The effect of caffeine on cognitive performance is influenced by CYP1A2 but not ADORA2A genotype, yet neither genotype affects exercise performance in healthy adults

Habitual caffeine intake, genetics and cognitive performance

BACKGROUND

Research on caffeine and cognitive performance remains controversial. Variations in genes associated with caffeine metabolism and response such as CYP1A2, AHR and ADORA2A may account for variable findings.

AIM

To investigate caffeine × gene interactions on cognitive performance in all key domains of cognition in healthy individuals.

METHODS

Participants completed a lifestyle and food frequency questionnaire and a cognitive test battery including validated tasks to assess the domains of social cognition, memory, attention and executive function. Genotyping was performed for AHR rs6968554, CYP1A2 rs2472297, ADORA2A rs5751876, ADA rs73598374 and APOE rs429358 and rs7412.

RESULTS

Significant gene × caffeine interactions were observed for the domains of social cognition, (F2, 123 = 5.848, p = 0.004) and executive function (F2, 109 = 3.690, p = 0.028). 'Slow' metabolisers had a higher performance in social cognition compared with 'fast' metabolisers among high-caffeine consumers (p = 0.004), while 'fast' metabolisers had a higher performance in executive function compared with 'slow' metabolisers among moderate caffeine consumers (p = 0.002).

CONCLUSIONS

The present findings suggest an association between genetic caffeine metabolism, habitual caffeine intake and cognitive function in the domains of social cognition and executive function. More research in naturalistic environments using larger cohorts is needed to confirm these findings to add to our understanding of how habitual caffeine may influence cognitive function based on individual genotype.

Influence of acute and chronic therapeutic cooling on cognitive performance and well-being

PURPOSE

Research regarding the effect cold-water immersion (CWI) has on cognitive performance often uses excessive cooling protocols (>1-hour) to measure the detrimental impact prolonged cold exposure has on cognition. Previous studies have not considered shorter CWI protocols, similar to that used in recovery and wellness practices (∼10 min).

AIMS

To investigate a more ecologically valid CWI protocol on cognition, well-being and sleep in an acute and chronic manner. It was hypothesised that a therapeutic CWI protocol would improve well-being, and sleep and have no detrimental effect on cognition.

METHODS

Thirteen healthy participants (20.85±2.15 years), (169.96±7.77 cm), (72.03±14.92 kg), (27.67±9.55 BF%) volunteered to complete a 4-week CWI protocol. Participants were immersed in cold water (10.42±0.59 °C) 3-times a week for 4-weeks. Cognitive performance (Stroop & TMT), well-being (WEMWBS, PSWQ, GAD-7, SHS) and sleep (PSQI) were measured acutely and chronically over the 4-week protocol along with thermoregulatory measures (Tsk, Tco, thermal comfort).

RESULTS

Results show that CWI had no detrimental impact on cognitive performance, with Stroop performance & well-being seeing no differences acutely or chronically. Alternatively, the trail making test showed significant improvement from baseline (TMT-A 15.17±4.81-seconds, TMT-B 39.68±15.12-seconds) to week-3 (TMT-A 11.06±3.29-seconds, TMT-B 26.18±10.23-seconds). A reduction in sleep disturbances was seen from baseline scores of 7.85±3.44 AU to the end of week-3 measures 5.75±3.77 AU.

CONCLUSION

Therapeutic cooling can improve sleep quality when utilised in short frequent doses (3 times per week, for 4-weeks) and is not detrimental to cognitive performance, improving certain aspects of executive function.

The dose-dependent effect of caffeine supplementation on performance, reaction time and postural stability in CrossFit - a randomized placebo-controlled crossover trial

BACKGROUND

Caffeine (CAF) ingestion improves performance in a broad range of exercise tasks. Nevertheless, the CAF-induced, dose-dependent effect on discipline-specific performance and cognitive functions in CrossFit/High-Intensity Functional Training (HIFT) has not been sufficiently investigated. The aim of this study was to evaluate the effect of acute supplementation of three different doses of CAF and placebo (PLA) on specific performance, reaction time (RTime), postural stability (PStab), heart rate (HR) and perceived exertion (RPE).

METHODS

In a randomized double-blind placebo-controlled crossover design, acute pre-exercise supplementation with CAF (3, 6, or 9 mg/kg body mass (BM)) and PLA in 26 moderately trained CrossFit practitioners was examined. The study protocol involved five separate testing sessions using the Fight Gone Bad test (FGB) as the exercise performance evaluation and biochemical analyses, HR and RPE monitoring, as well as the assessment of RTime and PStab, with regard to CYP1A2 (rs762551) and ADORA2A (rs5751876) single nucleotide polymorphism (SNP).

RESULTS

Supplementation of 6 mgCAF/kgBM induced clinically noticeable improvements in FGBTotal results, RTime and pre-exercise motor time. Nevertheless, there were no significant differences between any CAF doses and PLA in FGBTotal, HRmax, HRmean, RPE, pre/post-exercise RTime, PStab variables or pyruvate concentrations. Lactate concentration was higher (p < 0.05) before and after exercise in all CAF doses than in PLA. There was no effect of CYP1A2 or ADORA2A SNPs on performance.

CONCLUSIONS

The dose-dependent effect of CAF supplementation appears to be limited to statistically nonsignificant but clinically considered changes on specific performance, RTime, PStab, RPE or HR. However, regarding practical CAF-induced performance implications in CrossFit/HIFT, 6 mgCAF/kgBM may be supposed as the most rational supplementation strategy.

Towards Precision Sports Nutrition for Endurance Athletes: A Scoping Review of Application of Omics and Wearables Technologies

BACKGROUND

Endurance athletes require tailored nutrition strategies to optimize performance, recovery, and training adaptations. While traditional sports nutrition guidelines provide a foundational framework, individual variability in metabolic responses underscores the need for precision nutrition, informed by genetic, biological, and environmental factors. This scoping review evaluates the application of systems biology-driven sports nutrition for endurance athletes, focusing on 'omics' and wearable technologies.

METHODS

A scoping review of the literature was conducted in PubMed, Scopus, and Web of Science in accordance with the PRISMA-ScR checklist. Research questions, search strategies, and eligibility criteria were guided by the Population-Concept-Context framework with the following inclusion criteria: original research in English, involving endurance athletes, systems biology approaches, and nutritional interventions or continuous glucose monitoring (CGM).

