Article

Effect Of Coffee And Caffeine Ingestion On Resistance Exercise Performance

February 2016
The Journal of Strength and Conditioning Research 30(10)

DOI:10.1519/JSC.0000000000001382

Authors:

Darren Richardson

Coventry University

Neil David Clarke

Coventry University

The aim of the present study was to determine the effect on performance of ingesting caffeine-dose matched anhydrous caffeine, coffee or decaffeinated coffee plus anhydrous caffeine during resistance exercise. Nine resistance trained males (Mean±SD age: 24±2 years, weight: 84±8kg, height: 180±8cm) completed a squat and bench press exercise protocol at 60% 1-RM until failure on five occasions consuming either, 0.15 g·kg caffeinated coffee (COF), 0.15 g·kg decaffeinated coffee (DEC), 0.15 g·kg decaffeinated coffee plus 5 mg·kg anhydrous caffeine (D+C), 5 mg·kg anhydrous caffeine (CAF) or a placebo (PLA). Felt arousal and rating of perceived exertion (RPE) were used to assess perceptual variables and heart rate (HR) to assess physiological responses between trials. There were significant differences in total weight lifted for the squat between conditions (P<0.01; ηP =0.54) with a greater amount lifted during D+C compared with DEC (P<0.01), CAF (P<0.05) and PLA (P<0.05) conditions. Total weight lifted during the COF condition was significantly greater than PLA (P<0.01), although not significantly greater than the amount of weight lifted during the DEC condition (P=0.082). No significant differences were observed in total weight lifted in the bench press protocol between conditions (P=0.186; ηP =0.17). Significant differences in HR (P<0.01; ηP =0.39), but not RPE (squat: P=0.690; ηP =0.07; bench press: P=0.165; ηP =0.18) and felt arousal (P=0.056; ηP =0.24) were observed between conditions. Coffee and decaffeinated coffee plus caffeine have the ability to improve performance during a resistance exercise protocol, although possibly not over multiple bouts.

Effects of carbohydrate and caffeine mouth rinsing on strength, muscular endurance and cognitive performance

Article

Full-text available

Sep 2021
Sports Nutr Rev J

Background Carbohydrate (CHO) and caffeine (CAF) mouth rinsing have been shown to enhance endurance and sprint performance. However, the effects of CHO and CAF mouth rinsing on muscular and cognitive performance in comparison between male and female athletes are less well-established. The aim of this study was to examine the effect of CHO and CAF rinsing on squat and bench press 1 repetition maximum (1-RM) strength, 3 sets of 40% of 1-RM muscular endurance and cognitive performance in both male and female athletes. Methods Thirteen male and fourteen female resistance-trained participants completed four testing sessions following the rinsing of 25 ml of i) 6% of CHO (1.5 g); ii) 2% CAF (500 mg), iii) combined CHO and CAF (CHOCAF) solutions or iv) water (PLA) for 10 s. Heart rate (HR), felt arousal (FA), ratings of perceived exertion (RPE) and glucose (GLU) were recorded throughout the test protocol. Results There were no significant differences in squat and bench press 1-RM, HR, RPE and GLU ( p > 0.05) for males and females, respectively. FA was significantly increased with CAF ( p = 0.04, p = 0.01) and CHOCAF ( p = 0.03, p = 0.01) condition in both males and females, respectively. Squat endurance performance in the first set was significantly increased with CHOCAF condition compared to PLA in both males ( p = 0.01) and females ( p = 0.02). Bench press endurance was similar for all conditions in both genders ( p > 0.05). Cognitive performance was significantly increased with CHOCAF compared to PLA in males ( p = 0.03) and females ( p = 0.02). Conclusion Combined CHO and CAF mouth rinsing significantly improved lower body muscular endurance and cognitive performance in both males and females.

