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).

Rising ambient temperatures and the increasing frequency of training and competition in hot climates have made heat stress a major challenge in football. Under such conditions, players experience greater cardiovascular and thermoregulatory strain, faster glycogen use, higher perceived exertion, and progressive impairment in repeated high-intensity actions and decision-making. These responses have intensified interest in nutritional strategies that might complement heat acclimation, hydration/electrolyte planning, cooling practices, and recovery management. This narrative review critically synthesizes current evidence on nutritional interventions that may be relevant to football performed in the heat, with emphasis on hydration and electrolyte replacement, carbohydrate–protein strategies, taurine, branched-chain amino acids (BCAAs), creatine, menthol, antioxidant- and nitrate-related approaches, and selected multi-ingredient products. Across the available literature, hydration/electrolyte planning and carbohydrate–protein feeding remain the practical foundation, menthol appears most consistently useful for perceptual cooling, creatine seems safe and potentially helpful for repeated-sprint support, and taurine is promising but still supported by relatively few trials. By contrast, evidence for BCAAs, antioxidants, nitrates, and caffeine as stand-alone heat strategies, as well as for many compound supplements, remains inconsistent, context-specific, or too indirect for strong football-specific endorsement. Overall, the evidence base remains heterogeneous in study quality, protocol design, exercise mode, and sport specificity. A substantial proportion of the available data is derived from cycling, endurance, or laboratory heat-exercise models rather than football-specific trials. Accordingly, any practical recommendation should be interpreted cautiously and embedded within broader heat-management strategies. Future work should prioritize ecologically valid randomized controlled trials in football or football-like intermittent protocols, with transparent reporting of dose, timing, perceptual outcomes, and match-relevant performance measures.

Background: Acute exercise rapidly reorganizes skeletal-muscle metabolism. The metabolite pools that remain responsive with aging, and their relationship to baseline oxidative state, remain incompletely defined. Methods: We analyzed 135 metabolites measured in 93 skeletal-muscle biopsies from 47 participants and matched baseline transcriptomic measurements. We tested paired post–pre changes, biochemical-class enrichment, baseline associations with a four-pathway oxidative transcript-state score, and participant-held-out prediction of acetylcarnitine response. False-discovery-rate control was applied within each analysis family. Bootstrap confidence intervals and a baseline-adjusted sensitivity analysis quantified predictive performance. Results: In exercise-trained older adults, 17 metabolites changed after acute exercise after FDR correction. Acetylcarnitine increased, whereas free carnitine, malate, ATP, and choline decreased. No exercise-trained-versus-normally active response contrast survived correction. The CoA–glutathione-annotated feature and NAD⁺ remained associated with the oxidative transcript-state score after adjustment for group and sex (partial $\rho =0.512$ and 0.514; both $q=0.042$). A four-metabolite TabPFN model predicted acetylcarnitine change with an out-of-fold $R^2$ of 0.412 (95% CI, 0.079–0.641), similar to the reference model ($R^2=0.399$, 95% CI, 0.054–0.625). Baseline acetylcarnitine alone achieved an AUC of 0.817 (95% CI, 0.680–0.941) for a twofold-response endpoint. Additional metabolites provided only modest incremental information after baseline adjustment. Conclusions: Acute exercise induced heterogeneous, distributed remodeling of skeletal-muscle metabolite pools. Baseline redox-related molecular state showed cross-omic coherence and contained information about subsequent acetylcarnitine response. Transcriptomic augmentation and more complex predictive architectures provided limited incremental benefit.