RESULTS

Fifty-two studies were included, with distance runners as the most studied cohort. Eleven studies used metagenomics, eleven CGM, ten nutrigenetics, ten metabolomics, seven multi-omics, one proteomics, one epigenomics, and one lipidomics. Over half (n = 31; 60%) were randomized controlled trials (RCTs) with generally high methodological quality.

CONCLUSIONS

Most studies were proof-of-concept investigations aimed at assessing biomarkers; however, the evidence linking these biomarkers to performance, recovery, and long-term health outcomes in endurance athletes remains insufficient. Future research should focus on well-powered replicated crossover RCTs, multivariate N-of-1 clinical trials, 360-degree systems-wide approaches, and the validation of genetic impacts on nutritional interventions to refine dietary guidelines.

Influence of the CYP1A2 c.-163 A > C polymorphism in the effect of caffeine on fat oxidation during exercise: a pilot randomized, double-blind, crossover, placebo-controlled trial

PURPOSE

The aim of this study was to determine the influence of the CYP1A2 c.-163 A > C (rs762551) polymorphism on the effect of oral caffeine intake on fat oxidation during exercise.

METHODS

Using a pilot randomized, double-blind, crossover, placebo-controlled trial, 32 young and healthy individuals (women = 14, men = 18) performed an incremental test on a cycle ergometer with 3-min stages at workloads from 30 to 70% of maximal oxygen uptake (VO2max). Participants performed this test after the ingestion of (a) placebo; (b) 3 mg/kg of caffeine; (c) 6 mg/kg of caffeine. Fat oxidation rate during exercise was measured by indirect calorimetry. The influence of the CYP1A2 c.-163 A > C polymorphism in the effect of caffeine on fat oxidation rates during exercise was established with a three-way ANOVA (substance × genotype × intensity).

RESULTS

Eight participants were genotyped as AA, 18 participants were CA heterozygotes, and 6 participants were CC. There was a main effect of substance (F = 3.348, p = 0.050) on fat oxidation rates during exercise with no genotype effect (F = 0.158, p = 0.959). The post hoc analysis revealed that, in comparison to the placebo, 3 and 6 mg/kg of caffeine increased fat oxidation at 40-50% VO2max in AA (all p < 0.050) and 50-60% VO2max in CA and CC participants (all p < 0.050).

CONCLUSION

Oral intake of 3 and 6 mg/kg of caffeine increased fat oxidation rate during aerobic exercise in individuals with AA, CA and CC genotypes. This suggests that the effect of caffeine to enhance fat oxidation during exercise is not influenced by the CYP1A2 c.-163 A > C polymorphism.

TRIAL REGISTRATION

The study was registered on clinicaltrials.gov with ID: NCT05975489.

The Effects of Caffeine on Blood Platelets and the Cardiovascular System through Adenosine Receptors

Caffeine is the most popular and widely consumed behaviourally active substance in the world. This review describes the influence of caffeine on the cardiovascular system, with a special focus on blood platelets. For many years, caffeine was thought to have a negative effect on the cardiovascular system mainly due to increasing blood pressure. However, more recent data suggest that habitual caffeine consumption may reduce the risk of cardiovascular disease and hypertension. This could be a significant finding as cardiovascular disease is the leading cause of death worldwide. Caffeine is known to inhibit A1 adenosine receptors, through which it is believed to modulate inter alia coronary blood flow, total peripheral resistance, diuresis, and heart rate. It has been shown that coffee possesses antiplatelet activity, but depending on the dose and the term of its use, caffeine may stimulate or inhibit platelet reactivity. Also, chronic exposure to caffeine may sensitize or upregulate the adenosine receptors in platelets causing increased cAMP accumulation and anti-aggregatory effects and decrease calcium levels elicited by AR agonists. The search for new, selective, and safe AR agonists is one of the new strategies for improving antiplatelet therapy involving targeting multiple pathways of platelet activation. Therefore, this review examines the AR-dependent impact of caffeine on blood platelets in the presence of adenosine receptor agonists.

Exploring the relationship between caffeine metabolism-related CYP1A2 rs762551 polymorphism and team sport athlete status and training adaptations

BACKGROUND

This study aimed to achieve a dual objective: to compare the frequencies of CYP1A2 rs762551 genotypes between team sport athletes and a control group, and to determine the association between the rs762551 polymorphism and changes in physical performance after a six-week training program among elite basketball players.

METHODS

The study encompassed an analysis of 504 individuals, comprising 320 athletes and 184 controls. For the Turkish cohort, DNA was isolated using the buccal swab method, and genotyping was conducted using the KASP technique. Performance assessments included the Yo-Yo IR2 and 30 m sprint tests. For Russian participants, DNA samples were extracted from peripheral blood, a commercial kit was used for DNA extraction, and genotyping of the rs762551 polymorphism was conducted using DNA microarray.

RESULT

Notably, a statistically significant linear decline in the prevalence of the CC genotype was observed with ascending levels of athletic achievement within team sports (sub-elite: 18.0%, elite: 8.2%, highly elite: 0%; p = 0.001). Additionally, the CA genotype was the most prevalent genotype in the highly elite group compared to controls (80.0% vs. 45.1%, p = 0.048). Furthermore, statistically significant improvements in Yo-Yo IR2 performance were noted exclusively among basketball players harboring the CA genotype (p = 0.048).

CONCLUSIONS

The study's findings indicate that the rs762551 CC genotype is a disadvantage in elite team sports, whereas the CA genotype provides an advantage in basketball performance.

Does ergogenic effect of caffeine supplementation depend on CYP1A2 genotypes? A systematic review with meta-analysis

BACKGROUND

The ergogenic effects of caffeine intake on exercise performance are well-established, even if differences exist among individuals in response to caffeine intake. The genetic variation of a specific gene, human cytochrome P450 enzyme 1A2 (CYP1A2) (rs762551), may be one reason for this difference. This systematic review and meta-analysis aimed to comprehensively evaluate the influence of CYP1A2 gene types on athletes' exercise performance after caffeine intake.

METHODS

A literature search through 4 databases (Web of Science, PubMed, Scopus, and China National Knowledge Infrastructure) was conducted until March 2023. The effect size was expressed as the weighted mean difference (WMD) by calculating fixed effects meta-analysis if heterogeneity was not significant (I2 ≤ 50% and p ≥ 0.1). Subgroup analyses were performed based on AA and AC/CC genotype of CYP1A2.