International society of sports nutrition position stand: caffeine and exercise performance

Article

Full-text available

Jan 2021
Sports Nutr Rev J

Following critical evaluation of the available literature to date, The International Society of Sports Nutrition (ISSN) position regarding caffeine intake is as follows: 1. Supplementation with caffeine has been shown to acutely enhance various aspects of exercise performance in many but not all studies. Small to moderate benefits of caffeine use include, but are not limited to: muscular endurance, movement velocity and muscular strength, sprinting, jumping, and throwing performance, as well as a wide range of aerobic and anaerobic sport-specific actions. 2. Aerobic endurance appears to be the form of exercise with the most consistent moderate-to-large benefits from caffeine use, although the magnitude of its effects differs between individuals. 3. Caffeine has consistently been shown to improve exercise performance when consumed in doses of 3–6 mg/kg body mass. Minimal effective doses of caffeine currently remain unclear but they may be as low as 2 mg/kg body mass. Very high doses of caffeine (e.g. 9 mg/kg) are associated with a high incidence of side-effects and do not seem to be required to elicit an ergogenic effect. 4. The most commonly used timing of caffeine supplementation is 60 min pre-exercise. Optimal timing of caffeine ingestion likely depends on the source of caffeine. For example, as compared to caffeine capsules, caffeine chewing gums may require a shorter waiting time from consumption to the start of the exercise session. 5. Caffeine appears to improve physical performance in both trained and untrained individuals. 6. Inter-individual differences in sport and exercise performance as well as adverse effects on sleep or feelings of anxiety following caffeine ingestion may be attributed to genetic variation associated with caffeine metabolism, and physical and psychological response. Other factors such as habitual caffeine intake also may play a role in between-individual response variation. 7. Caffeine has been shown to be ergogenic for cognitive function, including attention and vigilance, in most individuals. 8. Caffeine may improve cognitive and physical performance in some individuals under conditions of sleep deprivation. 9. The use of caffeine in conjunction with endurance exercise in the heat and at altitude is well supported when dosages range from 3 to 6 mg/kg and 4–6 mg/kg, respectively. 10. Alternative sources of caffeine such as caffeinated chewing gum, mouth rinses, energy gels and chews have been shown to improve performance, primarily in aerobic exercise. 11. Energy drinks and pre-workout supplements containing caffeine have been demonstrated to enhance both anaerobic and aerobic performance.

Effects of Different Doses of Caffeinated Coffee on Muscular Endurance, Cognitive Performance, and Cardiac Autonomic Modulation in Caffeine Naive Female Athletes

Article

Full-text available

Dec 2020

Caffeine is widely consumed among elite athletes for its well-known ergogenic properties, and its ability to increase exercise performance. However, studies to date have predominantly fo-cused on the anhydrous form of caffeine in male participants. The aim of the study was to investigate the effect of caffeinated coffee ingestion on lower-upper body muscular endurance, cognitive performance, and heart rate variability (HRV) in female athletes. A total of 17 participants (mean ± standard deviation (SD): age = 23 ± 2 years, body mass = 64 ± 4 kg, height = 168 ± 3 cm) in a random-ized cross-over design completed three testing sessions, following the ingestion of 3 mg/kg/bm of caffeine (3COF), 6 mg/kg/bm of caffeine (6COF) provided from coffee or decaffeinated coffee (PLA) in 600 mL of hot water. The testing results included: (1) repetition number for muscular endurance performance; (2): reaction time and response accuracy for cognitive performance; (3): HRV parameters , such as standard deviation of normal-to-normal (NN) intervals (SDNN), standard deviation of successive differences (SDSD), root mean square of successive differences (RMSSD), total power (TP), the ratio of low-and high-frequency powers (LF/HF), high-frequency power (HF), normalized HF (HFnu), low-frequency power (LF), and normalized LF (LFnu). A one-way repeated measures ANOVA revealed that 3COF (p = 0.024) and 6COF (p = 0.036) improved lower body muscular endurance in the first set as well as cognitive performance (p = 0.025, p = 0.035 in the post-test, respectively) compared to PLA. However, no differences were detected between trials for upper body muscular endurance (p = 0.07). Lastly, all HRV parameters did not change between trials (p > 0.05). In conclusion, ingesting caffeinated coffee improved lower body muscular endurance and cognitive performance, while not adversely affecting cardiac autonomic function.

The Effects of Low-Dose Caffeinated Coffee Ingestion on Strength and Muscular Endurance Performance in Male Athletes

