Acute Caffeine Supplementation Research Articles

Acute caffeine supplementation offsets the impairment in 10-km running performance following one night of partial sleep deprivation: a randomized controlled crossover trial.

Whether acute caffeine supplementation can offset the negative effects of one-night of partial sleep deprivation (PSD) on endurance exercise performance is currently unknown. Ten healthy recreational male runners (age: 27 ± 6years; : 61 ± 9mL/kg/min) completed 4 trials in a balanced Latin square design, which were PSD + caffeine (PSD-Caf), PSD + placebo (PSD-Pla), normal sleep (NS) + caffeine (NS-Caf) and NS + placebo (NS-Pla). 3 and 8h sleep windows were scheduled in PSD and NS, respectively. 10-km treadmill time trial (TT) performance was assessed 45min after caffeine (6mg/kg/body mass)/placebo supplementation in the morning following PSD/NS. Blood glucose, lactate, free fatty acid and glycerol were measured at pre-supplementation, pre-exercise and after exercise. PSD resulted in compromised TT performance compared to NS in the placebo conditions by 5% (51.9 ± 7.7 vs. 49.4 ± 6.9min, p = 0.001). Caffeine improved TT performance compared to placebo following both PSD by 7.7% (PSD-Caf: 47.9 ± 7.3min vs. PSD-Pla: 51.9 ± 7.7min, p = 0.007) and NS by 2.8% (NS-Caf: 48.0 ± 6.4min vs. NS-Pla: 49.4 ± 6.9min, p = 0.049). TT performance following PSD-Caf was not different from either NS-Pla or NS-Caf (p = 0.185 and p = 0.891, respectively). Blood glucose, lactate, and glycerol concentrations at post-exercise, as well as heart rate and the speed/RPE ratio during TT, were higher in caffeine trials compared to placebo. Caffeine supplementation offsets the negative effects of one-night PSD on 10-km running performance.

Caffeine ingestion compromises thermoregulation and does not improve cycling time to exhaustion in the heat amongst males

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.

Common questions and misconceptions about caffeine supplementation: what does the scientific evidence really show?

Caffeine is a popular ergogenic aid that has a plethora of evidence highlighting its positive effects. A Google Scholar search using the keywords "caffeine" and "exercise" yields over 200,000 results, emphasizing the extensive research on this topic. However, despite the vast amount of available data, it is intriguing that uncertainties persist regarding the effectiveness and safety of caffeine. These include but are not limited to: 1. Does caffeine dehydrate you at rest? 2. Does caffeine dehydrate you during exercise? 3. Does caffeine promote the loss of body fat? 4. Does habitual caffeine consumption influence the performance response to acute caffeine supplementation? 5. Does caffeine affect upper vs. lower body performance/strength differently? 6. Is there a relationship between caffeine and depression? 7. Can too much caffeine kill you? 8. Are there sex differences regarding caffeine's effects? 9. Does caffeine work for everyone? 10. Does caffeine cause heart problems? 11. Does caffeine promote the loss of bone mineral? 12. Should pregnant women avoid caffeine? 13. Is caffeine addictive? 14. Does waiting 1.5-2.0 hours after waking to consume caffeine help you avoid the afternoon "crash?" To answer these questions, we performed an evidence-based scientific evaluation of the literature regarding caffeine supplementation.

Acute effects of caffeine supplementation on kinematics and kinetics of sprinting.