RESULTS

The final number of studies meeting the inclusion criteria was 12 (n = 666 participants). The overall analysis showed that the cycling time trial significantly improved after caffeine intake (WMD = -0.48, 95% confidence interval (95%CI): -0.83 to -0.13, p = 0.007). In subgroup analyses, acute caffeine intake improved cycling time trial only in individuals with the A allele (WMD = -0.90, 95%CI: -1.48 to -0.33, p = 0.002), but not the C allele (WMD = -0.08, 95%CI: -0.32 to 0.17, p = 0.53). Caffeine supplementation did not influence the Wingate (WMD = 8.07, 95%CI: -22.04 to 38.18, p = 0.60) or countermovement jump test (CMJ) performance (WMD = 1.17, 95%CI: -0.02 to 2.36, p = 0.05), and these outcomes were not influenced by CYP1A2 genotype.

CONCLUSION

Participants with the CYP1A2 genotype with A allele improved their cycling time trials after caffeine supplementation. However, compared to placebo, acute caffeine supplementation failed to increase the Wingate or CMJ performance, regardless of CYP1A2 genotype.

Effect of ADORA2A Gene Polymorphism and Acute Caffeine Supplementation on Hormonal Response to Resistance Exercise: A Double-Blind, Crossover, Placebo-Controlled Study

Previous studies have reported that TT genotype carriers of the adenosine A2a receptor (ADORA2A) gene rs5751876 polymorphism have better ergogenic and anti-inflammatory responses to caffeine intake compared to C allele carriers. The aim of the present study was twofold: (1) to investigate the association of the ADORA2A rs5751876 polymorphism with acute caffeine supplementation on hormonal (growth hormone and testosterone) response to resistance exercise (RE); (2) to examine the relationship between the rs5751876 polymorphism and the resting levels of growth hormone and testosterone in athletes who are light caffeine consumers. A double-blind, crossover, placebo-controlled study involving 30 resistance-trained men (age 21.7 ± 4.1) was conducted to assess the impact of caffeine supplementation on serum growth hormone (GH) and testosterone (TS) levels before, immediately after, and 15 min post-RE. One hour before engaging in resistance exercise, subjects were randomly administered 6 mg of caffeine per kg of body mass or a placebo (maltodextrin). After a 7-day washout period, the same protocol was repeated. Resting testosterone and growth hormone levels were examined in the sera of 94 elite athletes (31 females, age 21.4 ± 2.8; 63 males, age 22.9 ± 3.8). Caffeine consumption led to significantly greater increases in GH and TS in men with the TT genotype compared to C allele carriers. Furthermore, in the group of athletes, carriers of the TT genotype had significantly higher testosterone (p = 0.0125) and growth hormone (p = 0.0365) levels compared to C allele carriers. In conclusion, the ADORA2A gene rs5751876 polymorphism may modify the effect of caffeine intake on the hormonal response to exercise.

Genetics of caffeine and brain-related outcomes - a systematic review of observational studies and randomized trials

CONTEXT

Although the stimulant and anxiogenic properties of caffeine are widely accepted, research on its specific effects on the brain remains controversial. Growing evidence shows that interindividual differences in caffeine response may be partly due to variations in genes such as CYP1A2 and ADORA2A, which have been used to identify individuals as "fast" or "slow" caffeine metabolizers and as having a "high" or "low" caffeine sensitivity, respectively.

OBJECTIVE

The objective of this review was to identify, evaluate, and discuss current evidence on the associations between common genetic variants, caffeine consumption, and brain-related outcomes in humans.

DATA SOURCES

PubMed and Embase databases were searched for relevant reports based on a predetermined search strategy.

DATA EXTRACTION

Reports of observational and experimental studies on healthy adults who underwent (a) genetic analysis for polymorphisms in genes associated with caffeine metabolism and effects and (b) measurements of brain-related effects such as anxiety, insomnia, and cognitive performance associated with the consumption of caffeine (habitual intake or supplementation) were included.

DATA ANALYSIS

Of the 22 records included, 15 were randomized controlled trials, 6 were cross-sectional studies, and 1 was a genome-wide association study. The main outcomes identified were cognitive performance (n = 9), anxiety (n = 7), and sleep disturbance/insomnia (n = 6). Polymorphisms in the CYP1A2 gene were associated with cognitive function, while variations in the ADORA2A gene were associated with anxiety and sleep disturbance.

CONCLUSION

The present review has provided evidence that variability in the CYP1A2 and the ADORA2A genes may modulate the association between caffeine and brain-related outcomes. Future studies are warranted to investigate the specific polymorphisms implicated in each brain outcome, which cognitive functions are particularly related to caffeine (simple vs complex), whether there are gender differences in anxiety effects, and how habitual caffeine intake may influence the acute effects of caffeine.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42021257556.

Effects of Acute Caffeine Intake on Insulin-Like Growth Factor-1 Responses to Total Sleep Deprivation: Interactions with COMT Polymorphism - A Randomized, Crossover Study

INTRODUCTION

Genes encoding catechol-O-methyl-transferase (COMT) and adenosine A2A receptor (ADORA2A) have been shown to influence cognitive performances and responses to caffeine intake during prolonged wakefulness. The rs4680 single-nucleotide polymorphism (SNP) of COMT differentiates on memory score and circulating levels of the neurotrophic factor IGF-1. This study aimed to determine the kinetics of IGF-1, testosterone, and cortisol concentrations during prolonged wakefulness under caffeine or placebo intake in 37 healthy participants, and to analyze whether the responses are dependent on COMT rs4680 or ADORA2A rs5751876 SNPs.

METHODS

In caffeine (2.5 mg/kg, twice over 24 h) or placebo-controlled condition, blood sampling was performed at 1 h (08:00, baseline), 11 h, 13 h, 25 h (08:00 next day), 35 h, and 37 h of prolonged wakefulness, and at 08:00 after one night of recovery sleep, to assess hormonal concentrations. Genotyping was performed on blood cells.

