Caffeine (1,3,7-trimethylxanthine) is one of the most widely consumed performance-enhancing substances in sport due to its well-established ergogenic effects. The use of caffeine is more common in aerobic-based sports due to the ample evidence endorsing the benefits of caffeine supplementation on endurance exercise. However, most of this evidence was established with cycling trials in the laboratory, while the effects of the acute intake of caffeine on endurance running performance have not been properly reviewed and meta-analyzed. The purpose of this study was to perform a systematic review and meta-analysis of the existing literature on the effects of caffeine intake on endurance running performance. A systematic review of published studies was performed in four different scientific databases (Medline, Scopus, Web of Science, and SportDiscus) up until 5 October 2022 (with no year restriction applied to the search strategy). The selected studies were crossover experimental trials in which the ingestion of caffeine was compared to a placebo situation in a single- or double-blind randomized manner. The effect of caffeine on endurance running was measured by time to exhaustion or time trials. We assessed the methodological quality of each study using Cochrane’s risk-of-bias (RoB 2) tool. A subsequent meta-analysis was performed using the random effects model to calculate the standardized mean difference (SMD) estimated by Hedges’ g and 95% confidence intervals (CI). Results: A total of 21 randomized controlled trials were included in the analysis, with caffeine doses ranging between 3 and 9 mg/kg. A total of 21 studies were included in the systematic review, with a total sample of 254 participants (220 men, 19 women and 15 participants with no information about gender; 167 were categorized as recreational and 87 were categorized as trained runners.). The overall methodological quality of studies was rated as unclear-to-low risk of bias. The meta-analysis revealed that the time to exhaustion in running tests was improved with caffeine (g = 0.392; 95% CI = 0.214 to 0.571; p < 0.001, magnitude = medium). Subgroup analysis revealed that caffeine was ergogenic for time to exhaustion trials in both recreational runners (g = 0.469; 95% CI = 0.185 to 0.754; p = 0.001, magnitude = medium) and trained runners (g = 0.344; 95% CI = 0.122 to 0.566; p = 0.002, magnitude = medium). The meta-analysis also showed that the time to complete endurance running time trials was reduced with caffeine in comparison to placebo (g = −0.101; 95% CI = −0.190 to −0.012, p = 0.026, magnitude = small). In summary, caffeine intake showed a meaningful ergogenic effect in increasing the time to exhaustion in running trials and improving performance in running time trials. Hence, caffeine may have utility as an ergogenic aid for endurance running events. More evidence is needed to establish the ergogenic effect of caffeine on endurance running in women or the best dose to maximize the ergogenic benefits of caffeine supplementation.

Background: Numerous meta-analyses have assessed the efficacy of creatine supplementation in increasing muscle strength. However, most have not considered the effect of the participants’ age, training duration, or other confounding variables on strength outcomes. Therefore, the purpose of this study was to consider the effect of these variables on the potential efficacy of creatine supplementation and resistance training for improving measures of muscle strength. Methods: Four databases were searched (MEDLINE, Scopus, Embase, and SPORTDiscus) with a search end date of 22 May 2024. Twenty-three studies were included, with 20 studies involving males (447 male participants), 2 studies involving females (40 female participants), and 1 study involving both males and females (13 male participants and 9 female participants). Results: In comparison with a placebo, creatine supplementation combined with resistance training significantly increased upper-body (WMD = 4.43 kg, p < 0.001) and lower-body strength (WMD = 11.35 kg, p < 0.001). Subgroup analyses showed a trend for greater upper-body strength improvements for males on creatine compared with females on creatine (p = 0.067, Q = 3.366). Additionally, males who consumed creatine combined with resistance training significantly increased both upper- and lower-body strength, whereas females showed no significant gains. There was a trend indicating greater lower-body strength gains from high-dose creatine compared with lower doses (p = 0.068, Q = 3.341). No other variables influenced the effect of creatine supplementation. In conclusions, creatine supplementation with resistance training enhances upper- and lower-body muscle strength in adults aged < 50, with greater benefits likely to be seen in males than females.