We investigated the acute effects of caffeine supplementation (6 mg･kg-1 ) on 60-m sprint performance and underlying components with a step-to-step ground reaction force measurement in 13 male sprinters. After the first round sprint as a control, caffeine supplementation-induced improvement in 60-m sprint times (7.811 s at the first versus 7.648 s at the second round, 2.05%) were greater compared with the placebo condition (7.769 s at the first versus 7.768 s at the second round, 0.02%). Using average values for every four steps, in the caffeine condition, higher running speed (all six step groups), higher step frequency (5th-16th and 21st-24th step groups), shorter support time (all the step groups except for 13th-16th step) and shorter braking time (9th-24th step groups) were found. Regarding ground reaction forces variables, greater braking mean force (13th-19th step group), propulsive mean force (1st-12th and 17th-20th step groups), and effective vertical mean force (9th-12th step group) were found in the caffeine condition. For the block clearance phase at the sprint start, push-off and reaction times did not change, while higher total anteroposterior mean force, average horizontal external power, and ratio of force were found in the caffeine condition. These results indicate that, compared with placebo, acute caffeine supplementation improved sprint performance regardless of sprint sections during the entire acceleration phase from the start through increases in step frequency with decreases in support time. Moreover, acute caffeine supplementation promoted increases in the propulsive mean force, resulting in the improvement of sprint performance.

Caffeine Supplementation Effects on Concurrent Training Performance in Resistance-Trained Men: A Double-Blind Placebo-Controlled Crossover Study

ABSTRACT Purpose: The aim of the present study was to investigate the effects of acute caffeine supplementation on the performance during a session of resistance training alone (RT) or in combination with aerobic training (i.e. concurrent training; CT). Method: Fourteen resistance-trained men (23.1 ± 4.2 years) were recruited and performed both RT and CT under three different conditions: control (CONT), placebo (PLA), and caffeine (CAF; 6 mg.kg−1) for a total of six experimental conditions. Results: Both total and per set number of repetitions, and total volume load were lower during CT as compared to RT, irrespective of the supplementation condition (all p < .001), whereas a supplementation main effect was observed for the total number of repetitions (p = .001), the number of repetitions in the first (p = .002) and second sets (p = .001), and total volume load (p = .001). RPE values were higher after the CT sessions than after the RT sessions (p < .001), whereas no differences were observed between supplementation conditions (p = .865). Conclusions: Caffeine supplementation was not sufficient to minimize the acute interference effect on strength performance in a CT session when compared to RT alone. In contrast, caffeine improved strength performance during the first set of both CT and RT, while maintaining a similar RPE between the supplementation conditions. However, the overall effect was small.

The effects of acute caffeine supplementation on performance in trained CrossFit® athletes: A randomized, double-blind, placebo-controlled, and crossover trial

The present study aimed to evaluate the effects of caffeine on muscle strength, using a test involving one maximum repetition of the back squat, as well as on local muscular endurance. Eight trained men (mean age = 30.1 ± 6.5 years; height = 1.79 ± 0.07 meters; body mass = 81.5 ± 7.7 kg) were included in a double-blind, randomized, crossover study. The participants consumed caffeine (6 mg.kg−1) or placebo (cellulose) 60 minutes before starting the tests, with one week of washout. The participants underwent the one maximum repetition back squat test. Subsequently, they were instructed to perform the maximum number of repetitions with 60% of the maximum load to test local muscular endurance. Shapiro–Wilk and paired t-test were performed. Local muscular endurance score was higher for the caffeine group compared to placebo (3515.0 ± 1073.1 vs. 2846.5 ± 768.0 kg, P = 0.029) but not in the one maximum repetition test (156.6 ± 26.2 vs. 153.9 ± 29.5 kg, P = 0.224). The average number of repetitions were higher in the caffeine group (37.8 ± 11.1 vs. 31.4 ± 9.3 repetitions, P = 0.033). Caffeine had an ergogenic effect on CrossFit® athletes in terms of the number of repetitions, mainly when a more aerobic component (local muscular endurance) was involved; however, no effects were observed in the one maximum repetition test. La présente étude visait à évaluer les effets de la caféine sur la force musculaire, à l’aide d’un test comportant une répétition maximale du back squat, ainsi que sur l’endurance musculaire locale. Huit hommes entraînés (âge moyen = 30,1 ± 6,5 ans ; taille = 1,79 ± 0,07 mètre ; masse corporelle = 81,5 ± 7,7 kg) ont été inclus dans une étude croisée en double aveugle, randomisée. Les participants ont consommé de la caféine (6 mg.kg−1) ou du placebo (cellulose) 60 minutes avant de commencer les tests, avec une semaine de sevrage. Les participants ont subi le test de back squat à répétition maximale. Par la suite, ils ont été invités à effectuer le nombre maximum de répétitions avec 60 % de la charge maximale pour tester l’endurance musculaire locale. Un Shapiro–Wilk et un test t ont été effectués. Le score d’endurance musculaire locale était plus élevé pour le groupe caféine par rapport au placebo (3515,0 ± 1073,1 vs 2846,5 ± 768,0 kg, p = 0,029) mais pas dans le seul test de répétition maximale (156,6 ± 26,2 vs 153,9 ± 29,5 kg, p = 0,224). Le nombre moyen de répétitions était plus élevé dans le groupe caféine (37,8 ± 11,1 contre 31,4 ± 9,3 répétitions, p = 0,033). La caféine avait un effet ergogénique sur les athlètes CrossFit® en termes de nombre de répétitions, principalement lorsqu’une composante plus aérobie (endurance musculaire locale) était impliquée; cependant, aucun effet n’a été observé dans le seul test de répétition maximale.