RESULTS

Results indicated a significant increase in IGF-1 levels after 25, 35, and 37 h of prolonged wakefulness in the placebo condition, in subjects carrying the homozygous COMT A/A genotype only (expressed in absolute values [±SEM]: 118 ± 8, 121 ± 10, and 121 ± 10 vs. 105 ± 7 ng/mL for A/A, 127 ± 11, 128 ± 12, and 129 ± 13 vs. 120 ± 11 ng/mL for G/G, and 106 ± 9, 110 ± 10, and 106 ± 10 vs. 101 ± 8 ng/mL for G/A, after 25, 35, and 37 h of wakefulness versus 1 h; p < 0.05, condition X time X SNP). Acute caffeine intake exerted a COMT genotype-dependent reducing effect on IGF-1 kinetic response (104 ± 26, 107 ± 27, and 106 ± 26 vs. 100 ± 25 ng/mL for A/A genotype, at 25, 35, and 37 h of wakefulness vs. 1 h; p < 0.05 condition X time X SNP), plus on resting levels after overnight recovery (102 ± 5 vs. 113 ± 6 ng/mL) (p < 0.05, condition X SNP). Testosterone and cortisol concentrations decreased during wakefulness, and caffeine alleviated the testosterone reduction, unrelated to the COMT polymorphism. No significant main effect of the ADORA2A SNP was shown regardless of hormonal responses.

CONCLUSION

Our results indicated that the COMT polymorphism interaction is important in determining the IGF-1 neurotrophic response to sleep deprivation with caffeine intake (NCT03859882).

Caffeine and sport

Caffeine is a trimethylxanthine found in coffee and several other foods and beverages. Its stimulatory effects make it an interesting strategy to boost performance for athletic populations. Scientific evidence supports its efficacy to improve high-intensity endurance exercise, explosive and high-intensity efforts, resistance exercise, team sports and combat sports, though individual variation in the ergogenic response to caffeine exists. Supplementation can be taken in many forms including dissolved in water, via capsules, coffee, energy drinks and caffeinated gum; ingestion via capsules, dissolved in water or in caffeinated gum appear to be most effective. Variability in the exercise response following caffeine supplementation may be explained by genetic factors or habitual caffeine consumption. Caffeine is an excellent supplement for athletes looking to improve their exercise performance, though some consideration of side-effects and impact on sleep are warranted.

The effect of caffeine on exercise performance is not influenced by ADORA2A genotypes, alone or pooled with CYP1A2 genotypes, in adolescent athletes

PURPOSE

This study investigated the influence of the different genotypes of ADORA2A (1976 C > T, rs 5751876), alone or pooled with CYP1A2 (163 C > A rs 762551) genotypes, on the ergogenic effects of caffeine (CAF) on various aspects of physical performance in male adolescent athletes.

METHODS

Ninety male adolescent athletes (age = 15.5 ± 2 years) were classified according to their genotypes for 1976 C > T ADORA2A (TT homozygous or C_ADORA2A allele carriers) and 163 C > A CYP1A2 (AA homozygous or C_CYP1A2 allele carriers). Participants were further divided in four groups (1-TT_ADORA2A + AA_CYP1A2; 2-TT_ADORA2A + AC/CC_CYP1A2; 3-AA_CYP1A2 + CT/CC_ADORA2A;4-AC/CC_CYP1A2 + CT/CC_ADORA2A). Using a randomized, crossover, counterbalanced, and double-blind design, participants ingested CAF (6 mg kg^-1) or a placebo (PLA, 300 mg of cellulose) one hour before performing a sequence of physical tests: handgrip strength, agility test, countermovement jump (CMJ), Spike Jump (SJ), sit-ups, push-ups, and the Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1).

RESULTS

CAF enhanced handgrip strength (CAF: 35.0 ± 9.2 kg force; PLA: 33.5 ± 8.9 kg force; p = 0.050), CMJ height (CAF: 49.6 ± 12.3 cm; PLA: 48.3 ± 13.6 cm; p = 0.013), SJ height (CAF: 54.7 ± 13.3 cm; PLA: 53.1 ± 14.8 cm; p = 0.013), number of sit-ups (CAF: 37 ± 8; PLA: 35 ± 8; p = 0.001), and distance covered on the Yoyo IR1 test (CAF: 991.6 ± 371.0 m; PLA: 896.0 ± 311.0 m; p = 0.001), This CAF-induced improvement on exercise performance was, however, independent of genotypes groups (all p > 0.05). CAF had no effect on agility (CAF: 15.8 ± 1.2 s; PLA: 15.9 ± 1.3 s; p = 0.070) and push-up (CAF: 26.6 ± 12.0; PLA: 25.0 ± 11.0; p = 0.280) tests.

CONCLUSION

The acute caffeine intake of 6.0 mg.kg^-1 improves several aspects of physical performance, which seems to be independent of ADORA2A genotypes, alone or in combination with CYP1A2 genotypes.

Combined long-term enriched environment and caffeine supplementation improve memory function in C57Bl6 mice

Regular physical activity has been associated with healthy brain aging, reflected by beneficial effects on cognition and learning and memory. Nutritional supplements such as caffeine have been shown to act as cognitive enhancers and may possess neuroprotective properties. Interestingly, caffeine also improves athletic capabilities and is widely used by athletes because of its performance-enhancing effect, while information on potential additive beneficial effects of physical activity and caffeine on cognitive performance is scarce. In the present study, the effects of caffeine supplementation in combination with prolonged physical and cognitive stimulation in the form of the enriched environment (EE) housing for a duration of 4 months were analyzed. We demonstrate that caffeine supplementation together with prolonged environmental enrichment led to enhanced memory function, resulting in improved recognition and spatial working memory in behavioral paradigms such as the novel object recognition task or the Morris water maze in C57Bl6 wild-type mice. Mice housed under EE conditions showed increased gene expression levels of brain-derived neurotrophic factor (BDNF) in the hippocampus. The present findings underscore the potential impact of continuous physical activity in the prevention of age-related cognitive decline and may offer new options for combinatorial approaches.

Evaluation of Caffeine Ingested Timing on Endurance Performance based on CYP1A2 rs762551 Profiling in Healthy Sedentary Young Adults

Background

Caffeine is generally suggested to increase VO2max in endurance performance. Nevertheless, the response to caffeine ingestion does not seem to be uniform across individuals. Therefore, caffeine ingested timing on endurance performance based on the type of CYP1A2 single nucleotide polymorphism rs762551, that were classified as fast and slow metabolizers, need to be evaluated.

