Equine metabolic investigation of the phosphodiesterase-4 inhibitor ibudilast as a potential performance enhancer.

RATIONALE: Phosphodiesterase 4 (PDE4) inhibitors are a newer class of drugs that induce bronchodilation and have anti-inflammatory effects, making them susceptible to misuse as performance enhancers in competitive sports. METHODS: This study explores the metabolic conversion of PDE4 inhibitor ibudilast in thoroughbred horses after oral administration and in vitro using equine liver microsomes and Cunninghamella elegans. A liquid chromatography-high resolution mass spectrometry method was used to postulate the plausible structures of the detected metabolites. RESULTS: A total of 20 in vivo metabolites were identified under experimental conditions, including 12 Phase I and 8 Phase II conjugated metabolites. Phase I metabolites were predominantly formed through hydroxylation (mono-, di-, and tri-hydroxylation). Demethylated metabolites were also identified during this investigation. Additionally, the research detected Phase II metabolites conjugated with glucuronic and sulfonic acids. CONCLUSIONS: The data presented here can assist in detecting the PDE4 inhibitor ibudilast and uncover its illicit use in competitive sports.

Caffeine, but not paracetamol (acetaminophen), enhances muscular endurance, strength, and power.

BACKGROUND: Caffeine is one of the most popular ergogenic aids consumed by athletes. Caffeine's ergogenic effect has been generally explained by its ability to bind to adenosine receptors, thus modulating pain and reducing perceived exertion. Another pharmacological agent that may improve performance due to its analgesic proprieties is paracetamol. This study aimed to explore the effects of caffeine, paracetamol, and caffeine + paracetamol consumption on muscular endurance, strength, power, anaerobic endurance, and jumping performance. METHODS: In this randomized, crossover, double-blind study, 29 resistance-trained participants (11 men and 18 women) ingested either a placebo, caffeine (3 mg/kg), paracetamol (1500 mg) or caffeine + paracetamol 45 min before the testing sessions. The testing sessions included performing the bench press exercise with 75% of one-repetition maximum to momentary muscular failure, isokinetic knee extension and flexion at angular velocities of 60°/sec and 180°/sec, Wingate, and countermovement jump (CMJ) tests. RESULTS: Compared to placebo, isolated caffeine ingestion increased the number of repetitions performed in the bench press (p = 0.005; d = 0.42). Compared to placebo, isolated caffeine ingestion and/or caffeine + paracetamol consumption was ergogenic for strength (torque), muscular endurance (total work), or power in the isokinetic assessment, particularly at slower angular velocities (p = 0.027 to 0.002; d = 0.16 to 0.26). No significant differences between the conditions were observed for outcomes related to the Wingate and CMJ tests. CONCLUSION: This study provided novel evidence into the effectiveness of caffeine, paracetamol, and their combination on exercise performance. We found improvements in muscular endurance, strength, or power only when caffeine was consumed in isolation, or in combination with paracetamol. Isolated paracetamol consumption did not improve performance for any of the analyzed outcomes, thus calling into question its ergogenic potential.

Impact of CYP1A2 Genotypes on the Ergogenic Effects and Subjective Mood States of Caffeine Ingestion in Resistance-Trained Women.

Caffeine's metabolism is determined by CYP1A2 genotypes: AC/CC (SLOW) and AA (FAST). This trial evaluated CYP1A2 genotypes' impact on exercise and cognitive effects in 36 resistance-trained females assessed under placebo (PL) and caffeine (6 mg/kg bw anhydrous caffeine-CAF) conditions, before ingestion and throughout the session. 23andMe® (San Francisco, CA, USA) determined genotypes using saliva. Data were analyzed using two-way RMANOVA and paired-samples t-tests (p < 0.05). A significant main effect for genotype existed for leg press repetitions to failure (RTF) for CAF (p = 0.038), with the FAST group performing more repetitions than the SLOW (p = 0.027). There was a significant condition x genotype interaction for the subjective outcome index score (p = 0.045), with significant differences for time (p < 0.01) and between genotype (p < 0.001). Follow-up analysis revealed a higher total score (p = 0.028) following CAF for the FAST group and a lower total score (p < 0.01) in the SLOW group. Dizziness was reported following CAF in the SLOW group (p = 0.014; Cohen's d = 0.725). Aside from leg press RTF, subjective outcome index score, and dizziness, the genotype groups experienced similar responses to resistance exercise performance and subjective mood states following caffeine ingestion.