Acute effects of caffeine supplementation on taekwondo performance: the influence of competition level and sex

The purpose of this study was to assess the effects of acute caffeine supplementation on physical performance and perceived exertion during taekwondo-specific tasks in male and female athletes with varying expertise. In a double-blinded, randomized, placebo-controlled crossover study design, 52 young athletes from elite (n = 32; 16 males and 16 females) and sub-elite competitive level (n = 20; 10 males and 10 females) participated. Athletes performed taekwondo-specific tasks including the taekwondo-specific agility test (TSAT), 10 s frequency speed of kick test (FSKT-10 s) and multi-bout FSKT (FSKT-multi) under the following conditions: (1) Caffeine (CAF; 3 mg kg−1), placebo (PLA), and no supplement control (CON). Session rating of perceived exertion (s-RPE) was determined after the tests. Findings show that regardless of condition, males performed better than females (p < 0.05) and elite athletes had superior performance compared to their sub-elite counterparts (p < 0.05). For the TSAT (p < 0.001), FSKT-10s (p < 0.001), and FSKT-multi (p < 0.001), CAF enhanced performance in elite female athletes compared to sub-elite females. Likewise, CAF ingestion resulted in superior performance in elite males compared to sub-elite males for FSKT-10s (p = 0.003) and FSKT-multi (p < 0.01). The ergogenic potential of CAF during taekwondo-specific tasks appears to be related to a competitive level, with greater benefits in elite than sub-elite athletes.

The Effect of Caffeine Supplementation on Resistance and Jumping Exercise: The Interaction with CYP1A2 and ADORA2A Genotypes

Purpose: To evaluate the association of CYP1A2 and ADORA2A gene polymorphisms, paraxanthine concentrations, and habitual caffeine (CAF) intake with respect to muscular performance after acute CAF supplementation. Methods: A total of 27 resistance-trained males participating in the study ingested either 5 mg/kg of CAF or PL 45 min before a battery of exercise tests in a cross-over design. DNA was tested for the rs5751876 and rs762551 polymorphisms. Results: CAF improved performance in jumping average power, average velocity, max velocity, bench press in the first set, and peak power in the second set. For the CYP1A2 genotype, C allele carriers improved in jumping average velocity (CAF: 1.77 ± 0.14 m/s, PL: 1.71 ± 0.16 m/s, p &lt; 0.001), and AA homozygotes improved set 1 bench press (CAF: 9.7 ± 1.7 reps, PL: 8.9 ± 1.8 reps, p = 0.046). For the ADORA2A genotype, CC (CAF: 1.70 ± 0.20 m/s, PL: 1.67 ± 0.19 m/s, p = 0.005) and CT (CAF: 1.79 ± 0.09 m/s, PL: 1.74 ± 0.11 m/s, p &lt; 0.001) improved in jumping average velocity and CT also improved in bench press set 2 peak power (CAF: 363 ± 76 W, PL: 323 ± 59 W, p = 0.021). For CAF habituation, CAF improved jumping average power (p = 0.007) and jumping average velocity (p &lt; 0.001) in high users but not in low users (p &gt; 0.05). Conclusions: CAF may improve jumping and bench press performance, irrespective of genotypes, but the associations with the genotypes in CYP1A2 and ADORA2A genes, as well as habitual CAF intake, are not clear and require further investigation.

