1. Caffeine is among the most widely used psychoactive substances worldwide and has been extensively studied as an ergogenic aid [1,2]. Traditional oral ingestion of caffeine has been shown to impr...

This study investigated the weight loss (WL) practices, perceptions, and eating disorders (ED) symptoms of Chinese female adolescent combat sport (CS) athletes. An adapted Rapid WL Questionnaire (RWLQ) and Eating Disorder Examination-Questionnaire 8 (EDE-Q8) were completed during the off-season of female adolescent CS athletes to provide WL practices, perceptions, and global ED score. There were 130 and 78 respondents for the adapted RWLQ and EDE-Q8, respectively. Seventy-three percent of participants purposefully engaged in WL practices. The average habitual WL was 8.0% of body mass (BM), and the average highest WL was 9.1% of BM. Participants predominantly allocated 15 + days before the weigh-in for WL (65%). Coaches were most commonly reported as the primary guides for WL (64%). Athletes engage in WL mainly to compete against lighter opponents (65%). Most participants perceived that WL had no impact on health (51%), is beneficial to performance (52%), and does not lead to unfair competition (79%). Only six percent of participants were considered as having ED symptoms. No significant differences or association in global ED scores and ED symptoms were observed across any examined dependent variables. The prevalence and magnitude of WL are high amongst Chinese female adolescent CS athletes. Most athletes adopted long-term strategies to lose a substantial percentage of their BM. Athletes’ WL practices did not differ according to their perceptions regarding the impact of WL on performance, health, or fairness. Off-season prevalence of ED symptoms and global ED score showed no significant differences or associations with athletes’ habitual WL behaviors.

Coenzyme Q10 (CoQ10) is biologically plausible as an ergogenic aid through roles in mitochondrial energy production and antioxidant defence, yet findings from randomised trials are inconsistent. This review included twenty-four studies from six databases published up to November 2025, assessing effects of CoQ10 on exercise performance, subjective fatigue and circulating CoQ10 levels in healthy adults. Randomised trials comparing CoQ10 with placebo were synthesised using a three-level model. Risk of bias was assessed with RoB2 and certainty judged with Grading of Recommendations Assessment, Development, and Evaluation. Supplementation consistently increased blood CoQ10, indicating robust biochemical responsiveness. In contrast, performance effects were small and inconsistent. In primary analyses, chronic supplementation showed a small benefit, whereas acute supplementation showed no benefit. After excluding outliers, the chronic effect was no longer stable and the acute effect remained trivial. All subgroup analyses were restricted to chronic supplementation. Within this context, aerobic endurance was significant in primary analyses but became borderline after outlier exclusion, while anaerobic and strength outcomes showed little change. Evidence for reduced subjective fatigue was suggestive and became more consistent after outlier exclusion. Benefits in trained individuals were unstable and became consistent only after outlier exclusion. No stable dose–response pattern emerged for supplementation dosage or duration. Heterogeneity and moderate-to-high risk of bias reduced certainty. Collectively, CoQ10 reliably elevates circulating levels but provides at most modest and context-dependent benefits for exercise performance, largely under chronic use. Overall, certainty is very low to low. Well-controlled randomised trials that standardise formulation, dose and duration and examine sex-specific and endurance-related responses are needed.

Background and Objectives: Evidence on the acute ergogenic effects of caffeine in adolescent athletes remains limited. This systematic review quantified acute performance-related effects and summarised adverse-event reporting in this population. Methods: PubMed and Web of Science were searched from inception to 13 May 2026 and SPORTDiscus was additionally searched from inception to 15 July 2026 for placebo-controlled studies of acute, dose-defined caffeine ingestion in adolescent athletes aged 10–19 years. Paired Hedges’ g values were synthesised separately across six outcome domains using three-level random-effects models with CR2 cluster-robust inference. Risk of bias and certainty of evidence were assessed using RoB 2 and GRADE. Safety findings were summarised narratively. Results: Thirty-five studies were included, of which 32, representing a total of 726 participants, contributed 363 effect sizes. In the primary analysis, which excluded a priori a small number of extreme combat-sport count-test effects arising from implausibly small reported standard deviations (Hedges’ g > 3.0), caffeine produced a small favourable average effect on physical performance (g = 0.33, 95% CI 0.17 to 0.49). When all effect sizes were included in a sensitivity analysis, the estimate was larger but inflated by these extreme values (g = 0.43, 95% CI 0.20 to 0.67) and was accompanied by substantial heterogeneity (I² = 84%), a prediction interval crossing the null (−0.71 to 1.58), and significant small-study asymmetry. Pooled effects were not statistically significant for sport-specific performance, perceptual response, or physiology. Cognitive findings were based on only two study clusters and were highly uncertain, while psychological outcomes were summarised narratively because the evidence was too sparse and heterogeneous for a meaningful pooled estimate. Exploratory moderator analyses did not provide reliable evidence that effects differed by caffeine dose or ingestion timing. No serious adverse events were reported, but adverse-event assessment was inconsistent. Conclusions: Acute caffeine ingestion may produce a small and uncertain benefit for selected physical-performance tasks in adolescent athletes. Adverse-event reporting was inconsistent, and current evidence is insufficient to support routine caffeine use in youth sport. These findings are specific to acute caffeine exposure under controlled experimental conditions in adolescent athletes and should not be extrapolated to children, non-athlete adolescents, repeated or chronic caffeine use, or energy-drink consumption.