Combined Impact of Creatine, Caffeine, and Variable Resistance on Repeated Sprint Ability in Young Soccer Players.

There is evidence that both intra-serial variable resistance (I-sVR), as pre-activation within the post-activation performance enhancement cycle (PAPE), and creatine and caffeine supplementation increase athletic performance in isolation. However, the effect of the three conditioning factors on 30 m repeated sprint ability (RSA) performance in young soccer players is unknown. This study determined the summative and isolation effect of ergogenic aids and pre-activation in half-back squats (HBSs) with I-sVR on performance in an RSA test in young soccer players. Twenty-eight young soccer players were randomly assigned to either EG1 (n = 7, creatine + caffeine + I-sVR), EG2 (n = 7, creatine + placebo2 + I-sVR), EG3 (n = 7, placebo1 + caffeine + I-sVR), or EG4 (n = 7, placebo1 + placebo2 + I-sVR), using a factorial, four-group-matched, double-blind, placebo-controlled design. Creatine supplementation included 0.3 g/kg/day for 14 days, caffeine supplementation included 0.3 mg/kg per day, and pre-activation in HBS with I-sVR (1 × 5 at 30% 1RM [1.0-1.1 m/s] + 1 × 4 at 60% 1RM [0.6-0.7 m/s]). The RSA test and HBS outcomes were evaluated. Three-way ANOVA showed non-significant differences for the RSA test and HBS outcomes (p > 0.05). At the end of this study, it was found that the three ergogenic aids, together, do not generate a summative effect on the physical performance of young soccer players. However, it is important to analyze individual responses to these specific protocols.

Effects of Different Caffeine Dosages on Maximal Physical Performance and Potential Side Effects in Low-Consumer Female Athletes: Morning vs. Evening Administration.

While previous studies have explored a range of factors governing the optimal use of caffeine (CAF) in athletes, limited research has explored how time of day (TOD) affects the ergogenic effects of various CAF dosages on physical performance. This study aimed to increase knowledge about how different recommended CAF doses (3 mg/kg vs. 6 mg/kg) ingested at different TODs affected maximal high-intensity physical performance and the perception of potential side effects in female athletes. In this double-blind, randomized, and counterbalanced study, 15 low CAF consumer athletes (aged 18.3 ± 0.5 y) underwent six trials, including three testing conditions assessed across two TODs: one in the morning (08:00 a.m.) and one in the evening (06:00 p.m.). During each condition, the participants ingested either a placebo, 3 mg/kg CAF (CAF (3 mg)), or 6 mg/kg CAF (CAF (6 mg)) capsules 60 min before each test with an in-between washout period of at least 72 h. In each trial, the participants performed a countermovement jumps test (CMJ), a modified agility t test (MATT), a repeated sprint ability (RSA), a rating of perceived exertion (RPE), and finally, a CAF side effects questionnaire. Our findings indicate the absence of an ergogenic effect on CMJ, MAT, and RSA performance in the evening after administering CAF (3 mg) or CAF (6 mg) compared to a placebo. Likewise, when CAF was ingested in the morning, there was an improvement in these performances with both CAF (3 mg) and CAF (6 mg), with greater improvement observed after CAF (6 mg). Additionally, neither the CAF dosage nor the TOD had a significant effect on the RPE. The occurrence of side effects increased significantly after the evening ingestion of CAF, particularly with a moderate dose of CAF (6 mg). Our findings indicate that the effectiveness of CAF depends on the TOD and CAF dosage. When ingested in the morning, a moderate dose of CAF (6 mg), rather than CAF (3 mg), is more effective in improving short-term physical performance without affecting CAF side effects in female athletes. Nevertheless, when ingested in the evening, neither dose was sufficient to enhance short-term physical performance, and both dosages increased the incidence of CAF side effects, particularly at a moderate dose.

