Background/Objectives: The potential of relative grip strength as a biomarker for cardiovascular risk in college students is not well understood. Methods: Blood pressure status and grip strength metrics were analysed with multivariate logistic regression and restricted cubic spline models, utilising nationwide cross-sectional data from 42,591 Chinese college students. Results: After adjustment, higher absolute grip strength increased hypertension risk (High-level OR = 2.66; 95% CI: 2.21–3.20). In contrast, higher relative grip strength not only reduced risk overall (High-level OR = 0.41; 95% CI: 0.36–0.46) but also demonstrated consistent protective effects across all BMI subgroups (e.g., OR = 0.83 in overweight/obese individuals). Conclusions: Relative grip strength may present a valuable biomarker for cardiovascular risk assessment and the easy identification of at-risk individuals in all BMI categories.

Background/Objectives: The potential of outdoor physical activity as an intervention strategy to promote height growth velocity via stimulating growth hormone secretion and vitamin D synthesis has been scarcely investigated. The present study aimed to investigate the associations between outdoor physical activity duration and height growth velocity, and differences in gender, age, exposure time period (daily, school days vs. weekends), and body mass index (BMI) category. Methods: We performed a secondary analysis of longitudinal data from the 2019–2020 Chinese National Survey on Students’ Constitution and Health. The analytic sample included 5029 adolescents aged 9–18 years. High or low height growth velocity was defined as sex- and age-specific percentiles. Associations of high height growth velocity with outdoor activity duration (≥1 h, ≥2 h) on school days and weekends were investigated using multivariable logistic regression models. Analyses were stratified by sex, age group (9–12, 13–15, 16–18 years), and BMI category (normal weight, overweight, and obese). Results: Results from this cross-sectional analysis indicate that ≥1 h of daily outdoor physical activity is significantly associated with higher height growth velocity among normal-weight boys aged 9–15 years (OR range: 1.71–2.01) and girls aged 9–12 years (OR = 1.68). The positive association increased with ≥2 h (ORs up to 7.96). Consistently positive associations were found for activity during the school day compared to weekends. No significant associations were found in overweight and obese children. Conclusions: Ensuring adequate daily outdoor physical activity—especially on weekends—for at least two hours may be an important potential strategy to promote height growth in normal-weight children and adolescents. Interventions should consider differences in weight status and timing of activity.

Background: The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) has increased rapidly in pediatric populations. Evidence on the cost-effectiveness of pediatric MASLD screening strategies remains limited. Methods: A decision tree combined with a Markov state-transition model was developed to evaluate the cost-effectiveness of three WHtR-based two-stage screening strategies among children aged 6–14 years in Beijing, China: WHtR combined with ultrasound (S1), WHtR combined with FibroScan^® (S2), and WHtR combined with magnetic resonance imaging-proton density fat fraction (MRI-PDFF) (S3), compared with no screening (S4). All screening strategies were combined with lifestyle modification programs, including dietary and exercise management. Model inputs were derived from the published literature, national survey data, and expert consensus. Costs and quality-adjusted life years (QALYs) were estimated from a healthcare system perspective over a 10-year time horizon, with a 3% annual discount rate. Incremental cost–utility ratios (ICURs) were calculated, and extensive one-way, two-way, and probabilistic sensitivity analyses were performed. Results: Our model indicated that, at a willingness-to-pay (WTP) threshold of $30,584.0 per QALY, corresponding to three times the gross domestic product (GDP) per capita of China, S2 was identified as the optimal strategy. At a higher WTP threshold of $71,415.5 per QALY, based on the GDP per capita of Beijing, S3 became the most cost-effective option. All three screening strategies were more cost-effective than no screening across both thresholds. Sensitivity analyses demonstrated that utility values for fibrosis stages and the response rate of the lifestyle modification program were the most influential parameters, and probabilistic sensitivity analysis confirmed the robustness of the baseline findings. Conclusions: To the best of our knowledge, this is the first cost-effectiveness analysis for pediatric MASLD in China. Model-based estimates suggest that early screening for MASLD in children using WHtR-based screening strategies is cost-effective, with FibroScan^® preferred in settings with average economic development and MRI-PDFF preferred in more affluent regions. These findings underscore the importance of context-specific implementation of early MASLD screening strategies in pediatric populations to mitigate long-term disease burden.

