Background: This study investigated the effects of combined Rhodiola rosea (RHO) and caffeine (CAF) supplementation on lower limb explosive power and fatigue recovery in volleyball players, aiming to validate their potential synergistic effects. Methods: A randomized, double-blind, placebo-controlled design was implemented involving 48 male volleyball athletes allocated into four groups: placebo (CTR), Rhodiola rosea (RHO), caffeine (CAF), and combined (RHO + CAF). Over four weeks, participants engaged in twice-weekly high-intensity lower limb resistance training, with performance evaluated through multiple tests, including two-step-approach jump height, countermovement jump (CMJ), five-jump test (5 JT), continuous 20 vertical jumps, and intermittent jump recovery alongside Rate of Perceived Exertion (RPE) assessments. Results: Results showed that the combined supplementation (RHO + CAF) group exhibited significant improvement across multiple performance metrics. In particular, the combined group demonstrated the highest increases in jump height and the least power decline during high-frequency jumps, outperforming the CTR and other supplementation groups (p < 0.05). Additionally, RHO + CAF supplementation significantly lowered RPE scores, particularly in the final week of training, indicating improved perceived fatigue and recovery. Conclusions: This study suggests that combining RHO and CAF optimizes high-intensity performance by enhancing explosive power, reducing fatigue, and improving recovery, presenting an effective nutritional strategy for volleyball athletes.

Objectives: This study aimed to evaluate the efficacy of various nutritional supplements in enhancing endurance performance and subjective thermal perception in athletes exposed to high-temperature environments through a systematic review and network meta-analysis. Methods: A comprehensive search was conducted in PubMed, Embase, Web of Science, Cochrane Library, and EBSCOhost from inception to January 2025. Studies were included if they evaluated the effects of nutritional supplements on either endurance performance or subjective thermal perception in athletes under heat stress. Two independent reviewers screened the literature, extracted data, and assessed the risk of bias. A network meta-analysis was performed using R software (version 4.3.1). The search was limited to English-language publications and employed both MeSH and free-text terms related to “athletes,” “nutritional supplements,” and “exercise performance,” using Boolean operators (AND/OR) to construct the strategy. Results: Twenty-five randomized controlled trials (RCTs) involving 552 participants were included, yielding 22 comparisons: 18 assessed endurance performance, and 11 assessed subjective perception. Standardized mean differences (SMDs) and posterior probabilities (P-scores based on Bayesian ranking) were calculated using random-effects and Bayesian models. Menthol (SMD = −1.83, 95% CI [−3.15, −0.51]; P-score = 71.04%) and taurine (SMD = 0.91, 95% CI [0.08, 1.73]; P-score = 12.75%) demonstrated significant positive effects on endurance. Menthol energy gel showed the greatest improvement in thermal comfort (SMD = 2.14, 95% CI [1.01, 3.26]; P-score = 99.54%). Conclusions: Menthol and taurine appear effective in enhancing endurance in hot environments, while menthol energy gel substantially improves perceived thermal comfort. Future research should apply stricter controls regarding environmental conditions, supplement dosage, and participant characteristics. While individual supplements may offer limited benefits, synergistic combinations may yield greater improvements in performance and comfort.

Background: Post-exercise recovery involves coordinated metabolic restoration and redox rebalancing. Although dietary polyphenols have been proposed to facilitate recovery, the metabolic mechanisms underlying their effects—particularly during the recovery phase—remain insufficiently characterized. This study aimed to investigate how polyphenol supplementation modulates post-exercise metabolic recovery using an integrative metabolomics approach. Methods: We conducted a secondary analysis of publicly available longitudinal human LC–MS metabolomics datasets from exercise intervention studies with polyphenol supplementation. Datasets were obtained from the NIH Metabolomics Workbench and MetaboLights repositories; study-level metadata were used as provided by the original investigators. Global metabolic trajectories were assessed using principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA). Targeted analyses focused on purine degradation intermediates and redox-related metabolites. Correlation-based network and pathway enrichment analyses were applied to characterize recovery-phase metabolic reorganization. Results: Exercise induced a pronounced global metabolic perturbation in both placebo and polyphenol groups. During recovery, polyphenol supplementation was associated with a partial reversion of the metabolome toward the pre-exercise state, whereas placebo samples remained metabolically displaced. Discriminant metabolite analyses identified purine degradation intermediates and oxidative stress-related lipid species as key contributors to group separation during recovery. Polyphenol supplementation attenuated recovery-phase accumulation of hypoxanthine, xanthine, and uric acid and was associated with a sustained suppression of the uric acid-to-hypoxanthine ratio. Network analyses revealed weakened correlations between purine metabolites and oxidative stress markers, along with reduced network centrality of stress-responsive metabolic hubs. Conclusions: These findings indicate that polyphenol supplementation is associated with accelerated metabolic normalization during post-exercise recovery, potentially through modulation of purine-associated oxidative pathways and system-level metabolic network reorganization.