Profiling and assessing the risks of image- and performance-enhancing drugs use during the COVID-19 lockdown.

Background: Image and Performance-Enhancing Drugs (IPEDs) can enhance mental and physical capabilities and impact one's overall health. Initially confined in sport environments, IPEDs use has become increasingly widespread in a high-performing society. The present study was aimed at profiling IPEDs use during the COVID-19 lockdown among an international sample of young adults. Methods: A cross-sectional observational study was carried out in eight countries (United Kingdom, Italy, Lithuania, Hungary, Portugal, Spain, Brazil, and Japan) between April and May 2020. The survey questionnaire included validated measurements such as Exercise Addiction Inventory (EAI), Appearance Anxiety Inventory (AAI), and Self-Compassion Scale (SCS) as well as questions about the type of IPEDs, purchasing methods and socio-demographic information. Results: A total of 736 IPEDs users were included in the survey. Their mean age was 33.05 years (±SD = 10.06), and 64.2% were female participants. Overall, 6.8% were found at risk of exercise addiction (EAI >24), 27.6% presented high levels of appearance anxiety, and 24.9% revealed low levels of emotional regulation's self-compassion. Most participants (55.6%) purchased IPEDs through pharmacies/specialized shops, while 41.3% purchased IPEDs on the Internet. Online IPEDs buyers were mainly men who had higher scores on the Exercise Addiction Inventory. One or more IPEDs classifiable as "potentially risky" were used by 66.3% of the sample. Users of "potentially risky IPEDs" were younger and primarily men. They showed higher scores both on the Exercise Addiction Inventory and Appearance Anxiety Inventory. Conclusion: This study profiled users of IPEDs when the most restrictive COVID-19 lockdown policies were implemented in all the participating countries. More targeted post-COVID 19 prevention strategies should be implemented according to the emerged socio-demographic and psychopathological traits and cross-cultural differences emerged. Longitudinal studies will also be needed to determine the long-term effect of the COVID-19 lockdown on IPEDs consumption.

Caffeine Boosts Weight-Lifting Performance in Rats: A Pilot Study.

Caffeine is a well-described ergogenic aid used to enhance athletic performance. Using animal models can greatly increase our understanding of caffeine's mechanisms in performance. Here, we adapted an animal weight-lifting exercise model to demonstrate caffeine's ergogenic effect in rats. Male Wistar rats (315 ± 35 g) were randomly divided into two groups: one group received 5 mg·kg-1 of caffeine (0.5 mL; CEx; n = 5) and the other 0.9% NaCl (0.5 mL; PEx; n = 4) through an orogastric probe (gavage) one hour before exercise. Weight-lifting exercise sessions were performed over three subsequent days, and the number of complete squats performed was counted. Analyses of the area under the curve in all three experiments showed that the CEx group responded more to stimuli, performing more squats (1.7-, 2.0-, and 1.6-fold; p < 0.05) than the control group did. These three days' data were analyzed to better understand the cumulative effect of this exercise, and a hyperbolic curve was fitted to these data. Data fitting from the caffeine-supplemented group, CEx, also showed larger Smax and Kd (2.3-fold and 1.6-fold, respectively) than the PEx group did. Our study demonstrated an acute ergogenic effect of caffeine in an animal weight-lifting exercise model for the first time, suggesting potential avenues for future research.

Echinacea Supplementation Does Not Impact Aerobic Capacity and Erythropoiesis in Athletes: A Meta-Analysis.

Athletes are increasingly relying on natural supplements to improve athletic performance. Echinacea, a common herbal supplement, has been studied for its potential erythropoietin-enhancing effects, with mixed results in the literature. The purpose of this meta-analysis is to determine whether echinacea supplementation has erythropoietic or ergogenic effects in athletes. A search strategy was developed to identify trials studying the impact of echinacea supplementation on erythropoiesis and maximal oxygen uptake. The database search yielded 502 studies, 496 of which were excluded in the two-reviewer screening process. Six studies with a total of 107 athletes were included in the analysis. For hemoglobin and hematocrit levels, there were small, positive effect sizes when comparing the difference in pre- and post-intervention levels between the echinacea and placebo groups, at 0.38 (p = 0.02, 95% CI -0.04-0.80, I2 = 70%) and 0.34 (p < 0.01, 95% CI -0.10-0.78, I2 = 86%), respectively, though they did not reach statistical significance. There was also no statistically significant change in erythropoietin (effect size -0.29, p = 0.05, 95% CI -0.75-0.17, I2 = 67%) or maximal oxygen uptake (effect size -0.20, p = 0.95, 95% CI -0.60-0.21, I2 = 0%). Echinacea supplementation did not influence erythropoietin, hemoglobin, hematocrit, or maximal oxygen uptake in athletes; however, the evidence base is limited.

