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Caffeine, widely used as an ergogenic aid, has been extensively studied regarding its dosage and timing of ingestion. However, the impact of different administration methods on caffeine's performance-enhancing effects remains relatively underexplored. This study compared the effects of caffeine administered via chewing gum versus capsules on maximal strength, muscular power, and side effects during bench press and back squat exercises. Sixteen resistance-trained males participated in a double-blind, randomized trial, ingesting either a 4 mg/kg caffeine capsule (CC) or placebo capsule (PC) one hour before testing, or a 4 mg/kg caffeinated gum (CG) (4 mg/kg) or placebo gum (PG) five minutes prior. Assessments including one-repetition maximum (1RM) and muscular power at 25%, 50%, 75%, and 90%1RM for bench press and back squat. Caffeine increased 1RM (+2.1-5.0%) and muscular power (+6.1-20.0%) in both the bench press and back squat compared to placebo (all  < 0.05). However, no significant differences were observed between CC and CG for maximal strength or muscular power (all  > 0.05). Furthermore, CG was associated with fewer reports of gastrointestinal discomfort (12.5% vs. 37.5%) immediately post-exercise and tachycardia/heart palpitations (0% vs. 25.0%) at 24 hours compared to CC (all  < 0.05). Caffeinated gum (4 mg/kg) produced ergogenic effects comparable to capsules in enhancing maximal strength and muscular power during bench press and back squat exercises, with fewer side effects in resistance-trained men.

Lifestyle habits after middle age significantly impact the maintenance of cognitive function in older adults. Nutritional intake is closely related to lifestyle habits; therefore, nutrition is a pivotal factor in the prevention of dementia in the preclinical stages. Matcha green tea powder (matcha), which contains epigallocatechin gallate, theanine, and caffeine, has beneficial effects on cognitive function and mood. We conducted a randomized, double-blind, placebo-controlled clinical study over 12 months to examine the effect of matcha on cognitive function and sleep quality. Ninety-nine participants, including 64 with subjective cognitive decline and 35 with mild cognitive impairment were randomized, with 49 receiving 2 g of matcha and 50 receiving a placebo daily. Participants were stratified based on two factors: age at baseline and APOE genotype. Changes in cognitive function and sleep quality were analyzed using a mixed-effects model. Matcha consumption led to significant improvements in social acuity score (difference; -1.39, 95% confidence interval; -2.78, 0.002) (P = 0.028) as evaluated by the perception of facial emotions in cognitive function. The primary outcomes, that is, Montreal Cognitive Assessment and Alzheimer's Disease Cooperative Study Activity of Daily Living scores, showed no significant changes with matcha intervention. Meanwhile, Pittsburgh Sleep Quality Index scores indicated a trend toward improvement with a difference of 0.86 (95% confidence interval; -0.002, 1.71) (P = 0.088) between the groups in changes from baseline to 12 months. The present study suggests regular consumption of matcha could improve emotional perception and sleep quality in older adults with mild cognitive decline. Given the widespread availability and cultural acceptance of matcha green tea, incorporating it into the daily routine may offer a simple yet effective strategy for cognitive enhancement and dementia prevention.