Methods

Thirty participants participated in this study. DNA was obtained from saliva samples and genotyped using polymerase chain reaction-restriction fragment length polymorphism. Each respondent completed beep tests under three treatments blindly: placebo, 4 mg/kg body mass of caffeine one hour, and two hours before test.

Results

Caffeine increased estimated VO2max in fast metabolizers (caffeine=29.39±4.79, placebo=27.33±4.02, p<0.05) and slow metabolizers (caffeine=31.25±6.19, placebo=29.17±5.32, p<0.05) in one hour before test. Caffeine also increased estimated VO2max in fast metabolizers (caffeine=28.91±4.65, placebo=27.33±4.02, p<0.05) and slow metabolizers (caffeine=32.53±6.68, placebo=29.17±5.32, p<0.05) in two hour before test. However, for slow metabolizers, the increasing was greater when caffeine was administered two hours before test (slow=3.37±2.07, fast=1.57±1.62, p<0.05).

Conclusion

Genetic variance may affect the optimal caffeine ingestion timing, sedentary individuals who want to enhance their endurance performance may ingest caffeine 1 hour before exercise for fast metabolizers and 2 hours before exercise for slow metabolizers.

Effects of Different Sources of Low-Dose Caffeine on Mood/Arousal and Cognitive Performance

In this study we investigated the effects of variously derived sources of low-dose caffeine on mood/arousal and cognitive performance. Twenty-two participants (15 men, 7 women; M age: 28.2, SD = 9.0 years) undertook five randomized, crossover trials in which they consumed either a water control (CON) or 80 mg of caffeine from one of four sources (coffee [COF], energy drink [END], capsule [CAP], and dissolvable mouth strip [STR]). We measured the participants' perceived efficacy of these varied caffeine sources pre-treatment; and we measured mood/arousal at pre-treatment, and again at 15 and 45 minutes post-treatment. We also measured choice reaction-time at 15 and 45 minutes post-treatment, and participants completed the psychomotor vigilance task (PVT) 45 minutes post-treatment. Caffeine increased participant ratings of alertness and decreased their ratings of tiredness irrespective of source (p's < .05), and all sources of caffeine decreased reaction time on the PVT (p's < .05), with ex-Gaussian distributional analysis localizing this to the tau-parameter, indicating lower variability. However, only the COF source was associated with improved 'overall mood' (p's < .05). Participants expected to perform better on the PVT with COF compared to CON, but there were no other significant associations between source expectancy and performance. In sum, a modest dose of caffeine, regardless of source, positively impacted mood/arousal and cognitive performance, and these effects did not appear to be influenced by expectations.

Mental Performance and Sport: Caffeine and Co-consumed Bioactive Ingredients

The plant defence compound caffeine is widely consumed as a performance enhancer in a sporting context, with potential benefits expected in both physiological and psychological terms. However, although caffeine modestly but consistently improves alertness and fatigue, its effects on mental performance are largely restricted to improved attention or concentration. It has no consistent effect within other cognitive domains that are important to sporting performance, including working memory, executive function and long-term memory. Although caffeine's central nervous system effects are often attributed to blockade of the receptors for the inhibitory neuromodulator adenosine, it also inhibits a number of enzymes involved both in neurotransmission and in cellular homeostasis and signal propagation. Furthermore, it modulates the pharmacokinetics of other endogenous and exogenous bioactive molecules, in part via interactions with shared cytochrome P450 enzymes. Caffeine therefore enjoys interactive relationships with a wide range of bioactive medicinal and dietary compounds, potentially broadening, increasing, decreasing, or modulating the time course of their functional effects, or vice versa. This narrative review explores the mechanisms of action and efficacy of caffeine and the potential for combinations of caffeine and other dietary compounds to exert psychological effects in excess of those expected following caffeine alone. The review focusses on, and indeed restricted its untargeted search to, the most commonly consumed sources of caffeine: products derived from caffeine-synthesising plants that give us tea (Camellia sinensis), coffee (Coffea genus), cocoa (Theabroma cacao) and guaraná (Paullinia cupana), plus multi-component energy drinks and shots. This literature suggests relevant benefits to mental performance that exceed those associated with caffeine for multi-ingredient energy drinks/shots and several low-caffeine extracts, including high-flavanol cocoa and guarana. However, there is a general lack of research conducted in such a way as to disentangle the relative contributions of the component parts of these products.

Does Single or Combined Caffeine and Taurine Supplementation Improve Athletic and Cognitive Performance without Affecting Fatigue Level in Elite Boxers? A Double-Blind, Placebo-Controlled Study

In previous studies, the effect of single or combined intake of caffeine (CAF) and taurine (TAU) on exercise performance was investigated. However, the potential synergistic effect on physical and cognitive performance after fatigue induced by anaerobic exercise is unknown. The effects of single and combination CAF and TAU supplementation on the Wingate test in elite male boxers and to evaluate balance, agility and cognitive performance after fatigue are being investigated for the first time in this study. Twenty elite male boxers 22.14 ± 1.42 years old were divided into four groups in this double-blind, randomized crossover study: CAF (6 mg/kg of caffeine), TAU (3 g single dose of taurine), CAF*TAU (co-ingestion of 3 g single dose of taurine and 6 mg/kg of caffeine) and PLA (300 mg maltodextrin). The findings are as follows: co-ingestion of CAF*TAU, improved peak (W/kg), average (W), minimum (W) power, time to reach (s), and RPE performances compared to the PLA group significantly (p < 0.05). Similarly, it was determined that a single dose of TAU, created a significant difference (p < 0.05) in peak power (W/kg), and average and minimum power (W) values compared to the CAF group. According to the balance and agility tests performed after the Wingate test, co-ingestion of CAF*TAU revealed a significant difference (p < 0.05) compared to the PLA group. In terms of cognitive performance, co-ingestion of CAF*TAU significantly improved the neutral reaction time (ms) compared to the TAU, CAF and PLA groups. As a result, elite male boxers performed better in terms of agility, balance and cognitive function when they consumed a combination of 6 mg/kg CAF and 3 g TAU. It has been determined that the combined use of these supplements is more effective than their single use.

Effects of Acute Ashwagandha Ingestion on Cognitive Function

BACKGROUND

Ashwagandha (Withania somnifera) has been reported to decrease perceptions of stress, enhance mood, and improve cognitive function. However, it is currently unknown whether acute ashwagandha supplementation affects memory and cognitive function. This study evaluated the effects of acute ashwagandha extract ingestion on executive function.