Sex Differences in the Ergogenic Response of Acute Caffeine Intake on Muscular Strength, Power and Endurance Performance in Resistance-Trained Individuals: A Randomized Controlled Trial.

BACKGROUND: This study assessed the impact of acute caffeine intake on muscular strength, power, and endurance performance between resistance-trained male and female individuals according to load in upper- and lower-body exercises. METHODS: Here, 76 resistance-trained individuals (38 females, 38 males) participated in a study comparing caffeine and a placebo. Each received either 3 mg/kg of caffeine or a placebo 60 min before tests measuring muscular strength and power through bench press and back squat exercises at different intensities (25%, 50%, 75%, 90% 1RM). Muscular endurance at 65% 1RM was also assessed by performing reps until reaching task failure. RESULTS: Compared to placebo, caffeine increased mean, peak and time to reach peak velocity and power output (p < 0.01, ηp2 = 0.242-0.293) in the muscular strength/power test in males and females. This effect was particularly observed in the back squat exercise at 50%, 75% and 90% 1RM (2.5-8.5%, p < 0.05, g = 1.0-2.4). For muscular endurance, caffeine increased the number of repetitions, mean velocity and power output (p < 0.001, ηp2 = 0.177-0.255) in both sexes and exercises (3.0-8.9%, p < 0.05, g = 0.15-0.33). CONCLUSIONS: Acute caffeine intake resulted in a similar ergogenic effect on muscular strength, power, and endurance performance in upper- and lower-body exercises for male and female resistance-trained participants.

Nutritional Ergogenic Aids in Cycling: A Systematic Review.

This systematic review aimed to evaluate the effectiveness of the independent or combined use of nutritional ergogenic aids belonging to Group A of the ABCD classification by the Australian Institute of Sport (AIS) in the context of cycling (caffeine, creatine, sodium bicarbonate, beta-alanine, nitrates, and glycerol). A comprehensive search was carried out using three databases: PubMed, Scopus, and Web of Science. All the databases were searched for Randomized Controlled Trials or crossover design studies assessing the effects of supplementation on cycling performance in comparison with placebos in healthy adults. The methodological quality of each study was evaluated using the Physiotherapy Evidence Database scale. Thirty-six articles involving 701 participants were included in this review, examining supplementation with caffeine (n = 5), creatine (n = 2), sodium bicarbonate (n = 6), beta-alanine (n = 3), and nitrates (n = 8). Additionally, supplemental combinations of caffeine and creatine (n = 3), caffeine and sodium bicarbonate (n = 3), caffeine and nitrates (n = 1), creatine and sodium bicarbonate (n = 1), and sodium bicarbonate and beta-alanine (n = 4) were analyzed. A benefit for cyclists' athletic performnce was found when consuming a caffeine supplement, and a potential positive effect was noted after the consumption of sodium bicarbonate, as well as after the combination of caffeine and creatine. However, no statistically significant effects were identified for the remaining supplements, whether administered individually or in combination.

Effect of caffeine ingestion on time trial performance in cyclists: a systematic review and meta-analysis.