Resistance Exercise Alone Or In Conjunction With Caffeine On Measures Of Left Ventricular Workload In Women

Resistance exercise alone or in conjunction with caffeine increases heart rate and blood pressure in resistance-trained women. While acute resistance exercise has been shown to increase measures of left ventricular workload, the addition of caffeine on these responses is unknown. PURPOSE: To evaluate alterations in left ventricular workload at rest, following acute caffeine supplementation or placebo, as well as during recovery from a fatiguing bout of resistance exercise in resistance-trained women. METHODS: Eleven resistance-trained women (Mean ± SD: Age: 24 ± 4 yrs) participated in a counterbalanced, double blind, placebo-controlled, crossover-design study. Each participant drank 4 mg/kg of caffeine mixed with water. Applanation tonometry was used to measure left ventricular workload at rest (Rest1), 45 minutes after caffeine ingestion (Rest2), immediately post-resistance exercise (Post 1), and 10 minutes post-resistance exercise (Post2). The acute bout of resistance exercise consisted of two sets at 75% 1-repetition maximum (1RM) for 10 repetitions, and one set at 70%1RM with repetitions to failure on the squat and bench press. Two minutes of rest were given between sets and exercises. A 2x4 two-way analysis of variance (ANOVA) was used to assess the effects of condition with a repeated measure of time. RESULTS: There were significant main effects of time for wasted left ventricular energy (Rest1: 608 ± 687dynes*s/cm2; Rest2: 529 ± 667dynes*s/cm2; Post1: 2154 ± 1164dynes*s/cm2; Post2: 1956 ± 1873dynes*s/cm2, p = 0.003), systolic pressure time index (Rest1: 1900 ± 290 mmHg*s; Rest2: 1937 ± 390 mmHg*s; Post1: 2769 ± 535 mmHg*s; Post2: 2652 ± 512 mmHg*s, p = 0.001), diastolic pressure time index (Rest1: 2827 ± 244 mmHg*s; Rest2: 2973 ± 294 mmHg*s; Post1: 2349 ± 319 mmHg*s; Post2: 2289 ± 402 mmHg*s, p = 0.001), and the subendocardial viability ratio (Rest1: 154 ± 34%; Rest2: 163 ± 44%; Post1: 90 ± 31%; Post2: 92 ± 33%, p = 0.001). While there were no significant differences from Rest1 to Rest2, there were significant increases for each of these variables such that Post1 and Post2 were augmented above Rest1 and Rest2. CONCLUSION: These data suggest that resistance exercise in conjunction with 4 mg/kg of caffeine does not mediate additional left ventricular workload compared to a placebo in resistance-trained women.

Acute caffeine supplementation enhances several aspects of shot put performance in trained athletes.

ABSTRACTThe aim of this investigation was to determine the effect of a moderate dose of caffeine (3 mg/kg/b.m.) on muscular power and strength and shot put performance in trained athletes. Methods. Thirteen shot putters (eight men and five women) participated in a double-blind, placebo-controlled, randomized experiment. In two different trials, participants ingested either 3 mg/kg/b.m. of caffeine or a placebo. Forty-five min after substance ingestion, athletes performed a handgrip dynamometry test, a countermovement jump (CMJ), a squat jump (SJ), and a maximum-velocity push-up. The athletes also performed three types of throws: a backwards throw, a standing shot put and a complete shot put. Results. In comparison with the placebo, caffeine ingestion increased CMJ height (32.25 ± 7.26 vs. 33.83 ± 7.72 cm, respectively; effect size (ES) = 0.82, p = 0.012; +5.0%;) and SJ height (29.93 ± 7.88 vs. 31.40 ± 7.16 cm; ES = 0.63, p = 0.042; +6.4%) and distance in the standing shot put (10.27 ± 1.77 m vs. 10.55 ± 1.94 m; ES = 0.87, p = 0.009; +2.6%). However, caffeine ingestion did not increase strength in the handgrip test, power in the ballistic push-up, or distance in the backwards throw (all p > 0.05). Shot put performance changed from 11.24 ± 2.54 to 11.35 ± . 2.57 m (ES = 0.33, p = 0.26; +1.0%), although the difference did not reach statistically significant differences. Caffeine ingestion did not increase the prevalence of side effects (nervousness, gastrointestinal problems, activeness, irritability, muscular pain, headache, and diuresis) in comparison with the placebo (p > 0.05). Conclusion. In summary, caffeine ingestion with a dose equivalent to 3 mg/kg/b.m. elicited moderate improvements in several aspects of physical performance in trained shot putters but with a small effect on distance in a complete shot put.