Backgrounds: To examine the association between stages of exercise behavior change, as defined by the transtheoretical model (TTM), and obesity progression among Chinese children and adolescents, with attention to gender and urban–rural differences. Methods: A total of 5006 Chinese children and adolescents aged 9–18 years were assessed in 2019 and followed up in 2020. Participants were categorized into five TTM stages: precontemplation, contemplation, preparation, action, and maintenance. Logistic regression models evaluated the associations between the TTM stages and obesity outcomes, including incident obesity and transitions from normal or overweight to obesity. Analyses were stratified by gender and urban–rural residence, and interaction effects were tested. Results: Compared to the maintenance stage, precontemplation (OR = 2.08, 95% CI: 1.45–2.99) and contemplation (OR = 1.48, 95% CI: 1.05–2.08) stages had higher obesity risk, with similar trends in follow-up incident obesity (precontemplation: OR = 1.63, 95% CI: 1.17–2.28; contemplation: OR = 1.47, 95% CI: 1.10–1.98). These associations were more pronounced among boys and rural residents. Significant interactions were observed between TTM stages, sex (p = 0.029), and residence (p = 0.005) in obesity transition. Conclusions: Exercise behavior stages are associated with obesity progression, particularly among boys and rural children. These findings underscore the importance of stage-specific interventions tailored to individual readiness for behavior change and contextual factors.

Background/Objectives: The association between sleep deprivation and mental well-being in school-aged children and adolescents has been well documented, but the specific relationship between sleep debt and mental well-being remains unclear. This study aimed to evaluate the association between sleep debt and mental well-being in school-aged children and adolescents. Methods: This cross-sectional study included 4967 children and adolescents aged 9–18 years from eight provincial-level regions in China, using data from a multicenter school-based survey conducted within the framework of the Chinese National Survey on Students’ Constitution and Health (CNSSCH). Participants self-reported relevant sleep parameters, and the sleep debt was calculated based on the difference in sleep duration between weekdays and weekends. The main outcome was mental well-being. Adjusted covariates were age, sex, urban–rural residence, body mass index (BMI), vital capacity, and waist-to-hip ratio. Results: A total of 4967 children and adolescents were included (mean [SD] age 12.77 [2.59] years; 2475 [49.83%] girls) with 3176 participants classified as having higher mental well-being and 1791 participants classified as having lower mental well-being. After adjustment for covariates, sleep debt was associated with greater odds of lower mental well-being (adjusted odds ratio [aOR] = 1.095; 95% CI, 1.050–1.143; p < 0.001). Although statistically significant, the magnitude of this association was modest. In stratified analyses, each quartile increase in sleep debt was associated with 17.8% higher odds of lower mental well-being in boys (95% CI, 8.6–27.8%), 33.8% higher odds in girls (95% CI, 23.8–44.6%), 25.3% higher odds in urban students (95% CI, 16.3–35.0%), and 28.2% higher odds in rural students (95% CI, 17.6–39.7%) (all p < 0.001). In addition, weekend sleep patterns significantly interacted with the sleep debt–mental well-being association (p for interaction < 0.05), while age-specific nonlinear patterns involving nap duration were observed among adolescents aged 15–17 years (p for nonlinearity = 0.004). Conclusions: Sleep debt showed a statistically significant but modest cross-sectional association with lower mental well-being. Numerically larger subgroup-specific estimates were observed among girls and rural students. Given the cross-sectional design, these findings should not be interpreted as evidence of causality. Despite its modest magnitude, the association may have public health relevance at the population level. The observed patterns involving weekend sleep and age-specific nap duration warrant further evaluation in longitudinal and, where appropriate, intervention studies.