BACKGROUND: Caffeine, widely recognized as an ergogenic aid, has undergone extensive research, demonstrating its effectiveness to enhance endurance performance. However, there remains a significant gap in systematically evaluating its effects on time trial (TT) performance in cyclists. PURPOSE: This meta-analysis aimed to determine the efficacy of caffeine ingestion to increase cycling TT performance in cyclists and to evaluate the optimal dosage range for maximum effect. METHODS: A search of four databases was completed on 1 December 2023. The selected studies comprised crossover, placebo-controlled investigations into the effects of caffeine ingestion on cycling TT performance. Completion time (Time) and mean power output (MPO) were used as performance measures for TT. Meta-analyses were performed using a random-effects model to assess the standardized mean differences (SMD) in individual studies. RESULTS: Fifteen studies met the inclusion criteria for the meta-analyses. Subgroup analysis showed that moderate doses of caffeine intake (4-6 mg/kg) significantly improved cycling performance (SMD Time = -0.55, 95% confidence interval (CI) = -0.84 ~ -0.26, p < 0.01, I2 = 35%; SMD MPO = 0.44, 95% CI = 0.09 ~ 0.79, p < 0.05, I2 = 39%), while the effects of low doses (1-3 mg/kg) of caffeine were not significant (SMD Time = -0.34, 95% CI = -0.84 ~ 0.17, p = 0.19, I2 = 0%; SMD MPO = 0.31, 95% CI = -0.02 ~ 0.65, p = 0.07, I2 = 0%). CONCLUSION: A moderate dosage (4-6 mg/kg) of caffeine, identified as the optimal dose range, can significantly improve the time trial performance of cyclists, while a low dose (1-3 mg/kg) does not yield improvement. In addition, the improvements in completion time and mean power output resulting from a moderate dose of caffeine are essentially the same in cycling time trails.

Active ischemic pre-conditioning does not additively improve short-term high-intensity cycling performance when combined with caffeine ingestion in trained young men.

We investigated the effect of ischemic preconditioning (IPC) with and without caffeine supplementation on mean power output (MPO) during a 4-min cycling time-trial (TT). In a double-blinded, randomized, crossover-design, 11 trained men performed a TT on 4 days separated by ∼1 week. One hour before TT, participants ingested either caffeine (3 mg kg bw-1) or placebo pills, after which femoral blood-flow was either restricted with occlusion cuffs inflated to ∼180 mmHg (IPC), or sham-restricted (0-10 mmHg; Sham) during 3 × 2-min low-intensity cycling (10% of incremental peak power output). Then, participants performed a standardized warm-up followed by the TT. Plasma lactate and K+ concentrations and ratings of perceived exertion (RPE) were measured throughout trials. TT MPO was 382 ± 17 W in Placebo + Sham and not different from Placebo + IPC (-1 W; 95% CI: -9 to 7; p = 0.848; d: 0.06), whereas MPO was higher with Caffeine + Sham (+6W; 95% CI: -2 to 14; p = 0.115; d: 0.49) and Caffeine + IPC (+8 W; 95% CI: 2-13; p = 0.019; d: 0.79) versus Placebo + Sham. MPO differences were attributed to caffeine (caffeine main-effect: +7 W; 95% CI: 2-13; p = 0.015; d: 0.54. IPC main-effect: 0 W; 95% CI: -6 to 7; p = 0.891; d: 0.03; caffeine × IPC interaction-effect: p = 0.580; d: 0.17). TT RPE and plasma variables were not different between treatments. In conlcusion, IPC with co-ingestion of placebo does not improve short-term high-intensity performance in trained men versus a double-placebo control (Placebo + Sham) and does not additively enhance performance with caffeine. These data do not support IPC as a useful strategy for athletes prior to competition but confirms caffeine's performance-enhancing effect.

Effects of 3 days of citrulline malate supplementation on short-duration repeated sprint running performance in male team sport athletes.