Background: Both listening to music during warm-up and consuming caffeine before exercise have been independently shown to enhance athletic performance. However, the potential synergistic effects of combining these strategies remain largely unexplored. To date, only two studies have reported additional benefits to combining music during warm-up with a caffeine dose of 3 mg/kg on taekwondo-specific performance tasks. However, these studies did not evaluate whether this combination produces additive or synergistic effects on other types of sports performance. The present study aimed to assess the effects of listening to music alone or combined with caffeine intake on performance in the Wingate anaerobic test (WAnT) in physically active subjects. Methods: Twenty-four physically active male participants took part in this randomized, double-blind, crossover experiment. Participants underwent WAnT performance evaluations under three conditions: (i) no intervention (control; CON); (ii) music plus placebo (Mus + PLA), involving the intake of a placebo (maltodextrin) 60 min prior and self-selected high-tempo music during warm-up; and (iii) music plus caffeine (Mus + CAF), involving the intake of 3 mg/kg of caffeine 60 min prior and self-selected high-tempo music during warm-up. Under all conditions, participants wore the same Bluetooth headphones (with or without music), performed a 10 min standardized warm-up, and completed the 30 s WAnT with a load of 7.5% of their body weight on a calibrated ergometer. Power output was recorded at a frequency of 1 Hz throughout the exercise. The Feeling Scale was assessed both before and after the exercise test, while heart rate (HR) and the rating of perceived exertion (RPE) were measured immediately following the exercise. Results: Mus + PLA and Mus + CAF significantly improved peak power, mean power, and total work compared with CON (p < 0.05). Furthermore, peak power was higher in Mus + CAF than in Mus + PLA (p = 0.01). Post-exercise HR and RPE showed no significant differences across conditions (p > 0.05). Regarding the Feeling Scale (FS) before exercise, the Mus + PLA and Mus + CAF conditions showed significantly higher scores than CON (p < 0.05), while no differences were found after exercise. The perceived fitness metrics displayed no significant differences among conditions (p > 0.05), except for self-perceived power, which was higher in Mus + CAF than in CON (p = 0.03). Conclusions: Self-selected music during warm-up, either alone or combined with caffeine, significantly enhanced several WAnT performance metrics, including peak power, mean power, and total work. Remarkably, combining music with caffeine further improved peak power and increased self-perceived power compared with music alone. While listening to self-selected music during warm-up provided measurable benefits on anaerobic exercise performance, the combination of music and caffeine demonstrated additive effects, making it the optimal strategy for maximizing anaerobic performance.

Background: Inorganic nitrate (NO₃⁻) may enhance muscle contractility and blood flow via nitric oxide production, offering potential ergogenic benefits. However, most studies have focused on males, and its effects in females during high-intensity, short-duration exercise remain unclear. Objective: This review assessed the acute effects of nitrate supplementation on muscle strength, power, and sprint performance in healthy females. Methods: A comprehensive literature search was conducted in PubMed, Web of Science, Scopus, SPORTDiscus, and Cochrane CENTRAL, from inception to July 2025. Randomized controlled trials (RCTs) that examined the effects of oral inorganic nitrate (e.g., beetroot juice or nitrate salts) in healthy females were included. Eligible studies involved (i) healthy women aged 18–30, (ii) nitrate supplementation vs. placebo, and (iii) outcome measures of muscle strength (e.g., MVC), power (e.g., countermovement jump height, peak power), or sprint performance (e.g., sprint time or repeated sprint ability). Studies were excluded if they did not report sex-specific results or lacked relevant physical performance outcomes. Random-effects meta-analyses were conducted for each outcome. Results: Nitrate supplementation had small, non-significant effects on muscle strength (SMD = 0.10, 95% CI: −0.10 to 0.30, p > 0.05) and sprint performance (SMD = 0.14, 95% CI: −0.13 to 0.41, p > 0.05). A statistically significant, small-to-moderate improvement was observed in power (SMD = 0.38, 95% CI: 0.06 to 0.69, p < 0.05). Sensitivity analyses confirmed robustness of the power result. The certainty of evidence ranged from low to moderate based on the GRADE assessment. Conclusions: Inorganic nitrate supplementation may modestly enhance power in healthy females but does not appear to significantly improve muscle strength or sprint performance. These findings highlight the importance of sex-specific research in sports nutrition to guide targeted supplementation strategies for female athletes.

