Background: The improvement of performance and skill indices of volleyball players can affect their success rate. Therefore, the present study aimed to evaluate the effects of acute caffeine supplementation of varied doses on collegiate volleyball players’ specific performance and skills. Method: This research was a randomized, double-blind, crossover design study in which 15 male volleyball players aged 18 to 25 years participated voluntarily. Participants were randomly placed in three different conditions, including 3 mg of caffeine per kilogram of body weight (C3), 6 mg of caffeine per kilogram of body weight (C6), and a placebo (PLA) with a one-week wash-out period between exercise trials. The supplement was taken 60 min before each exercise session. Ball throwing, hand movement speed, agility, Sargent’s jump and handgrip, and attacking and serving skill tests were measured and analyzed to check the performance and skill of the volleyball players. Results: This study showed a significant increase in agility test in C6 compared with the PLA condition (p = 0.02). Additionally, there was a significant improvement in Sargent’s jump in C6 compared with PLA (p = 0.00) and C6 compared with the C3 condition (p = 0.00). Also, attacking skill significantly increased in C3 compared with PLA (p = 0.00) and C6 compared with the PLA condition (p = 0.00). In addition, there was a significant increase in serving skill for C6 compared with PLA (p = 0.00) and C3 (p = 0.00). However, there were no significant differences in hand movement speed (p = 0.06), left handgrip (p = 0.85), right handgrip (p = 0.47), or medicine ball throwing (p = 0.22) between the three conditions. Conclusions: In conclusion, the findings of the current study suggested that a higher dose of caffeine compared with a lower dose may be more effective in movements requiring lower-body explosive power and the ability to change direction. Also, according to the findings, it seems that caffeine can lead to the improvement of complex skills, such as serving and attacking in volleyball.

Background: Artificial Intelligence (AI) is increasingly applied in endurance sports to optimize performance, enhance recovery, and personalize nutrition and supplementation. This review synthesizes current knowledge on AI applications in endurance sports, emphasizing implications for metabolic health, nutritional strategies, and recovery optimization, while also addressing ethical considerations and future directions. Methods: A narrative review was conducted using targeted searches of PubMed, Scopus, and Web of Science with cross-referencing. Extracted items included sport/context, data sources, AI methods including machine learning (ML), validation type (internal vs. external/field), performance metrics, comparators, and key limitations to support a structured synthesis; no formal risk-of-bias assessment or meta-analysis was undertaken due to heterogeneity. Results: AI systems effectively integrate multimodal physiological, environmental, and behavioral data to enhance metabolic health monitoring, predict recovery states, and personalize nutrition. Continuous glucose monitoring combined with AI algorithms allows precise carbohydrate management during prolonged events, improving performance outcomes. AI-driven supplementation strategies, informed by genetic polymorphisms and individual metabolic responses, have demonstrated enhanced ergogenic effectiveness. However, significant challenges persist, including measurement validity and reliability of sensor-derived signals and overall dataset quality (e.g., noise, missingness, labeling error), model performance and generalizability, algorithmic transparency, and equitable access. Furthermore, limited generalizability due to homogenous training datasets restricts widespread applicability across diverse athletic populations. Conclusions: The integration of AI in endurance sports offers substantial promise for improving performance, recovery, and nutritional strategies through personalized approaches. Realizing this potential requires addressing existing limitations in model performance and generalizability, ethical transparency, and equitable accessibility. Future research should prioritize diverse, representative, multi-site data collection across sex/gender, age, and race/ethnicity. Coverage should include performance level (elite to recreational), sport discipline, environmental conditions (e.g., heat, altitude), and device platforms (multi-vendor/multi-sensor). Equally important are rigorous external and field validation, transparent and explainable deployment with appropriate governance, and equitable access to ensure scientifically robust, ethically sound, and practically relevant AI solutions.

Background: Capsaicin, known for its antioxidant and antibacterial properties, may mitigate oxidative stress and inflammation associated with exercise-induced muscle damage (EIMD). This study evaluates the efficacy of capsaicin supplementation in reducing delayed-onset muscle soreness (DOMS) and enhancing strength and power in collegiate male futsal players. Methods: A randomized, double-blind, placebo-controlled crossover design was used. Twelve male futsal players participated in three testing sessions: baseline (BL), followed by capsaicin (12 mg) or placebo (PLA), with a 7-day washout period. Participants consumed the supplement 45 min before completing an EIMD protocol of 200 plyometric jumps with a 10% body-weight vest. Metrics including vertical jump height (VJH), pressure pain threshold (PPT), thigh circumference (TCM), and isokinetic and isometric strengths were assessed 48 h post-EIMD. DOMS was measured using a visual analog scale (VAS) at baseline and 12, 24, and 48 h post-EIMD. Results: Capsaicin supplementation significantly improved VJH (p = 0.009), PPT (p = 0.004), and reduced TCM (p = 0.015) compared to baseline, with superior performance in PPT and TCM reduction (p < 0.05). Capsaicin also significantly decreased VAS scores for DOMS immediately, 12, 24, and 48 h post-EIMD (p < 0.001) compared to PLA and BL. No significant differences were found in isokinetic and isometric strength metrics (p > 0.05). Conclusions: Acute capsaicin supplementation can mitigate DOMS and enhance performance markers such as VJH and PPT in collegiate futsal players. Its benefits suggest a viable nutritional strategy for recovery and performance optimization in high-intensity sports.

Background: Hormonal fluctuations across the menstrual cycle can significantly impair physical performance, neuromuscular function, and cognitive processing in female athletes, particularly during the premenstrual phase. Emerging evidence suggests that dark chocolate (DC), rich in flavonoids, polyphenols, magnesium, and theobromine, may exert anti-inflammatory, analgesic, and neuroprotective effects. This study investigated the acute effects of 85% DC supplementation on cognitive and physical performance, as well as delayed-onset muscle soreness (DOMS), in female CrossFit^® athletes across four distinct hormonal phases. Methods: In this randomized, double-blind, placebo-controlled, crossover study, fifteen trained eumenorrheic female CrossFit^® athletes completed three intervention conditions: dark chocolate (DC), placebo (PLA), and control (CON). Participants were evaluated during four distinct menstrual phases—menstrual, follicular, luteal, and premenstrual syndrome (PMS)—over three consecutive menstrual cycles. In each phase, participants consumed 30 g/day of either DC or PLA for three days, followed by performance testing on day four. Functional and cognitive performance were assessed via the CINDY WOD, handgrip strength (HGS), and Stroop tests (reaction time and correct answer percentage, CAP). DOMS was measured using a 100 mm visual analog scale at baseline and at 0, 12, 24, 48, and 72 h post-exercise. Results: DC supplementation significantly improved functional performance (CINDY WOD) across all menstrual phases, with the greatest enhancement during PMS (p < 0.01). Reaction time significantly improved during PMS (p = 0.010 vs. control; p = 0.002 vs. placebo). Additionally, DOMS was notably reduced in the luteal phase at 12 h, 24 h, and 72 h post-exercise in the DC condition compared to the control and placebo (p < 0.05). No significant differences were observed in HGS across conditions or phases (p > 0.05). Conclusions: Short-term DC supplementation may selectively enhance high-intensity functional performance and cognitive accuracy in trained female athletes, particularly during hormonally sensitive phases such as PMS. Its anti-inflammatory and neuromodulatory properties make DC a promising, non-pharmacological strategy to support female-centric recovery and performance in CrossFit^® and similar sports. Future research should explore chronic intake, mechanistic biomarkers, and individual variability across menstrual cycles.