Acute caffeine supplementation and live match-play performance in team-sports: A systematic review (2000–2021)

ABSTRACT Caffeine is a psycho-active stimulant that can improve physical and cognitive performance. We systematically reviewed the evidence on the effects of acute caffeine ingestion on physiological parameters, physical and technical-skill performance during high-performance team-sport match-play. Following PRISMA guidelines, studies were identified using scientific databases (PubMed, Web-of-Science, Scopus, and SPORTDiscus) in February 2021. Of 281 results, 13 studies met inclusion, totalling 213 participants. Included studies adopted the randomised double-blinded cross-over design, involving caffeine and control conditions. In studies reporting physiological variables, responses to caffeine included higher peak (n=6/ 8 [n/ total studies measuring the variable]) and mean (n=7/ 9) heart rates, increased blood glucose (n=2/ 2) and lactate (n=2/ 2) concentrations. Improvements in physical performance were widely documented with caffeine, including greater distance coverage (n=7/ 7), high-speed distance coverage (n=5/ 7) and impact frequencies (n=6/ 8). From three studies that assessed technical-skills, it appears caffeine may benefit gross-skill performance, but have no effect, or negatively confound finer technical-skill outcomes. There is compelling evidence that ingesting moderate caffeine doses (~3 to 6 mg·kg−1) ~60 minutes before exercise may improve physical performance in team-sports, whereas evidence is presently too scarce to draw confident conclusions regarding sport-specific skill performance.

Acute caffeine and capsaicin supplementation and performance in resistance training

Aim: This study aimed to evaluate the acute supplementation effects of capsaicin, caffeine, and the combined capsaicin plus caffeine on total volume (total repetitions x weight lifted), rate of perceived exertion (RPE), and side-effects on resistance training. Methods: Eleven men (21.5 ± 2.1 years, 1.75 ± 0.08 m, 79.64 ± 10.1 kg), trained in resistance training (experience of 4.5 ± 2.6 years, weekly frequency 5 ± 0.8 days) were recruited. This was a crossover, randomized, double-blind study. Each volunteer went through four experimental conditions: supplemented with capsaicin (12 mg), caffeine (400 mg), capsaicin plus caffeine (12 mg and 400 mg, respectively), or placebo. After supplementation, the volunteers completed four sets of back squats until failure, at 70% of one-repetition maximum, with 90 s of rest interval between sets. RPE was registered at the end of each set. Volunteers were asked about the occurrence of side effects, right after exercise and 24 h after supplementation. Results: No significant differences were found (p > 0.05) in total volume between placebo (5505.2 ± 810.7 kg), capsaicin (6010.0 ± 1067.0 kg), capsaicin plus caffeine (5885.1 ± 1219.3 kg), and Caffeine (5628.6 ± 894.4 kg). No significant differences were found in RPE (p > 0.05) between the experimental conditions. The effect size of the total volume was small in capsaicin and capsaicin plus caffeine (d = 0.62 e d = 0.47, respectively), and trivial in the caffeine condition (d = 0.15). Conclusion: The supplementation failed to influence resistance training performance as well as had no effects on increasing the total volume or reducing RPE.