Article

Full-text available

Mar 2021
PROG NUTR

Aim: Caffeine, especially in the form of coffee, are widely consumed among athletes to increase performance. Its effects on aerobic exercise is well-established, yet reports in strength and muscular endurance performance is equivocal. The aim of this study is to investigate the effects of acute low dose (3 mg/kg) of caf-feinated coffee ingestion on upper-lower body strength and muscular endurance performance in moderately strength trained men aged between 18-26 years. Methods: 14 moderately resistance-trained men (mean ± SD: weight-82.64 ± 9.92, height-181.00 ± 7.68, body fat percentage-15.25 ± 5.43) performed lower-upper body 1RM and %60 1RM to failure test protocol on 2 occasions ingesting 0.09 gr/kg caffeinated coffee (COF) or 0.09 gr/kg decaffeinated coffee (PLA). Heart rate (HR), blood pressure (BP) and rating of perceived exertion (RPE) were measured at different time points during test protocol. Results: There were no statistical differences in upper body strength (p=0.281), muscular endurance (p=0.727) and lower body strength (p=0.414) performance between COF and PLA trials. COF trial showed a trend for increased lower body muscular endurance performance by 8.8% compared to the PLA (p = 0.057). No significant differences were observed in HR, BP and RPE between trials (p>0.05). Conclusion: Ingestion of acute low dose of caffeinated coffee may increase lower body muscular endurance performance on moderately strength trained athletes. The lack of statistical significance in lower body muscular endurance performance may be related to the ingesting low dose of caffeine, training status and high level of habitual caffeine consumption of the participants'

Effects of caffeine supplementation on muscle endurance, maximum strength, and perceived exertion in adults submitted to strength training: a systematic review and meta-analyses

Article

Jun 2020

This study aimed to determine the effects of caffeine supplementation on muscle endurance, maximum strength, and ratings of perceived exertion (RPE) in individuals undergoing strength training with external resistance exercises. A search of three databases (PubMed, LiLACS, and CENTRAL) and gray literature was carried out to find randomized controlled trials, with a double-blind design, which investigated the effects of caffeine supplementation in healthy adults. Meta-analyses of weighted mean differences (WMD) and standardized mean differences (SMD) between caffeine and placebo groups from individual studies were performed using a random-effects model. Nineteen studies were included in the quantitative synthesis. Only the bench press and the leg press exercises were assessed in a sufficient number of studies to be included in meta-analyses. In the bench press exercise, caffeine supplementation improved strength resistance (WMD 0.87 (95% confidence interval (CI): 0.33, 1.41) repetitions, P = 0.001; 15 studies), and maximum strength (WMD 2.01 (95% CI: 0.20, 3.80) kg, P = 0.02; 7 studies), but showed no effect in RPE (SMD -0.45 (95% CI: −1.40, 0.48), P = 0.34, 7 studies) In the leg press exercise, no significant improvement were observed in muscle endurance (WMD: 1.24 (95% CI: −0.21, 2.70) repetitions, P = 0.09, 8 studies), maximum strength (WMD 8.49 (95% CI: −11.91, 28.90) kg, P = 0.415, 3 studies), and in RPE (SMD -0.17 (95% CI: −1.62, 1.27), P = 0.812, 3 studies). Caffeine supplementation showed a significant ergogenic effect on muscle endurance and maximum strength in the bench press exercise. More investigations are needed to clarify the contradictions in its effects regarding lower-body exercises.

Is Coffee a Useful Source of Caffeine Preexercise?

Article

Jan 2020

Caffeine is a well-established ergogenic aid, with its performance-enhancing effects demonstrated across a wide variety of exercise modalities. Athletes tend to frequently consume caffeine as a performance enhancement method in training and competition. There are a number of methods available as a means of consuming caffeine around exercise, including caffeine anhydrous, sports drinks, caffeine carbohydrate gels, and gum. One popular method of caffeine ingestion in nonathletes is coffee, with some evidence suggesting it is also utilized by athletes. In this article, we discuss the research pertaining to the use of coffee as an ergogenic aid, exploring (a) whether caffeinated coffee is ergogenic, (b) whether dose-matched caffeinated coffee provides a performance benefit similar in magnitude to caffeine anhydrous, and (c) whether decaffeinated coffee consumption affects the ergogenic effects of a subsequent isolated caffeine dose. There is limited evidence that caffeinated coffee has the potential to offer ergogenic effects similar in magnitude to caffeine anhydrous; however, this requires further investigation. Coingestion of caffeine with decaffeinated coffee does not seem to limit the ergogenic effects of caffeine. Although caffeinated coffee is potentially ergogenic, its use as a preexercise caffeine ingestion method represents some practical hurdles to athletes, including the consumption of large volumes of liquid and difficulties in quantifying the exact caffeine dose, as differences in coffee type and brewing method may alter caffeine content. The use of caffeinated coffee around exercise has the potential to enhance performance, but athletes and coaches should be mindful of the practical limitations.