Objective: This study aimed to perform a comprehensive meta-analysis of randomized controlled trials examining the effectiveness of whole-body vibration training (WBVT) on muscle performance in healthy women. Methods: A systematic search of studies available up to 30 May 2024 was conducted using seven databases, including PubMed, EMBASE, Web of Science, Scopus, CINAHL, PEDro, and the Cochrane Library. Studies with a randomized and controlled protocol in which the effect of WBVT on muscle performance variables was compared to that of a) a non-exercise intervention or b) exercise intervention in healthy women were assessed for eligibility. The methodological quality of the included studies was assessed using the PEDro scale. Meta-analyses were performed using random effects models, and the results were expressed as standardized mean differences (SMDs) with corresponding 95% confidence intervals (95% CIs). Results: A total of 21 randomized controlled trials, encompassing 748 healthy women, was included in the meta-analysis. WBVT demonstrated significantly greater effects on muscle strength and power when compared with the non-exercise control groups with regard to knee extension (SMD = 0.534, 95% CI: 0.303 to 0.766, p < 0.001), leg press (SMD = 0.794, 95% CI = 0.424 to 1.163, p < 0.001), ankle plantar flexion (SMD = 0.462, 95% CI: 0.019 to 0.904, p = 0.041), and the countermovement jump performance (SMD = 0.470, 95% CI: 0.211 to 0.729, p < 0.001). However, WBVT significantly improved only the countermovement jump performance (SMD = 0.338, 95% CI: 0.037 to 0.640, p = 0.028) when compared with the exercise control groups. Subgroup analyses revealed that longer periods (≥ 12 weeks) of WBVT resulted in greater benefits for both muscle strength and power compared to the non-exercise control group. Additionally, higher frequencies (> 30 Hz, SMD = 0.736, p < 0.001; ≤ 30 Hz, SMD = 0.284, p = 0.109) provided greater benefits for improving muscle strength. Last, post-menopausal women (post-menopausal, SMD = 0.561, p = 0.001; pre-menopausal, SMD = 0.354, p = 0.076) obtained greater benefits in muscle power with WBVT than pre-menopausal women. Conclusions: WBVT is efficacious in improving lower-body muscle strength and power in healthy women. However, the potential benefits of WBVT compared to other exercise interventions were only associated with an enhancement in countermovement jump performance. Longer periods (≥ 12 weeks) of WBVT resulted in greater benefits for both muscle strength and power compared to the non-exercise control group. Additionally, higher vibration frequencies (> 30 Hz) provided greater improvements in muscle strength, while post-menopausal women reaped greater benefits in muscle power than pre-menopausal women.

Despite considerable evidence on high-intensity interval training (HIIT) for cardiovascular benefits, overlapping studies and lack of systematic synthesis hinder understanding of its full effects and optimal prescription. This umbrella review synthesizes evidence and summarizes the cardiovascular benefits of HIIT across diverse populations. We searched Embase, PubMed, Web of Science, and Cochrane Library for systematic reviews and meta-analyses on effects of HIIT on cardiovascular health. Evidence was stratified by population type, overlapping evidence was handled by predefined criteria, quality was assessed using AMSTAR 2, and results were visualized using forest plots. Initially, 1017 studies were retrieved, of which 54 were included. The results revealed that HIIT significantly improved blood pressure (SBP: -5.43 to -2.73 mmHg; DBP: -4.35 to -2.41 mmHg), resting heart rate (-4.35 to -2.17 bpm), and left ventricular ejection fraction (3.51% to 5.52%). Compared with other exercise modalities such as moderate-intensity continuous training, HIIT showed significant improvements in left ventricular ejection fraction (3.13% to 3.24%), left ventricular end-diastolic diameter (-4.69 to -2.55 mm), and flow-mediated dilation (0.35% to 2.57%), with comparable effects on blood pressure and heart rate. HIIT demonstrates advantages over other exercise modalities in improving cardiac structure and volume, with comparable effects on blood pressure and heart rate. These benefits were observed across cardiovascular, metabolic, and apparently healthy populations. However, the current evidence does not support protocol-specific recommendations such as long-interval versus short-interval HIIT, and direct comparisons of different HIIT protocols are needed.