Background: Childhood and adolescent overweight and obesity are major global public health concerns. High-intensity interval training (HIIT) has been increasingly investigated as a time-efficient intervention; however, evidence regarding its effects on multiple health-related outcomes and the influence of intervention characteristics remains inconsistent. Objective: The objective of this study was to evaluate the effects of HIIT on body composition, metabolic health, and cardiorespiratory fitness in children and adolescents with overweight or obesity. Methods: Systematic literature searches were conducted in PubMed, Web of Science, EBSCO, CNKI, Wanfang Data, and VIP databases. Randomized controlled trials were included. Risk of bias was assessed using the Cochrane Risk of Bias tool. Meta-analyses were conducted using random-effects models, and standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated. Heterogeneity, sensitivity analyses, publication bias, and certainty of evidence (GRADE) were also evaluated. Results: A total of 21 randomized controlled trials involving 652 participants (325 in the intervention groups and 327 in the control groups) were included. Compared with control conditions, HIIT significantly improved multiple outcomes related to body composition, metabolic health, and cardiorespiratory fitness, including BMI (SMD = −1.05), body fat percentage (SMD = −0.69), total cholesterol (SMD = −0.42), HOMA-IR (SMD = −1.00), and VO₂peak (SMD = 0.91), while no significant effect was observed on lean body mass. Subgroup analyses suggested that HIIT protocols with a load duration of less than 1 min were associated with greater improvements in several outcomes, particularly body fat percentage, total cholesterol, HOMA-IR, and VO₂peak. Conclusions: HIIT may improve body composition, metabolic health, and cardiorespiratory fitness in children and adolescents with overweight or obesity. However, the certainty of evidence varied across outcomes and was limited for some findings by heterogeneity, small sample sizes, and potential risk of bias. Further high-quality, large-scale randomized controlled trials with standardized HIIT protocols are needed to confirm these findings and clarify the influence of different training characteristics (e.g., exercise mode and interval structure).

Objective: This study aimed to explore the molecular response mechanisms of differential blood metabolites before and after 8 weeks of threshold and polarized training models using metabolomics technology combined with changes in athletic performance. Methods: Twenty-four male rowers aged 14–16 were randomly divided into a THR group and a POL group (12 participants each). The THR group followed a threshold training model (72%, 24%, and 4% of training time in low-, moderate-, and high-intensity zones, respectively), while the POL group followed a polarized training model (78%, 8%, and 14% training-intensity distribution). Both groups underwent an 8-week training program. Aerobic endurance changes were assessed using a 2 km maximal rowing performance test, and untargeted metabolome analysis was conducted to examine blood metabolomic changes before and after the different training interventions. Aerobic endurance changes were assessed through a 2 km maximal rowing test. Non-targeted metabolomics analysis was employed to evaluate changes in blood metabolome profiles before and after the different training interventions. Results: After 8 weeks of training, both the THR and POL groups exhibited significant improvements in 2 km maximal rowing performance (p < 0.05), with no significant differences between the groups. The THR and POL groups had 46 shared differential metabolites before and after the intervention, primarily enriched in sphingolipid metabolism, glutathione metabolism, and glycine, serine, and threonine metabolism pathways. Nine unique differential metabolites were identified in the THR group, mainly enriched in pyruvate metabolism, glycine, serine, and threonine metabolism, glutathione metabolism, and sphingolipid metabolism. A total of 14 unique differential metabolites were identified in the POL group, predominantly enriched in sphingolipid metabolism, glycine, serine, and threonine metabolism, aminoacyl-tRNA biosynthesis, and glutathione metabolism. Conclusions: The 8-week THR and POL training models demonstrated similar effects on enhancing aerobic performance in adolescent male rowers, indicating that both training modalities share similar blood metabolic mechanisms for improving aerobic endurance. Furthermore, both the THR group and the POL group exhibited numerous shared metabolites and some differential metabolites, suggesting that the two endurance training models share common pathways but also have distinct aspects in enhancing aerobic endurance.

This cross-sectional study examined the relative age effect (RAE) in Chinese youth table tennis players and compared its magnitude across competitive level