Effects of caffeine, methylliberine, and theacrine on vigilance, marksmanship, and hemodynamic responses in tactical personnel: a double-blind, randomized, placebo-controlled trial

Article

Full-text available

Dec 2022
Sports Nutr Rev J

Background Tactical athletes require fast reaction times (RT) along with high levels of vigilance and marksmanship performance. Caffeine has been shown to improve these measures but also results in increased blood pressure and jitteriness. Research on other purine alkaloids, such as methylliberine and theacrine, has suggested they do not increase blood pressure or jitteriness to the same extent, but their impact on tactical performance is unknown. Methods A between-subjects, randomized, placebo-controlled design was used to test the effects of placebo (PLA), 300 mg caffeine (CAF), and a combination of 150 mg caffeine, 100 mg methylliberine, and 50 mg theacrine (CMT) on RT and marksmanship along with hemodynamic and arousal measures following a sustained vigilance task in tactical personnel (n = 48). Following consumption of the supplement, participants underwent a 150-min protocol consisting of two rounds. Each round began with leisurely reading followed by a 30-min vigilance task before beginning two trials of movement and marksmanship tasks. Hemodynamics and felt arousal were assessed throughout the protocol. Composite Z-scores were calculated for overall performance measures at each timepoint, and mixed-effects models were used to assess differences in RT, accuracy, and composite Z-scores along with hemodynamics and felt arousal. An α-level of 0.05 was used to determine statistical significance, and Cohen’s d was used to quantify effect sizes. Results A Group-by-Time interaction for vigilance RT (P = 0.038) indicated improvements for both CAF and CMT from round 1 to round 2 (P < 0.01) while PLA did not change (P = 0.27). No Group main effects or Group-by-Time interactions were found for movement or marksmanship performance (P > 0.20). Group main effects for systolic (SBP; P = 0.001) and diastolic blood pressure (DBP; P = 0.028) indicated higher SBP in CAF (P = 0.003, d= 0.84) and CMT (P = 0.007, d= 0.79) compared to PLA but only higher DBP in CAF (P = 0.025, d= 0.74). No Group-by-Time interaction or Group main effect was found for felt arousal (P > 0.16). Conclusions These findings suggest similar benefits on RT during a vigilance task between CAF, containing 300 mg caffeine, and CMT above PLA, though CAF resulted in slightly less favorable hemodynamic changes. This study is the first to provide data showing similar efficacy of combined caffeine, methylliberine, and theacrine compared to double the caffeine dose consumed alone on vigilance RT but without a significant rise in DBP above PLA in tactical personnel.

Timing of ergogenic aids and micronutrients on muscle and exercise performance

Article

Full-text available

Sep 2019
Sports Nutr Rev J

The timing of macronutrient ingestion in relation to exercise is a purported strategy to augment muscle accretion, muscle and athletic performance, and recovery. To date, the majority of macronutrient nutrient timing research has focused on carbohydrate and protein intake. However, emerging research suggests that the strategic ingestion of various ergogenic aids and micronutrients may also have beneficial effects. Therefore, the purpose of this narrative review is to critically evaluate and summarize the available literature examining the timing of ergogenic aids (caffeine, creatine, nitrates, sodium bicarbonate, beta-alanine) and micronutrients (iron, calcium) on muscle adaptations and exercise performance. In summary, preliminary data is available to indicate the timing of caffeine, nitrates, and creatine monohydrate may impact outcomes such as exercise performance, strength gains and other exercise training adaptations. Furthermore, data is available to suggest that timing the administration of beta-alanine and sodium bicarbonate may help to minimize known untoward adverse events while maintaining potential ergogenic outcomes. Finally, limited data indicates that timed ingestion of calcium and iron may help with the uptake and metabolism of these nutrients. While encouraging, much more research is needed to better understand how timed administration of these nutrients and others may impact performance, health, or other exercise training outcomes.