MATERIALS AND METHODS

13 healthy volunteers were administered the Berg-Wisconsin Card Sorting (BCST), Go/No-Go (GNG), Sternberg Task (STT), and Psychomotor Vigilance Task (PVTT) tests. Participants then ingested in a double-blind, placebo-controlled, and crossover manner 400 mg of a placebo (PLA) or ashwagandha (ASH) extract (NooGandha^®, Specnova Inc., Boca Raton, FL, USA). Participants then performed cognitive function tests every hour for 6 h. After a 4-day washout period, volunteers repeated the experiment while receiving the remaining supplement. Data were analyzed by repeated measures General Linear Model multivariate and univariate statistics with body weight as a covariate.

RESULTS

Acute ASH supplementation increased STT-determined working memory as demonstrated by an improvement in 6 letter length, Present Reaction Time at 3 and 6 h. PVTT analysis revealed that ASH sustained attention by helping maintain reaction times, preventing mental fatigue, and remaining vigilant. Conversely, reaction times (at task 20, hour 6; overall, hour 3) increased with PLA. In the BCST, there was evidence that ASH increased the ability to recognize and 'shift' to a new rule compared with baseline. However, this was not seen when evaluating changes from baseline, suggesting that differences in baseline values influence results. In the GNG test, ASH ingestion promoted faster response times to respond correctly than PLA, indicating less metal fatigue. However, ASH did not affect accuracy compared to PLA, as both treatments decreased the percentage of correct answers.

CONCLUSIONS

Acute supplementation with 400 mg of ashwagandha improved selected measures of executive function, helped sustain attention, and increased short-term/working memory.

Acute Paraxanthine Ingestion Improves Cognition and Short-Term Memory and Helps Sustain Attention in a Double-Blind, Placebo-Controlled, Crossover Trial

This study examined the effects of acute paraxanthine (PXN) ingestion on markers of cognition, executive function, and psychomotor vigilance. In a randomized, double blind, placebo-controlled, crossover, and counterbalanced manner, 13 healthy male and female participants were randomly assigned to consume a placebo (PLA) or 200 mg of PXN (ENFINITY™, Ingenious Ingredients, L.P.). Participants completed stimulant sensitivity and side effect questionnaires and then performed the Berg Wisconsin Card Sorting Test (BCST), the Go/No-Go test (GNG), the Sternberg task test (STT), and the psychomotor vigilance task test (PVTT). Participants then ingested one capsule of PLA or PXN treatment. Participants completed side effect and cognitive function tests after 1, 2, 3, 4, 5, and 6 h after ingestion of the supplement. After 7 days, participants repeated the experiment while consuming the alternative treatment. Data were analyzed by general linear model (GLM) univariate analyses with repeated measures using body mass as a covariate, and by assessing mean and percent changes from baseline with 95% confidence intervals (CIs) expressed as means (LL, UL). PXN decreased BCST errors (PXN −4.7 [−0.2, −9.20], p = 0.04; PXN −17.5% [−36.1, 1.0], p = 0.06) and perseverative errors (PXN −2.2 [−4.2, −0.2], p = 0.03; PXN −32.8% [−64.4, 1.2], p = 0.04) at hour 6. GNG analysis revealed some evidence that PXN ingestion better maintained mean accuracy over time and Condition R Round 2 response time (e.g., PXN −25.1 [−52.2, 1.9] ms, p = 0.07 faster than PLA at 1 h), suggesting better sustained attention. PXN ingestion improved STT two-letter length absent and present reaction times over time as well as improving six-letter length absent reaction time after 2 h (PXN −86.5 ms [−165, −7.2], p = 0.03; PXN −9.0% [−18.1, 0.2], p = 0.05), suggesting that PXN enhanced the ability to store and retrieve random information of increasing complexity from short-term memory. A moderate treatment x time effect size (η_p² = 0.08) was observed in PVTT, where PXN sustained vigilance during Trial 2 after 2 h (PXN 840 ms [103, 1576], p = 0.03) and 4 h (PXN 1466 ms [579, 2353], p = 0.002) compared to PL. As testing progressed, the response time improved during the 20 trials and over the course of the 6 h experiment in the PXN treatment, whereas it significantly increased in the PL group. The results suggest that acute PXN ingestion (200 mg) may affect some measures of short-term memory, reasoning, and response time to cognitive challenges and help sustain attention.

Caffeine as a Factor Influencing the Functioning of the Human Body-Friend or Foe?

Nowadays, caffeine is one of the most commonly consumed substances, which presents in many plants and products. It has both positive and negative effects on the human body, and its activity concerns a variety of systems including the central nervous system, immune system, digestive system, respiratory system, urinary tract, etc. These effects are dependent on quantity, the type of product in which caffeine is contained, and also on the individual differences among people (sex, age, diet etc.). The main aim of this review was to collect, present, and analyze the available information including the latest discoveries on the impact of caffeine on human health and the functioning of human body systems, taking into account the role of caffeine in individual disease entities. We present both the positive and negative sides of caffeine consumption and the healing properties of this purine alkaloid in diseases such as asthma, Parkinson's disease, and others, not forgetting about the negative effects of excess caffeine (e.g., in people with hypertension, children, adolescents, and the elderly). In summary, we can conclude, however, that caffeine has a multi-directional influence on various organs of the human body, and because of its anti-oxidative properties, it was, and still is, an interesting topic for research studies including those aimed at developing new therapeutic strategies.

Genetic Determinants of Neurobehavioral Responses to Caffeine Administration during Sleep Deprivation: A Randomized, Cross Over Study (NCT03859882)

This study investigated whether four single nucleotide polymorphisms (SNPs) moderated caffeine effects on vigilance and performance in a double-blind and crossover total sleep deprivation (TSD) protocol in 37 subjects. In caffeine (2 × 2.5 mg/kg/24 h) or placebo-controlled condition, subjects performed a psychomotor vigilance test (PVT) and reported sleepiness every six hours (Karolinska sleepiness scale (KSS)) during TSD. EEG was also analyzed during the 09:15 PVT. Carriers of the TNF-α SNP A allele appear to be more sensitive than homozygote G/G genotype to an attenuating effect of caffeine on PVT lapses during sleep deprivation only because they seem more degraded, but they do not perform better as a result. The A allele carriers of COMT were also more degraded and sensitive to caffeine than G/G genotype after 20 h of sleep deprivation, but not after 26 and 32 h. Regarding PVT reaction time, ADORA2A influences the TSD effect but not caffeine, and PER3 modulates only the caffeine effect. Higher EEG theta activity related to sleep deprivation was observed in mutated TNF-α, PER3, and COMT carriers, in the placebo condition particularly. In conclusion, there are genetic influences on neurobehavioral impairments related to TSD that appear to be attenuated by caffeine administration. (NCT03859882).