Rationale The effect of caffeine mouth rinsing (CAF-MR) on cognitive performance has not been thoroughly investigated. Objectives To evaluate the effects of different concentrations of CAF-MR on selective attention in relation to perceived taste intensity. Methods A total of 30 healthy and recreationally active male subjects were included in this randomized, double-blind, placebo-controlled crossover trial. Interventions included MR for 20 s at rest with three different caffeine solutions (0.24% [60 mg/ 25 mL ], 0.6% [150 mg/ 25 mL ], and 1.2% [300 mg/25 mL]), MR with 25 mL water (placebo), and no MR (control). Data on Victoria Stroop Test (VST) and the perceived taste intensity were recorded at five sessions. Results CAF-MR-300 mg intervention significantly decreased completion time (from 62.93 ± 19.07 to 57.01 ± 16.74 s, p  = 0.002 in Part D), while CAF-MR-150 mg intervention significantly decreased number of errors in Part D (7.00 ± 6.21 vs. 5.63 ± 5.76, p  = 0.04) and Part C ( 8.77  ± 8.80 vs. 7.10 ± 7.11, p  = 0.02). Perceived difficulty was significantly decreased both after CAF-MR with 150 mg (5.57 ± 1.65 vs. 4.77 ± 1.98, p  = 0.006) and 300 mg (5.95 ± 1.77vs. 4.67 ± 1.96, p  < 0.001). Perceived taste intensity for 300 mg of caffeine was negatively correlated with completion time (r: ranged, 0.37 to 0.46, p ranged, 0.045 to 0.009) after 300 mg, 150 mg (p ranged, 0.04 to 0.005) and placebo (p ranged 0.044 to 0.03) interventions. Conclusions This study is the first to demonstrate that CAF-MR shows dose-dependent effects on selective attention in healthy recreational males, such as improved speed (for 300 mg caffeine), reduced error rate (for 150 mg caffeine) and decrease in perceived difficulty (for 150 and 300 mg caffeine).

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.

Purpose This study aimed to identify and describe the time course of tolerance to the most common caffeine-induced side effects. Methods Eleven participants took part in a crossover, double-blind placebo-controlled experimental design. In one phase, participants ingested 3 mg/kg/day of caffeine for 20 days, while in another phase, they ingested a placebo. Resting heart rate and blood pressure were measured three times per week during each 20-day phase and a quantitative survey was used to categorise the magnitude of side effects. Results In the pairwise comparison with the placebo, the ingestion of caffeine increased systolic (+ 7.8 ± 10.1%, P  < 0.05) and diastolic blood pressure (+ 6.4 ± 12.9% P  < 0.05) for the first 8 days of ingestion, but then this effect became attenuated for both outcomes (on day 20, − 1.1 ± 4.3% and + 0.9 ± 9.6%, respectively). The ingestion of caffeine did not affect heart rate at any time point. Caffeine increased the feelings of nervousness and vigour and the rating of gastrointestinal complaints, insomnia and diuresis at several time points in the treatment ( P  < 0.05) and they did not disappear after 20 days of ingestion. Conclusions The daily intake of 3 mg/kg of caffeine induced a meaningful elevation in arterial blood pressure that disappeared after 8 days. However, other caffeine-induced effects such as increased nervousness and vigour, irritability, insomnia and diuresis remained after 20 days of consecutive caffeine ingestion. Although there was clear tolerance to the effect of caffeine on blood pressure, the persistence of other side effects suggests the inconvenience of maintaining a chronic caffeine intake, at least at the dose of 3 mg/kg/day.

Caffeine and beta-alanine are widely used in multi-ingredient pre-workout supplements believed to enhance resistance training, but their specific role in driving this effect remains unclear. The current study employed a randomized, triple-blinded, placebo-controlled and crossover experimental design to explore the acute effects of caffeine (200 mg), beta-alanine (3 g), or their combination (200 mg caffeine and 3 g beta-alanine; C+B-A) administered 30 min prior to resistance training (RT) on mechanical, physiological, and perceptual variables. Twenty-one young resistance-trained males (age = 23.5 ± 4.5 years, body mass = 82.1 ± 10.2 kg) visited the laboratory on six occasions: one familiarization session, one preliminary testing session for load determination, and four experimental sessions which differed only in supplementation condition and involved four supersets of bench press and bench pull exercises. The supplement condition did not significantly affect any mechanical variables ( p  ≥ 0.335), except for the velocity of the last repetition of the set, where beta-alanine produced lower values (0.383 m/s) compared to placebo (0.407 m/s; p  < 0.05), with no differences observed for C+B-A (0.397 m/s) and caffeine (0.392 m/s). Heart rate was consistent across the different supplement conditions with the exception of the higher values observed immediately before the start of the RT session for placebo compared to caffeine ( p  = 0.010) and C+B-A ( p  = 0.019). Post-RT blood lactate concentration ( p  = 0.384), general and local ratings of perceived exertion ( p  = 0.177 and 0.160, respectively), and readiness ( p  = 0.281–0.925), did not differ significantly between supplement conditions. Selected supplements have minimal effects on performance and physiological responses in agonist–antagonist upper-body superset RT not leading to failure.