Caffeinated Gel Ingestion Enhances Jump Performance, Muscle Strength, and Power in Trained Men

Article

Full-text available

Apr 2019

We aimed to explore the effects of caffeinated gel ingestion on neuromuscular performance in resistance-trained men. The participants (n = 17; mean ± standard deviation (SD): age 23 ± 2 years, height 183 ± 5 cm, body mass 83 ± 11 kg) completed two testing conditions that involved ingesting a caffeinated gel (300 mg of caffeine) or placebo. The testing outcomes included: (1) vertical jump height in the squat jump (SJ) and countermovement jump (CMJ); (2) knee extension and flexion peak torque and average power at angular velocities of 60 • ·s −1 and 180 • ·s −1 ; (3) barbell velocity in the bench press with loads corresponding to 50%, 75%, and 90% of one-repetition maximum (1RM); and (4) peak power output in a test on a rowing ergometer. Compared to the placebo, caffeine improved: (1) SJ (p = 0.039; Cohen's d effect size (d) = 0.18; +2.9%) and CMJ height (p = 0.011; d = 0.18; +3.3%); (2) peak torque and average power in the knee extensors at both angular velocities (d ranged from 0.21 to 0.37; percent change from +3.5% to +6.9%), peak torque (p = 0.034; d = 0.24; +4.6%), and average power (p = 0.015; d = 0.32; +6.7%) at 60 • ·s −1 in the knee flexors; (3) barbell velocity at 50% 1RM (p = 0.021; d = 0.33; +3.5%), 75% 1RM (p < 0.001; d = 0.42; +5.4%), and 90% 1RM (p < 0.001; d = 0.59, +12.0%). We conclude that the ingestion of caffeinated gels may acutely improve vertical jump performance, strength, and power in resistance-trained men.

Caffeine and resistance exercise: the effects of two caffeine doses and the influence of individual perception of caffeine

Article

Apr 2019
EUR J SPORT SCI

Although caffeine is a widely used ergogenic resource, some information regarding its effects on resistance exercises is still lacking. The objective of the present study was to verify the acute effect of the ingestion of two different doses of caffeine on performance during a session of resistance exercises and to analyze the perception of the subjects in relation to the intake of caffeine. Following a double-blind, randomised, cross-over, controlled, and non-placebo design, 14 trained and healthy men (24.7 ± 6.8 years; 79.8 ± 9.8 kg; 177.3 ± 8.5 cm) performed a training session in chest-press, shoulder-press, and biceps curl exercises (3 sets until exhaustion; 70% 1RM; 3 min rest interval; 2 s for each concentric and eccentric phase) on three non-consecutive days after ingestion of 3 mg.kg −1 caffeine (CAF3), 6 mg.kg −1 caffeine (CAF6), or no substance (CON). Subjects were informed that one of the caffeine doses would be placebo. The total number of repetitions performed in CON (93.6 ± 22.4) was significantly lower than in CAF3 (108.0 ± 19.9, P = 0.02) and in CAF6 (109.3 ± 19.8, P = 0.03) and there were no differences between caffeine doses. Eight subjects noticed that caffeine was in CAF3 and six in CAF6 and there were no differences in the number of repetitions between sessions in which the subjects perceived and did not perceive caffeine. In conclusion, caffeine doses of 3 or 6 mg.kg −1 similarly increased performance in resistance upper limb exercises, independent of the subject's perception of substance ingestion.

The acute effects of caffeine intake on time under tension and power generated during the bench press movement

Article

Full-text available

Feb 2019
Sports Nutr Rev J

Background The ability to generate high levels of power is one of the key factors determining success in many sport disciplines. Although there are studies confirming ergogenic effects of caffeine (CAF) on different physical and mental abilities, much controversy remains about its influence on power. The main goal of this study was to assess the effects of caffeine supplementation on time under tension (TUT) and the number of performed repetitions (REP). The second objective was to determine the effects of CAF supplementation on power (P) and movement velocity (V) during the bench press movement. Additionally the authors evaluated whether CAF has a significant effect on velocity of the bar in the eccentric (ECC) phase (VEMEAN) of the bench press movement. Methods The study included 20 men (20–31 yrs., 87.3 ± 7.7 kg) with at least 2 years of experience in resistance training. The study participants were divided randomly into two groups: the supplemented group ingested caffeine before exercise (GCAF), while the control group was given a placebo (GCON). The exercise protocol consisted of performing the bench press movement with a load equal to 70%1RM with maximal possible velocity (X/0/X/0). The experimental sets were performed to momentary muscular failure. Results The repeated measures ANOVA between the GCAF and GCON groups revealed statistically significant differences in 2 variables. Post-hoc tests demonstrated statistically significant differences in TUT when comparing the group supplemented with caffeine (13.689 s GCAF) to the one ingesting a placebo (15.332 s GCON) at p = 0.002. Significant differences were also observed in mean velocity during the eccentric phase of movement (0.690 m/s in the GCAF to 0.609 in GCON with p = 0.002). There were no significant differences in generated power and velocity in the CON phase of the movement between the GCAF and GCON. Conclusions The main finding of the study is that CAF ingestion increases movement velocity of the bar in the eccentric phase of the movement, what results in shortening of the time under tension (TUT) needed for performing a specific number of repetitions, without decreasing power and velocity in the CON phase of the movement.