Whole Genome Interpretation for a Family of Five

Although best practices have emerged on how to analyse and interpret personal genomes, the utility of whole genome screening remains underdeveloped. A large amount of information can be gathered from various types of analyses via whole genome sequencing including pathogenicity screening, genetic risk scoring, fitness, nutrition, and pharmacogenomic analysis. We recognize different levels of confidence when assessing the validity of genetic markers and apply rigorous standards for evaluation of phenotype associations. We illustrate the application of this approach on a family of five. By applying analyses of whole genomes from different methodological perspectives, we are able to build a more comprehensive picture to assist decision making in preventative healthcare and well-being management. Our interpretation and reporting outputs provide input for a clinician to develop a healthcare plan for the individual, based on genetic and other healthcare data.

Energy Drinks and Sports Performance, Cardiovascular Risk, and Genetic Associations; Future Prospects

The consumption of energy drinks (e.g., containing caffeine and taurine) has increased over the last decade among adolescents and athletes to enhance their cognitive level and improve intellectual and athletic performance. Numerous studies have shown that drinking moderate doses of such drinks produces beneficial effects, as they considerably boost the sporting performance of elite athletes in various sports, including both endurance and explosive events. However, apart from their ergogenic effects, the regular consumption of energy drinks also increases blood pressure and consequently incites problems such as hypertension, tachycardia, and nervousness, all of which can lead to cardiovascular disorders. A potential positive correlation between genetics and the moderate consumption of energy drinks and athletic performance has recently been reported; notwithstanding, a better understanding of the genetic variants involved in metabolism is a key area for future research to optimize the dose of energy drink consumed and obtain the maximal ergogenic effect in elite sports. The aim of this literature review, therefore, is to present the results of recent studies, classifying them according to the differences in the associations between energy drinks and: (i) Athletic performance; (ii) cardiovascular risk factors while practicing sports; and (iii) genetic associations and future prospects between the consumption of energy drinks and performance.

Novel insights on caffeine supplementation, CYP1A2 genotype, physiological responses and exercise performance

Caffeine is a popular ergogenic aid due to its primary physiological effects that occur through antagonism of adenosine receptors in the central nervous system. This leads to a cascade of physiological reactions which increases focus and volition, and reduces perception of effort and pain, contributing to improved exercise performance. Substantial variability in the physiological and performance response to acute caffeine consumption is apparent, and a growing number of studies are implicating a single-nucleotide polymorphism in the CYP1A2 gene, responsible for caffeine metabolism, as a key factor that influences the acute responses to caffeine ingestion. However, existing literature regarding the influence of this polymorphism on the ergogenic effects of caffeine is controversial. Fast caffeine metabolisers (AA homozygotes) appear most likely to benefit from caffeine supplementation, although over half of studies showed no differences in the responses to caffeine between CYP1A2 genotypes, while others even showed either a possible advantage or disadvantage for C-allele carriers. Contrasting data are limited by weak study designs and small samples sizes, which did not allow separation of C-allele carriers into their sub-groups (AC and CC), and insufficient mechanistic evidence to elucidate findings. Mixed results prevent practical recommendations based upon genotype while genetic testing for CYP1A2 is also currently unwarranted. More mechanistic and applied research is required to elucidate how the CYP1A2 polymorphism might alter caffeine's ergogenic effect and the magnitude thereof, and whether CYP1A2 genotyping prior to caffeine supplementation is necessary.

Caffeine and Exercise Performance: Possible Directions for Definitive Findings

Caffeine is one of the most studied supplements in the world. Studies correlate its use to increased exercise performance in endurance activities, as well as its possible ergogenic effects for both intermittent and strength activities. Recent findings show that caffeine may increase or decrease exercise performance. These antagonist responses may occur even when using the same dosage and for individuals with the same characteristics, making it challenging to explain caffeine's impact and applicability. This review article provides an analytic look at studies involving the use of caffeine for human physical performance, and addresses factors that could influence the ergogenic effects of caffeine on different proposed activities. These factors subdivide into caffeine effects, daily habits, physiological factors, and genetic factors. Each variable has been focused on by discussions to research related to caffeine. A better understanding and control of these variables should be considered in future research into personalized nutritional strategies.

Caffeine Timing Improves Lower-Body Muscular Performance: A Randomized Trial

Little is known about the optimal time to consume caffeine prior to exercise to maximize the ergogenic benefits of the substance.

Purpose: To determine the optimal pre-exercise time interval to consume caffeine to improve lower-body muscular performance. A secondary aim was to identify the presence of any sex differences in responses to timed caffeine administration.

Methods: Healthy, resistance-trained males (n = 18; Mean±SD; Age: 25.1 ± 5.7 years; Height: 178.4 ± 7.1 cm; Body mass: 91.3 ± 13.5 kg; Percent body fat: 20.7 ± 5.2; Average caffeine consumption: 146.6 ± 100.3 mg/day) and females (n = 11; Mean ± SD; Age: 20.1 ± 1.6 years; Height: 165.0 ± 8.8 cm; Body mass: 65.8 ± 10.0 kg; Percent bodyfat: 25.8 ± 4.2; Average caffeine consumption: 111.8 ± 91.7 mg/day) participated in this investigation. In a randomized, double-blind, placebo-controlled, crossover fashion, participants consumed 6 mg·kg⁻¹ caffeine or placebo solution at three time points: 2 h prior (2H), 1 h prior (1H), or 30 min prior (30M) to exercise testing. During three visits, caffeine was randomly administered at one time point, and placebo was administered at the other two time points. During one visit, placebo was administered at all three time points. Next, participants performed isometric mid-thigh pulls (IMTP), countermovement vertical jumps (CMVJ), and isometric/isokinetic knee extensor testing (ISO/ISOK).