Citrulline malate (CM) is purported to be an ergogenic aid during various types of exercise performance. However, the effects of CM on repeated sprint performance (RSP) are under-explored. In a placebo-controlled, double-blind, counterbalanced cross-over design, male university-level team sport athletes (n = 13) performed two familiarization trials, after which CM or placebo (PLA) (8 × 1 g tablets each day) were taken on the 2 days prior to, and with breakfast on the morning of, each main experimental trial. The main experimental trials employed a RSP protocol consisting of 10 repetitions of 40 m maximal shuttle run test (MST) with a 30 s interval between the start of each sprint. Sprint times and heart rate were recorded throughout the MST, and blood lactate concentrations were measured before, immediately after, and 5 min after completing the MST. CM resulted in better RSP compared to PLA, as indicated by a lower sprint performance decrement (Sdec: CM, 4.68% ± 1.82% vs. PLA, 6.10% ± 1.83%; p = 0.03; ES = 0.77), which was possibly influenced by the fastest sprint time being faster in CM (CM, 8.16 ± 0.34 s vs. PLA, 8.29 ± 0.39 s; p = 0.011; ES = 0.34). There were no differences between CM and PLA in average sprint time (p = 0.54), slowest sprint time (p = 0.48), blood lactate concentrations (p = 0.73) or heart rate (p = 0.18), nor was there a condition × time interaction effect across the 10 sprints (p = 0.166). Three days of CM supplementation (8 g daily) attenuated the sprint performance decrement during short-duration high-intensity exercise in the form of running RSP in male university-level team sport athletes.

ACE gene polymorphisms (rs4340) II and DI are more responsive to the ergogenic effect of caffeine than DD on aerobic power, heart rate, and perceived exertion in a homogeneous Brazilian group of adolescent athletes.

The purpose of this study was to verify the association between angiotensin-converting enzyme (ACE) genotypes DD, DI, and II and caffeine (CAF) ingestion on endurance performance, heart rate, ratio of perceived exertion (RPE), and habitual caffeine intake (HCI) of adolescent athletes. Seventy-four male adolescent athletes (age: DD=16±1.7; DI=16±2.0; II=15±1.7 years) ingested CAF (6 mg/kg) or placebo (PLA) one hour before performing the Yo-Yo Intermittent Recovery level 1 (Yo-Yo IR1) test. No difference was found among groups for HCI. However, CAF increased the maximal distance covered and VO2max in DI and II genotype carriers compared to PLA (DD: Δ=31 m and 0.3 mL·kg-1·min-1; DI: Δ=286 m and 1.1 mL·kg-1·min-1; II: Δ=160 m and 1.4 mL·kg-1·min-1). Heart rate of DI and II genotype carriers increased with CAF compared to PLA, while RPE was higher in the II and lower in the DD genotypes. The correlations between HCI and maximal distance covered or VO2max were significant in the II genotype carriers with CAF. CAF increased endurance capacity, heart rate, and RPE in adolescent athletes with allele I, while endurance performance and aerobic power had a positive correlation to HCI in the II genotype group. These findings suggested that DD genotype were less responsive to CAF and that genetic variations should be taken into account when using CAF supplementation to enhance exercise performance.

Paraxanthine provides greater improvement in cognitive function than caffeine after performing a 10-km run.

RATIONALE: Intense exercise promotes fatigue and can impair cognitive function, particularly toward the end of competition when decision-making is often critical for success. For this reason, athletes often ingest caffeinated energy drinks prior to or during exercise to help them maintain focus, reaction time, and cognitive function during competition. However, caffeine habituation and genetic sensitivity to caffeine (CA) limit efficacy. Paraxanthine (PX) is a metabolite of caffeine reported to possess nootropic properties. This study examined whether ingestion of PX with and without CA affects pre- or post-exercise cognitive function. METHODS: 12 trained runners were randomly assigned to consume in a double-blind, randomized, and crossover manner 400 mg of a placebo (PL); 200 mg of PL + 200 mg of CA; 200 mg of PL + 200 mg of PX (ENFINITY®, Ingenious Ingredients); or 200 mg PX + 200 mg of CA (PX+CA) with a 7-14-day washout between treatments. Participants donated fasting blood samples and completed pre-supplementation (PRE) side effects questionnaires, the Berg-Wisconsin Card Sorting Test (BCST), and the Psychomotor Vigilance Task Test (PVTT). Participants then ingested the assigned treatment and rested for 60 minutes, repeated tests (PRE-EX), performed a 10-km run on a treadmill at a competition pace, and then repeated tests (POST-EX). Data were analyzed using General Linear Model (GLM) univariate analyses with repeated measures and percent changes from baseline with 95% confidence intervals. RESULTS: BCST correct responses in the PX treatment increased from PRE-EX to POST-EX (6.8% [1.5, 12.1], p = 0.012). The error rate in the PL (23.5 [-2.8, 49.8] %, p = 0.078) and CA treatment (31.5 [5.2, 57.8] %, p = 0.02) increased from PRE-EX values with POST-EX errors tending to be lower with PX treatment compared to CA (-35.7 [-72.9, 1.4] %, p = 0.059). POST-EX perseverative errors with PAR rules were significantly lower with PX treatment than with CA (-26.9 [-50.5, -3.4] %, p = 0.026). Vigilance analysis revealed a significant interaction effect in Trial #2 mean reaction time values (p = 0.049, ηp2 = 0.134, moderate to large effect) with POST-EX reaction times tending to be faster with PX and CA treatment. POST-EX mean reaction time of all trials with PX treatment was significantly faster than PL (-23.2 [-43.4, -2.4] %, p = 0.029) and PX+CA (-29.6 [-50.3, -8.80] %, p = 0.006) treatments. There was no evidence that PX ingestion adversely affected ratings of side effects associated with stimulant intake or clinical blood markers. CONCLUSIONS: Results provide some evidence that pre-exercise PX ingestion improves prefrontal cortex function, attenuates attentional decline, mitigates cognitive fatigue, and improves reaction time and vigilance. Adding CA to PX did not provide additional benefits. Therefore, PX ingestion may serve as a nootropic alternative to CA.