PurposeCaffeine is a commonly used ergogenic aid for endurance events; however, its efficacy and safety have been questioned in hot environmental conditions. The aim of this study was to investigate the effects of acute caffeine supplementation on cycling time to exhaustion and thermoregulation in the heat.MethodsIn a double-blind, randomised, cross-over trial, 12 healthy caffeine-habituated and unacclimatised males cycled to exhaustion in the heat (35 °C, 40% RH) at an intensity associated with the thermoneutral gas exchange threshold, on two separate occasions, 60 min after ingesting caffeine (5 mg/kg) or placebo (5 mg/kg).ResultsThere was no effect of caffeine supplementation on cycling time to exhaustion (TTE) (caffeine; 28.5 ± 8.3 min vs. placebo; 29.9 ± 8.8 min, P = 0.251). Caffeine increased pulmonary oxygen uptake by 7.4% (P = 0.003), heat production by 7.9% (P = 0.004), whole-body sweat rate (WBSR) by 21% (P = 0.008), evaporative heat transfer by 16.5% (P = 0.006) and decreased estimated skin blood flow by 14.1% (P < 0.001) compared to placebo. Core temperature was higher by 0.6% (P = 0.013) but thermal comfort decreased by − 18.3% (P = 0.040), in the caffeine condition, with no changes in rate of perceived exertion (P > 0.05).ConclusionThe greater heat production and storage, as indicated by a sustained increase in core temperature, corroborate previous research showing a thermogenic effect of caffeine ingestion. When exercising at the pre-determined gas exchange threshold in the heat, 5 mg/kg of caffeine did not provide a performance benefit and increased the thermal strain of participants.

There is consistent evidence supporting the ergogenic effects of caffeine for endurance based exercise. However, whether caffeine ingested through coffee has the same effects is still subject to debate. The primary aim of the study was to investigate the performance enhancing effects of caffeine and coffee using a time trial performance test, while also investigating the metabolic effects of caffeine and coffee. In a single-blind, crossover, randomised counter-balanced study design, eight trained male cyclists/triathletes (Mean ± SD: Age 41 ± 7 y, Height 1.80 ± 0.04 m, Weight 78.9 ± 4.1 kg, VO2 max 58 ± 3 ml • kg(-1) • min(-1)) completed 30 min of steady-state (SS) cycling at approximately 55% VO2max followed by a 45 min energy based target time trial (TT). One hour prior to exercise each athlete consumed drinks consisting of caffeine (5 mg CAF/kg BW), instant coffee (5 mg CAF/kg BW), instant decaffeinated coffee or placebo. The set workloads produced similar relative exercise intensities during the SS for all drinks, with no observed difference in carbohydrate or fat oxidation. Performance times during the TT were significantly faster (~5.0%) for both caffeine and coffee when compared to placebo and decaf (38.35 ± 1.53, 38.27 ± 1.80, 40.23 ± 1.98, 40.31 ± 1.22 min respectively, p<0.05). The significantly faster performance times were similar for both caffeine and coffee. Average power for caffeine and coffee during the TT was significantly greater when compared to placebo and decaf (294 ± 21 W, 291 ± 22 W, 277 ± 14 W, 276 ± 23 W respectively, p<0.05). No significant differences were observed between placebo and decaf during the TT. The present study illustrates that both caffeine (5 mg/kg/BW) and coffee (5 mg/kg/BW) consumed 1 h prior to exercise can improve endurance exercise performance.