CYP1A2 Genotype Polymorphism Influences the Effect of Caffeine on Anaerobic Performance in Trained Males.

The purpose was to investigate the effects of CYP1A2 -163C > A polymorphism on the effects of acute caffeine (CAF) supplementation on anaerobic power in trained males. Sixteen trained males (age: 21.6 ± 7.1years; height: 179.7 ± 5.6cm; body mass: 72.15 ± 6.8kg) participated in a randomized, double-blind, placebo (PLA) controlled crossover design. Participants supplemented with CAF (6mg/kg of body mass) and an isovolumetric PLA (maltodextrin) in random order and separated by 7 days, before an all-out 30-s anaerobic cycling test to determine peak, average, and minimum power output, and fatigue index. Genomic deoxyribonucleic acid was extracted to identify each participants CYP1A2 genotype. Six participants expressed AA homozygote and 10 expressed C alleles. There was a treatment by genotype interaction for peak power output (p = .041, η2 = .265, observed power = 0.552) with only those expressing AA genotype showing improvement following CAF supplementation compared with PLA (CAF: 693 ± 108 watts vs. PLA: 655 ± 97 watts; p = .039), while no difference between treatments was noted in those expressing C alleles (CAF: 614 ± 92watts vs. PLA: 659 ± 144watts; p = .135). There were no other interaction or main effects for average or minimum power output, or fatigue index (p > .05). In conclusion, the ingestion of 6mg/kg of CAF improved peak power output only in participants with the AA genotype compared with PLA; however, expression of the CYP1A2 did not influence average or minimum power output or fatigue index.

The Effects of Acute Caffeine Supplementation on Repeated-Sprint Ability in Healthy Young Non-Athletes

The Effects of Acute Caffeine Supplementation on Repeated-Sprint Ability in Healthy Young Non-Athletes

Does Acute Caffeine Supplementation Improve Physical Performance in Female Team-Sport Athletes? Evidence from a Systematic Review and Meta-Analysis.

Introduction: Recent original research and meta-analyses suggest that acute caffeine supplementation improves exercise performance in team-sport athletes (TSA). Nonetheless, most of the studies testing the effects of caffeine on TSA included samples of male athletes, and there is no meta-analysis of the performance-enhancing effects of caffeine on female TSA. The aim of the present study was to synthesize the existing literature regarding the effect of caffeine supplementation on physical performance in adult female TSA. Methods: A search was performed in Pubmed/Medline, SPORTDiscus and Scopus. The search was performed from the inception of indexing until 1 September 2021. Crossover randomized controlled trials (RCT) assessing the effects of oral caffeine intake on several aspects of performance in female TSA were selected. The methodological quality and risk of bias were assessed for individual studies using the Physiotherapy Evidence Database scale (PEDro) and the RoB 2 tool. A random-effects meta-analysis of standardized mean differences (SMD) was performed for several performance variables. Results: The search retrieved 18 articles that fulfilled the inclusion/exclusion criteria. Overall, most of the studies were of excellent quality with a low risk of bias. The meta-analysis results showed that caffeine increased performance in specific team-sport skills (SMD: 0.384, 95% confidence interval (CI): 0.077–0.691), countermovement jump (SMD: 0.208, CI: 0.079–0.337), total body impacts (SMD: 0.488; 95% CI: 0.050, 0.927) and handgrip strength (SMD: 0.395, CI: 0.126–0.665). No effects were found on the ratings of perceived exertion, squat jumps, agility, repeated sprint ability or agility tests performed after fatigue. Conclusions: The results of the meta-analysis revealed that acute caffeine intake was effective in increasing some aspects of team-sports performance in women athletes. Hence, caffeine could be considered as a supplementation strategy for female athletes competing in team sports.