The Influence of Caffeine Supplementation on Resistance Exercise: A Review

Article

Full-text available

Jan 2019
SPORTS MED

This paper aims to critically evaluate and thoroughly discuss the evidence on the topic of caffeine supplementation when performing resistance exercise, as well as provide practical guidelines for the ingestion of caffeine prior to resistance exercise. Based on the current evidence, it seems that caffeine increases both maximal strength and muscular endurance. Furthermore, power appears to be enhanced with caffeine supplementation, although this effect might, to a certain extent, be caffeine dose- and external load-dependent. A reduction in rating of perceived exertion (RPE) might contribute to the performance-enhancing effects of caffeine supplementation as some studies have observed decreases in RPE coupled with increases in performance following caffeine ingestion. However, the same does not seem to be the case for pain perception as there is evidence showing acute increases in resistance exercise performance without any significant effects of caffeine ingestion on pain perception. Some studies have reported that caffeine ingestion did not affect exercise-induced muscle damage, but that it might reduce perceived resistance exercise-induced delayed-onset muscle soreness; however, this needs to be explored further. There is some evidence that caffeine ingestion, compared with a placebo, may lead to greater increases in the production of testosterone and cortisol following resistance exercise. However, given that the acute changes in hormone levels seem to be weakly correlated with hallmark adaptations to resistance exercise, such as hypertrophy and increased muscular strength, these findings are likely of questionable practical significance. Although not without contrasting findings, the available evidence suggests that caffeine ingestion can lead to acute increases in blood pressure (primarily systolic), and thus caution is needed regarding caffeine supplementation among individuals with high blood pressure. In the vast majority of studies, caffeine was administered in capsule or powder forms, and therefore the effects of alternative forms of caffeine, such as chewing gums or mouth rinses, on resistance exercise performance remain unclear. The emerging evidence suggests that coffee might be at least equally ergogenic as caffeine alone when the caffeine dose is matched. Doses in the range of 3–9 mg·kg⁻¹ seem to be adequate for eliciting an ergogenic effect when administered 60 min pre-exercise. In general, caffeine seems to be safe when taken in the recommended doses. However, at doses as high as 9 mg·kg⁻¹ or higher, side effects such as insomnia might be more pronounced. It remains unclear whether habituation reduces the ergogenic benefits of caffeine on resistance exercise as no evidence exists for this type of exercise. Caution is needed when extrapolating these conclusions to females as the vast majority of studies involved only male participants.

Caffeine's Effects on an Upper-Body Resistance Exercise Workout

Article

Full-text available

Jun 2020

Salatto, RW, Arevalo, JA, Brown, LE, Wiersma, LD, and Coburn, JW. Caffeine's effects on an upper-body resistance exercise workout. J Strength Cond Res XX(X): 000-000, 2018-The purpose of this study was to examine the effects of caffeine on an upper-body resistance exercise workout. Fifteen men (mean ± SD: age, 23.1 ± 1.9 years; body mass, 89.1 ± 13.9 kg; height, 175 ± 6.1 cm) volunteered to come to the laboratory 3 times. During visit 1, 1-repetition maximum (RM) values were determined for the barbell bench press, incline barbell bench press, and dumbbell bench press exercises. For visit 2, subjects consumed either 800-mg caffeine or a placebo. Subjects then completed 3 sets to failure of each exercise using 80% of their 1RM. Visit 3 was the same as visit 2; however, participants consumed the opposite treatment as visit 2. Various perceptual measures were recorded before, during, and after the workouts. The results indicated that participants completed significantly more repetitions per set for the barbell bench press (4.80 ± 2.66) and incline barbell bench press (4.91 ± 2.29) in the caffeine condition compared with the placebo condition (4.42 ± 2.56 and 4.36 ± 2.11, respectively). Higher arousal scores were found in the caffeine condition. For vigor, participants reported higher scores with caffeine before warming up (caffeine = 10.20 ± 4.11, placebo = 6.20 ± 3.23) and mid workout (caffeine = 13.53 ± 2.29, placebo = 11.13 ± 2.79). These results suggest that caffeine has an ergogenic effect on strength workout performance due, at least in part, to positive effects on workout perception. Athletes and recreational lifters may want to consider the ingestion of caffeine before a resistance exercise workout.

