but also related preventive or therapeutic approaches.

Addressing physical literacy (PL) has become increasingly relevant to counteract sedentary behaviour in children and youth. We developed an assessment tool to measure and evaluate the promotion of individual PL and its four subdomains: motivation and confidence (the affective dimension), physical competence (physical dimension), knowledge and understanding (cognitive dimension), and participation in physical activity. Within this cross-sectional study, we tested 567 children aged 6–12 years from four primary schools that differed in socioeconomic status (SES). A subsequent exploratory factor analysis conducted to examine the conformity revealed a five-factor structure. The five factors explained 39.8% of the total cumulative variance. Children with a low SES yielded lower scores in all subdomains except participation in physical activity. This effect was most pronounced in motor skills (p < 0.001, r = 0.28). Among the children with a low SES, 16.9% were overweight and 17.4% were obese, compared to 11.5% and 5.4%, respectively, for those with a high SES (p < 0.001). In conclusion, although the assessment tool was largely in line with the postulated structure, further adjustments are necessary in terms of participation and motivation. Nevertheless, this holistic view of PL, taking SES into account, should enable the focused promotion of health and health literacy.

Juvenile obesity is associated with insulin resistance, among other comorbidities. In the pathogenesis of insulin-resistance-related diseases, including obesity and diabetes, Vitamin D deficiency is very common. Therefore, the relationship between insulin resistance, body composition, vitamin D level, and cardiorespiratory fitness in obese children and youth were analyzed based on the Children’s Health InterventionaL Trial III project, Germany. Data on vitamin D levels and homeostatic model assessment (HOMA) indices were available from 147 participants (52.4% female; 90.5% obese; 12.3 ± 2.3 years, BMI: 30.5 ± 5.2 kg/m2, BMI standard deviation score (BMI-SDS): 2.52 ± 0.46). Vitamin D levels correlated negatively with the HOMA index, BMI, BMI-SDS, abdominal circumference, and body fat percentage but positively with relative cardiorespiratory fitness (p < 0.05 in each case). In the backward stepwise linear regression analysis, body fat (in kg; β = 0.403) and vitamin D levels (β = −0.154) explained 21.0% of the variance in the HOMA index. In summary, increased body fat and lower vitamin D levels are associated with increased HOMA indices in overweight and obese children and adolescents. In order to prevent potential negative consequences, including the development of manifest Type 2 diabetes, a healthy lifestyle with a vitamin-D-enriched diet and more time spent outdoors should be promoted.

Background: The aim of this study was to analyze the inhibitory and promotive factors of psychosocial health in the context of childhood obesity, incorporating physical fitness as an additional, potentially relevant predictor. Methods: The sample comprised cross-sectional data of 241 children and adolescents with obesity and overweight from the German Children’s Health InterventionaL TriaL III program (12.5 ± 2.1 years; 51.9% girls). Demographics and lifestyle patterns were assessed via parent reports. Anthropometric data and physical fitness in relation to body weight (W/kg) were measured. Children and adolescents completed standardized questionnaires (GW-LQ-KJ, FSK-K) to assess health-related quality of life (HRQOL) and five dimensions of self-concept (scholastic, social, physical, behavioral, and self-worth). Results: Multiple linear regression analysis showed that HRQOL was significantly related to relative physical fitness (W/kg; β = 0.216, p = 0.011) as were scholastic (β = 0.228, p = 0.008) and social self-concept (β = 0.197, p = 0.023). Increasing body mass index (BMI) Z-scores, age, physical activity (hours/day), low parental educational levels, and/or migration background were negatively associated with three subdomains of self-concept (physical, behavioral, self-worth; all p < 0.05). Conclusion: The results emphasize BMI Z-scores, age, physical activity, migration background, and parents’ educational level as relevant predictors of psychosocial health in the context of childhood obesity. Additionally, this study adds physical fitness as a key determinant of HRQOL and self-concept. To enable the development of more effective weight management, therapeutic strategies should therefore consider addressing these aspects and improving physical fitness in particular not only for weight loss but also to strengthen psychosocial health.