Effect of acute caffeine supplementation before intermittent high-intensity exercise on cytokine levels and psychobiological parameters: A randomized, cross-over, placebo-controlled trial

The present study aimed to verify the effects of caffeine supplementation on psychobiological parameters and its relationship with inflammatory cytokines in non-athlete subjects. We hypothesized that IL-10 may be responsible for the reduction in fatigue perception in response to caffeine supplementation. It was a randomized, double-blinded, cross-over, placebo-controlled study. Ten non-athlete subjects (26.9 ± 4.01 years old; 73.44 ± 9.57 kg; 15.94 ± 4.32 body fat kg) were evaluated. Sixty-min after caffeine (6 mg−1.kg−1 body mass) or placebo supplementation, high-intensity interval exercise test (1 min at 90% of Wmax and 2 min at 50% of Wmax) was performed to maximum voluntary exhaustion. Cytokine concentrations and psychobiological parameters were evaluated before (BE), immediately after (post-PE) and 1 h after exercise (1 h post-PE). We verify that IL-6 (0.35; 95% CI: 0.13 to 0.56; z = 3.24; p = 0.001; d = 1.14) and IL-10 (9.06; 95% CI 0.41 to 17.70; z = 2.05; p = 0.04; d = 1.12) increases post-PE in CAF group versus PLA group. Still, IL-10 levels were higher in CAF group 1 h post-PE (25.04; 95% CI: 8.95 to 41.31; z = 3.05; p = 0.002; d = 1.9) than PLA group. Moreover, 1 h post-PE vigor level was higher in the CAF group versus PLA group (4.53; 95% CI: 1.27 to 7.80; z = 2.72; p = 0.006; d = 0.46), and fatigue was lower in CAF group than PLA group (-5.08; 95% CI: −9.93 to −0.227; z = -2.05; p = 0.040; d = 0.67). We conclude that 1 h post-PE caffeine was able to decrease fatigue and increase vigor perception. IL-10 levels were higher 1 h post-PE in CAF group, suggesting, according to our hypothesis, that IL-10 may be associated with decrease fatigue perceptions after exercise.

Habitual Caffeine Consumption Does Not Interfere With the Acute Caffeine Supplementation Effects on Strength Endurance and Jumping Performance in Trained Individuals.

The long-standing caffeine habituation paradigm was never investigated in strength endurance and jumping exercise performance through a straightforward methodology. The authors examined if habitual caffeine consumption would influence the caffeine ergogenic effects on strength endurance and jumping performance as well as perceptual responses. Thirty-six strength-trained individuals were mathematically allocated into tertiles according to their habitual caffeine consumption: low (20 ± 11mg/day), moderate (88 ± 33mg/day), and high consumers (281 ± 167mg/day). Then, in a double-blind, crossover, counterbalanced fashion, they performed a countermovement vertical jump test and a strength endurance test either after caffeine (6mg/kg) and placebo supplementation or after no supplementation (control). Perceptual responses such as ratings of perceived exertion and pain were measured at the termination of the exercises. Acute caffeine supplementation improved countermovement vertical jump performance (p = .001) and total repetitions (p = .004), regardless of caffeine habituation. Accordingly, analysis of absolute change from the control session showed that caffeine promoted a significantly greater improvement in both countermovement vertical jump performance (p = .004) and total repetitions (p = .0001) compared with placebo. Caffeine did not affect the rating of perceived exertion and pain in any exercise tests, irrespective of tertiles (for all comparisons, p > .05 for both measures). Caffeine side effects were similar in low, moderate, and high caffeine consumers. These results show that habitual caffeine consumption does not influence the potential of caffeine as an ergogenic aid in strength endurance and jumping exercise performance, thus challenging recommendations to withdraw from the habitual caffeine consumption before supplementing with caffeine.