Results: Caffeine administered at 1H significantly improved absolute CMVJ and ISO performance relative to placebo. Mean CMVJ jump height was significantly higher during 1H compared to 30M. However, only caffeine administered at 30M significantly improved absolute measures of isokinetic performance. Analysis of the pooled caffeine conditions revealed that muscular performance was more consistently augmented by caffeine in males compared to females.

Conclusions: Pre-exercise caffeine timing significantly modulated participant responses to the substance, with 1H exerting the most consistent ergogenic benefits relative to other time points, particularly compared to 2H. Male participants were found to respond more consistently to caffeine compared to female participants. These results suggest that active individuals can maximize the ergogenic effects of caffeine by consuming the substance ~1 h prior to the point when peak muscular performance is desired.

Caffeine, exercise physiology, and time-trial performance: no effect of ADORA2A or CYP1A2 genotypes

The aim of this study was to investigate the influence of ADORA2A and CYP1A2 genotypes on the physiological and ergogenic effects of caffeine. Sixty-six male cyclists were screened for ADORA2A and CYP1A2 genotypes; with 40 taking part subsequently in a randomised, double-blind, placebo-controlled study. Trial 1 was used to establish the oxygen uptake-power output relationship and maximal oxygen uptake. In trials 2 and 3, participants ingested 5 mg·kg^-1 of caffeine or placebo 1 h before completing a submaximal incremental cycling test, followed by a time-trial (∼30 min). Relative to placebo, caffeine led to a significant reduction in time to complete the time-trial (caffeine: 29.7 ± 1.8 min; placebo: 30.8 ± 2.3 min); but there was no effect of genotype. During submaximal exercise, caffeine reduced mean heart rate by 2.9 ± 3.7 beats·min^-1, with effects dissipating as exercise intensity increased. Caffeine also significantly reduced perceived exertion by 0.5 ± 0.8, and increased blood lactate by 0.29 ± 0.42 mmol·L^-1, respiratory exchange ratio by 0.013 ± 0.032, and minute ventilation by 3.1 ± 6.8 L·min^-1. Nonetheless, there were no supplement × genotype interactions. In conclusion, caffeine influences physiological responses to submaximal exercise and improves time-trial performance irrespective of ADORA2A or CYP1A2 genotypes. Novelty: Caffeine affects physiological responses at rest and during submaximal exercise independent of ADORA2A or CYP1A2 genotypes. Variability in the effect of caffeine on time-trial performance is not explained by ADORA2A or CYP1A2 genotypes.

CYP1A2 genotype and acute ergogenic effects of caffeine intake on exercise performance: a systematic review

PURPOSE

To systematically review studies that examined the influence of the CYP1A2 -163C>A polymorphism on the ergogenic effects of caffeine and to discuss some of the reasons for the discrepancies in findings between the studies.

METHODS

This review was performed in accordance with the PRISMA guidelines. The search for studies was performed through nine databases.

RESULTS

Seventeen studies were included in the review. Based on the included studies, it seems that individuals with the AA or AC/CC genotype may experience an increase in performance following caffeine ingestion. Significant differences between genotypes were found in four studies, and all four reported a more favorable response in the AA vs. AC/CC genotype. These results suggest that if there is an actual genotype-related effect of acute caffeine supplementation, it might be in that direction. In the studies that reported such data for aerobic endurance, the findings are specific to male participants performing cycling time trials (distances of ≥ 10 km) and ingesting caffeine 60 min before exercise. For high-intensity exercise, two studies reported that genotype variations determined the response to caffeine ingestion, even though the differences were either small (~ 1 additional repetition in high-load resistance exercise set performed to muscular failure) or inconsistent (i.e., observed only in one out of eight performance tests).

CONCLUSIONS

CYP1A2 genotype variations may modulate caffeine's ergogenic effects, but the differences between genotypes were small, inconsistent, or limited to specific exercise scenarios. Future studies with larger sample sizes are needed to fully elucidate this research area.

Effects of CYP1A2 and ADORA2A Genotypes on the Ergogenic Response to Caffeine in Professional Handball Players

Previous investigations have found that several genes may be associated with the interindividual variability to the ergogenic response to caffeine. The aim of this study is to analyze the influence of the genetic variations in CYP1A2 (−163C  > A, rs762551; characterized such as “fast” (AA genotype) and “slow” caffeine metabolizers (C-carriers)) and ADORA2A (1976T  > C; rs5751876; characterized by “high” (TT genotype) or “low” sensitivity to caffeine (C-carriers)) on the ergogenic response to acute caffeine intake in professional handball players. Thirty-one professional handball players (sixteen men and fifteen women; daily caffeine intake = 60 ± 25 mg·d⁻¹) ingested 3 mg·kg⁻¹·body mass (bm) of caffeine or placebo 60 min before undergoing a battery of performance tests consisting of a countermovement jump (CMJ), a sprint test, an agility test, an isometric handgrip test, and several ball throws. Afterwards, the handball players performed a simulated handball match (2 × 20 min) while movements were recorded using inertial units. Saliva samples were analyzed to determine the genotype of each player for the −163C  > A polymorphism in the CYP1A2 gene (rs762551) and for the 1976T  > C polymorphism in the ADORA2A gene (rs5751876). In the CYP1A2, C-allele carriers (54.8%) were compared to AA homozygotes (45.2%). In the ADORA2A, C-allele carriers (80.6%) were compared to TT homozygotes (19.4%). There was only a genotype x treatment interaction for the ball throwing from 7 m (p = 0.037) indicating that the ergogenic effect of caffeine on this test was higher in CYP1A2 AA homozygotes than in C-allele carriers. In the remaining variables, there were no genotype x treatment interactions for CYP1A2 or for ADORA2A. As a whole group, caffeine increased CMJ height, performance in the sprint velocity test, and ball throwing velocity from 9 m (2.8–4.3%, p = 0.001–0.022, effect size = 0.17–0.31). Thus, pre-exercise caffeine supplementation at a dose of 3 mg·kg⁻¹·bm can be considered as an ergogenic strategy to enhance some neuromuscular aspects of handball performance in professional handball players with low daily caffeine consumption. However, the ergogenic response to acute caffeine intake was not modulated by CYP1A2 or ADORA2A genotypes.