Timing Matters: Time of Day Impacts the Ergogenic Effects of Caffeine-A Narrative Review.

Caffeine has attracted significant attention from researchers in the sports field due to its well-documented ergogenic effects across various athletic disciplines. As research on caffeine continues to progress, there has been a growing emphasis on evaluating caffeine dosage and administration methods. However, investigations into the optimal timing of caffeine intake remain limited. Therefore, this narrative review aimed to assess the ergogenic effects of caffeine administration at different times during the morning (06:00 to 10:00) and evening (16:00 to 21:00). The review findings suggest that circadian rhythms play a substantial role in influencing sports performance, potentially contributing to a decline in morning performance. Caffeine administration has demonstrated effectiveness in mitigating this phenomenon, resulting in ergogenic effects and performance enhancement, even comparable to nighttime levels. While the specific mechanisms by which caffeine regulates circadian rhythms and influences sports performance remain unclear, this review also explores the mechanisms underlying caffeine's ergogenic effects, including the adenosine receptor blockade, increased muscle calcium release, and modulation of catecholamines. Additionally, the narrative review underscores caffeine's indirect impact on circadian rhythms by enhancing responsiveness to light-induced phase shifts. Although the precise mechanisms through which caffeine improves morning performance declines via circadian rhythm regulation necessitate further investigations, it is noteworthy that the timing of caffeine administration significantly affects its ergogenic effects during exercise. This emphasizes the importance of considering caffeine intake timing in future research endeavors to optimize its ergogenic potential and elucidate its mechanisms.

Caffeine Improves Sprint Time in Simulated Freestyle Swimming Competition but Not the Vertical Jump in Female Swimmers.

Caffeine (CAF) has been shown to be an effective ergogenic aid in enhancing sports performance, including vertical jump (VJ), sprint, balance, agility, and freestyle swimming performance (FSP). However, whether acute CAF supplementation improves FSP in moderately trained female swimmers has not been well documented. Therefore, this study aimed to investigate the effects of CAF intake on vertical jump, balance, auditory reaction time (ART), and swimming performance in female swimmers. In a double-blind, cross-over design, eight moderately trained female swimmers (age: 21.3 ± 1.4 years, height: 161.2 ± 7.1 cm, body mass: 56.3 ± 6.7 kg, body mass index (BMI): 21.9 ± 1.3 kg/m2, and habitual CAF intake: 246.4 ± 111.4 mg/day) ingested caffeine (CAF) (6 mg/kg) or a placebo (PLA) 60 min before completing VJ, balance, ART, and 25/50 m FSP. CAF supplementation resulted in a significantly lower time both in 25m (p = 0.032) and 50m (p = 0.033) FSP. However, CAF resulted in no significant difference in VJ, ART, and RPE (p > 0.05). Balance test results showed a non-significant moderate main effect (d = 0.58). In conclusion, CAF seems to reduce time in short-distance swimming performances, which could be the determinant of success considering the total time of the race. Thus, we recommend coaches and practitioners incorporate CAF into swimmers' nutrition plans before competitions, which may meet the high performance demands.