Acute caffeine supplementation improves jumping, sprinting, and change-of-direction performance in basketball players when ingested in the morning but not evening

ABSTRACT This study compared the effects of acute caffeine supplementation (3 mg/kg) administered in the morning and evening on performance-related variables in basketball players. Eleven, national-level, adolescent male basketball players underwent field-based fitness testing on four occasions: morning (10:00) with caffeine ingestion (AMCAFF), morning (10:00) with placebo ingestion (AMPLAC), evening (21:00) with caffeine ingestion (PMCAFF), and evening (21:00) with placebo ingestion (PMPLAC). Fitness testing included of a countermovement jump without arm swing (CMJ), CMJ with arm swing (CMJAS), squat jump (SJ), Lane Agility Drill (LAD), 20-m linear sprint, and Suicide Run with (SRD) and without dribbling (SR). Data were analysed using two-way repeated measures analyses of variance and paired t-tests, with effect sizes (ES) also determined for all pairwise comparisons. Follow-up t-test comparisons revealed that AMCAFF produced small-moderate, significant (p<0.001), improvements in CMJ (ES = 0.51), CMJAS (ES = 0.40), SJ (ES = 0.51), and SR (ES = −0.45) compared to AMPLAC. AMCAFF also produced a moderate, significantly (p<0.001) faster LAD (ES = −0.61) compared to PMCAFF. PMPLAC demonstrated small-moderate, significant (p<0.05) improvements in CMJ (ES = 0.43), CMJAS (ES = 0.48), and 20-m sprint (ES = −0.63) compared to AMPLAC. In contrast, AMPLAC resulted in large, significantly (p<0.001), faster SRD (ES = −1.46) and SR (ES = −1.59) compared to PMPLAC. Given the ergogenic effects of caffeine during basketball-specific fitness tests appear to be influenced by time of ingestion, basketball practitioners should consider administering caffeine only to players in the morning to improve vertical jump, sprinting, and change-of-direction performance, with no beneficial effects observed with caffeine ingestion in the evening. Highlights The effect of caffeine supplementation on basketball-specific performance related variables were mediated by ingestion time in elite, adolescent basketball players. AMCAFF produced small-moderate improvements in vertical jump, change-of-direction, 20-m linear sprint, and repeated-sprint performance compared to AMPLAC while PMCAFF produced trivial differences in each performance-related variable compared to PMPLAC. Comparisons between ingestion times in the placebo condition revealed vertical jump height and 20-m sprint speed were impaired in the morning compared to the evening, but these time-dependent differences were eliminated when caffeine was consumed in the morning. Basketball practitioners should consider administering caffeine only to players in the morning to improve vertical jump, sprinting, and change-of-direction performance, with no beneficial effects observed with caffeine ingestion in the evening.

Caffeine Ingestion Improves Performance During Fitness Tests but Does Not Alter Activity During Simulated Games in Professional Basketball Players.

To examine the effects of acute caffeine supplementation on physical performance during fitness testing and activity during simulated games in basketball players. A double-blind, counterbalanced, randomized, crossover study design was followed. A total of 14 professional male basketball players ingested a placebo (sucrose) and caffeine (6mg·kg-1 of body mass) in liquid form prior to completing 2 separate testing sessions. Each testing session involved completion of a standardized 15-minute warm-up followed by various fitness tests including 20-m sprints, countermovement jumps, Lane Agility Drill trials, and a repeated-sprint-ability test. Following a 20-minute recovery, players completed 3 × 7-minute 5-vs-5 simulated periods of full-court basketball games, each separated by 2minutes of recovery. Local positioning system technology was used to measure player activity during games. Players completed a side-effects questionnaire 12 to 14hours after testing. Players experienced significant (P < .05), moderate-very large (effect size = -2.19 to 0.89) improvements in 20-m sprint, countermovement jump, Lane Agility Drill, and repeated-sprint-ability performance with caffeine supplementation. However, external workloads completed during simulated games demonstrated nonsignificant, trivial-small (effect size = -0.23 to 0.12) changes between conditions. In addition, players reported greater (P < .05) insomnia and urine output after caffeine ingestion. Acute caffeine supplementation could be effective to improve physical performance during tests stressing fitness elements important in basketball. However, acute caffeine supplementation appears to exert no meaningful effects on the activity completed during simulated basketball games and may promote sleep disturbances and exert a diuretic effect when taken at 6mg·kg-1 of body mass in professional players.

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

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. This review was performed in accordance with the PRISMA guidelines. The search for studies was performed through nine databases. 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 ≥ 10km) and ingesting caffeine 60min 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). 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.