Background: Explosive lower limb power, a critical determinant of success in volleyball, is a prime candidate for focused research. Consequently, nutritional supplements are commonly employed to gain an ergogenic edge. Despite this widespread practice, a comprehensive and evidence-based ranking of supplements for improving this key attribute is lacking, leaving athletes and practitioners without targeted evidence to guide decisions. Methods: PubMed, Web of Science, CENTRAL, and Embase were searched from inception to 1 August 2025. We included RCTs in volleyball athletes (≥14 years) with ≥1-week interventions and relevant explosive lower limb performance outcomes. A Bayesian NMA estimated effects with 95% credible intervals (CrIs) and SUCRA; certainty was appraised with CINeMA. Results: A total of 35 RCTs (n = 838 volleyball athletes) examining 13 different supplements were included. The results indicated that β-alanine was associated with the greatest improvement in vertical jump (MD 4.6; 95% CrI 1.2–7.8), followed by creatine (MD 3.7; 0.57–6.9) and caffeine (MD 2.1; 0.06–4.1). It also appeared to be the most promising method for substantially increasing lower limb peak power (SMD 1.1; 0.21–2.0). No statistically significant improvement was found in lower limb mean power, and no serious adverse events were reported. Conclusions: Among volleyball athletes, β-alanine appeared most promising effective supplement for enhancing key components of explosive lower limb performance, specifically vertical jump height and peak power. Creatine and caffeine are also effective for improving vertical jump height. However, these findings are based on low-to-moderate certainty of evidence; they should be interpreted with caution and regarded as preliminary. Supplement strategies should be individualized by age and competitive level; further, high-quality, standardized randomized controlled trials are warranted to validate these initial observations.

Background: Astaxanthin is a lipid-soluble carotenoid with antioxidant and anti-inflammatory properties, but its effects on exercise performance and post-exercise recovery remain uncertain. This systematic review and meta-analysis aimed to evaluate the effects of astaxanthin supplementation on exercise performance and recovery-related biomarkers in healthy participants and athletes. Methods: This review followed PRISMA 2020 guidelines. PubMed, Web of Science, Embase, EBSCO, the Cochrane Library, and CNKI were searched from inception to January 2026. Randomized controlled trials comparing oral astaxanthin supplementation with placebo or control were included. Performance outcomes included VO₂max, time-trial or endurance-related performance, and maximal workload or power output. Recovery-related outcomes included creatine kinase, lactate dehydrogenase, malondialdehyde, interleukin-6, and related biomarkers. Standardized mean differences with 95% confidence intervals were pooled. Results: Twenty-four RCTs were included. Astaxanthin significantly reduced creatine kinase levels (SMD = −0.45, 95% CI: −0.83 to −0.07). Lactate dehydrogenase also favored astaxanthin (SMD = −0.93, 95% CI: −1.39 to −0.48), although heterogeneity was substantial. No significant effects were observed for malondialdehyde or interleukin-6. Astaxanthin did not significantly improve VO₂max, time-trial performance, or maximal workload/power output. Conclusions: Current evidence suggests that astaxanthin may be more beneficial for post-exercise recovery than for direct performance enhancement. The most consistent effect was observed for creatine kinase, whereas the LDH finding should be interpreted cautiously. Further well-powered trials with standardized dosing, duration, exercise protocols, and outcome assessments are needed.

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.