Comprehensive analysis of prohibited substances and methods in sports: Unveiling trends, pharmacokinetics, and WADA evolution.

This review systematically compiles sports-related drugs, substances, and methodologies based on the most frequently detected findings from prohibited lists published annually by the World Anti-Doping Agency (WADA) between 2003 and 2021. Aligned with structure of the 2023 prohibited list, it covers all proscribed items and details the pharmacokinetics and pharmacodynamics of five representatives from each section. Notably, it explores significant metabolites and metabolic pathways associated with these substances. Adverse analytical findings are summarized in tables for clarity, and the prevalence is visually represented through charts. The review includes a concise historical overview of doping and WADA's role, examining modifications in the prohibited list for an understanding of evolving anti-doping measures.

Can caffeine improve your performance? Psychophysiological effects - A systematic review.

Introduction: Caffeine is a widely used ergogenic aid in society, which has made it a topic of interest due to its various benefits at cognitive, physiological, and sports levels, among others. This review aims to investigate the potential benefits of caffeine supplementation in psychophysiological performance through a structured search in the SportsDiscus/Scopus/MEDLINE and Web of Science databases (October 2022). This review followed the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guideline, and the inclusion criteria were defined based on the PICOS model. Double-blind, randomized/semi-randomized crossover articles comparing caffeine intake with an identical placebo condition were included. Filters by age or gender of the participants were not applied. The initial search gave a result of 201 articles, which after eliminating duplicates and applying the inclusion and exclusion criteria, the final sample for this review was 8 studies. The review concluded that 3 (37.5 %) found favorable ergogenic effects, 4 (50 %) found partial effects, and 1 (12.5 %) found no effects of caffeine supplementation on variables related to psychophysiological performance. In general, both partial and negative results could be linked to insufficient doses to produce any change, likewise, habitual caffeine consumption is also a variable that could be attenuating its potential ergogenic effect. In conclusion, moderate doses of caffeine 3-6 mg/kg seem to be an effective strategy to improve the psychophysiological response in various contexts without generating detrimental effects on performance, as long as the intervention designs consider the variables that could condition its effect.

Introducción: La cafeína es una ayuda ergogénica de amplio uso en la sociedad, lo que la ha convertido en un tema de interés por sus diversos beneficios a nivel cognitivo, fisiológico y deportivo, entre otros. Esta revisión tiene como objetivo investigar los beneficios potenciales de la suplementación de cafeína sobre el rendimiento psicofisiológico a través de una búsqueda estructurada en las bases de datos SportsDiscus/Scopus/MEDLINE y Web of Science (octubre de 2022). Esta revisión siguió la guía Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) y los criterios de inclusión se definieron en función del modelo PICOS. Se incluyeron artículos doble ciego, cruzados y aleatorizados/semialeatorizados en donde se comparó la ingesta de cafeína con una condición idéntica de placebo. No se aplicaron filtros por edad ni sexo de los participantes. La búsqueda inicial dio un resultado de 201 artículos, los cuales, después de eliminar los duplicados y aplicar los criterios de inclusión y exclusión, dieron una muestra final para esta revisión de 8 estudios. La revisión concluyo que 3 (37,5 %) encontraron efectos ergogénicos favorables, 4 (50 %) encontraron efectos parciales y 1 (12,5 %) no encontró efectos de la suplementación de cafeína sobre las variables relacionadas con el rendimiento psicofisiológico. En general, los resultados tanto parciales como negativos podrían estar ligados a dosis insuficientes para producir algún cambio; de igual forma, el consumo habitual de cafeína también es una variable que podría estar atenuando su potencial efecto ergogénico. En conclusión, dosis moderadas de cafeína de 3-6 mg/kg parecen ser una estrategia eficaz para mejorar la respuesta psicofisiológica en diversos contextos, sin generar efectos perjudiciales en el rendimiento, siempre y cuando los diseños de intervención consideren las variables que podrían condicionar su efecto.