Purpose To determine the influence of two commonly occurring genetic polymorphisms on exercise, cognitive performance, and caffeine metabolism, after caffeine ingestion. Methods Eighteen adults received caffeine or placebo (3 mg kg −1 ) in a randomised crossover study, with measures of endurance exercise (15-min cycling time trial; 70-min post-supplementation) and cognitive performance (psychomotor vigilance test; PVT; pre, 50 and 95-min post-supplementation). Serum caffeine and paraxanthine were measured (pre, 30 and 120-min post-supplementation), and polymorphisms in ADORA2A (rs5751876) and CYP1A2 (rs762551) genes analysed. Results Caffeine enhanced exercise performance ( P  < 0.001), but effects were not different between participants with ADORA2A ‘high’ ( n  = 11) vs. ‘low’ ( n  = 7) sensitivity genotype (+ 6.4 ± 5.8 vs. + 8.2 ± 6.8%), or CYP1A2 ‘fast’ ( n  = 10) vs. ‘slow’ ( n  = 8) metabolism genotype (+ 7.2 ± 5.9 vs. + 7.0 ± 6.7%, P  > 0.05). Caffeine enhanced PVT performance ( P  < 0.01). The effect of caffeine was greater for CYP1A2 ‘fast’ vs. ‘slow’ metabolisers for reaction time during exercise (− 18 ± 9 vs. − 1.0 ± 11 ms); fastest 10% reaction time at rest (− 18 ± 11 vs. − 3 ± 15 ms) and lapses at rest (− 3.8 ± 2.7 vs. + 0.4 ± 0.9) ( P  < 0.05). There were no PVT differences between ADORA2A genotypes ( P  > 0.05). Serum caffeine and paraxanthine responses were not different between genotypes ( P  > 0.05). Conclusion Caffeine enhanced CYP1A2 ‘fast’ metabolisers’ cognitive performance more than ‘slow’ metabolisers. No other between-genotype differences emerged for the effect of caffeine on exercise or cognitive performance, or metabolism.

The aim of this study was to to assess the effect of pre-exercise caffeine intake (CAF) on fatigue and recovery in basketball. Using a randomized crossover design, 14 amateur male players completed two basketball-specific training sessions (in-season phase, February–March 2024), preceded by CAF (3 mg/kg body weight) or placebo ingestion (CON). Countermovement jump height, 10- and 20-m sprint times, heart rate variability (Ln-rMSSD), static and dynamic muscle soreness, and perceived fatigue were recorded at pre-training, post-training and 24 h post-training to evaluate the effectiveness of caffeine supplementation. The results showed no significant differences between CAF and CON at corresponding time points for any variable (P > 0.05). Regarding the effect of time, the main findings indicate that countermovement jump (average percentage change [%∆] = –7% to –10%) and Ln-rMSSD (%∆ = –33% to –54%) decreased at post-training compared with all other time points (P < 0.001, effect size = 1.41–1.98), while 10-m sprint times deteriorated from pre-to-post-training (P = 0.029, effect size = 0.69, %∆ = –2%). Similarly, muscle soreness (%∆ = +171%) and perceived fatigue (%∆ = +156%) increased from pre-to-post-training in both interventions (P ≤ 0.006, r = 0.57–0.61), with static soreness in CON (%∆ = +127%) and dynamic soreness in CAF (%∆ = +139%) remaining higher than pre-training levels up to 24 h post-training (P ≤ 0.010, r = 0.53–0.58). These findings suggest that pre-exercise caffeine intake did not significantly affect markers of fatigue in amateur basketball players, either acutely or 24 h post-training. •Pre-exercise caffeine (3 mg/kg) did not affect performance or fatigue in basketball.•Caffeine did not hinder recovery, suggesting safe pre-exercise use.•Practitioners should note the limited benefits of this protocol in managing fatigue.