Effects of Coffee Components on Muscle Glycogen Recovery: A Systematic Review

Article

Full-text available

Jan 2018

Coffee is one of the most consumed beverages in the world and it can improve insulin sensitivity, stimulating glucose uptake in skeletal muscle when adequate carbohydrate intake is observed. The aim of this review is to analyze the effects of coffee and coffee components on muscle glycogen metabolism. A literature search was conducted according to PRISMA and seven studies were included. They explored the effects of coffee components on various substances and signaling proteins. In one of the studies with humans, caffeine was shown to increase glucose levels, Ca2+/calmodulin-dependent protein kinase (CaMK) phosphorylation, glycogen resynthesis rates and glycogen accumulation after exercise. After intravenous injection of caffeine in rats, caffeine increased adenosine monophosphate-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) phosphorylation, and glucose transport. In in vitro studies caffeine raised AMPK and ACC phosphorylation, increasing glucose transport activity and reducing energy status in rat muscle cells. Cafestol and caffeic acid increased insulin secretion in rat beta-cells, and glucose uptake into human muscle cells. Caffeic acid also increased AMPK and ACC phosphorylation, reducing the energy status and increasing glucose uptake in rat muscle cells. Chlorogenic acid did not show any positive or negative effect. The findings from the current review must be taken with caution due to the limited number of studies on the subject. In conclusion, various coffee components had a neutral or positive role in the metabolism of glucose and muscle glycogen, whilst no detrimental effect was described. Coffee beverages should be tested as an option for athlete's glycogen recovery.

Performance of muscle strength and fatigue tolerance in young trained women supplemented with caffeine

Article

Full-text available

Apr 2017

Background: Verify the effect of caffeine supplementation on the muscular strength and fatigue tolerance of young trained women. Methods: Eight women of 25±5 years old, who had undergone a minimum of 12 months of continuous resisted training, body mass index 20-23 kg/m2 were submitted to four tests: one repetition maximum (1- RM, kg) to pull down (PD), hack squat (HS), bench press (BP), and; knee extension exhaustion (drop-set, 100/80/60 kg, repetitions) (DS). They perform the tests in four consecutive blocks one-week apart crossover system: basal without caffeine (B); first caffeine (C1); placebo with starch supplementation (P); second caffeine (C2). Caffeine supplementation 6 mg.kg-1 30 min before. The paired t test and repeated ANOVA with Tukey-Kramer were performed. Results: Respectively for B, C1, P and C2 to each test were PD (52, 54, 56, 55, p>0.05); HS (99, 109, 108, 121*; p<0.001); BP (22, 26*, 25*, 27*; p<0.05); DS (28, 35*,**, 30*, 37**; p<0.001). To comparison of B, P and mean caffeine (C1+C2/2) results respectively were: HS (99, 108*, 115***; p<0.05); BP (22, 25*, 26*; p<0.05); DS (28, 30#, 36**; p<0.01 and p<0.001). The delta ((C1+C2/2)- (B+P/2)) were PD=0 (p>0.05), HS=12 (p=0.04), BP = 3 (p=0.007), DS = 7 (p=00.1). Conclusions: Caffeine improved tolerance to exhaustion and has tendency to improve strength in this young women. Probably caffeine supplementation is useful to improve performance in women engaged in sports with these physical valences. An investigation with a major numbers of volunteers could elucidate some controversies observed here.

Synergistic Effect of Rhodiola rosea and Caffeine Supplementation on the Improvement of Muscle Strength and Muscular Endurance: A Pilot Study for Rats, Resistance Exercise-Untrained and -Trained Volunteers

Article

Full-text available

Jan 2023

Multi-level studies have shown that Rhodiola rosea (RHO) and Caffeine (CAF) have the potential to be nutritional supplements to enhance physical performance in resistance exercise-untrained and -trained subjects. This study examined the synergistic effects of RHO (262.7 mg/kg for rats and 2.4 g for volunteers) and CAF (19.7 mg/kg for rats and 3 mg/kg for volunteers) supplementation on improving physical performance in rats, resistance exercise-untrained volunteers and resistance exercise-trained volunteers. Rats and volunteers were randomly grouped into placebo, CAF, RHO and CAF+RHO and administered accordingly with the nutrients during the training procedure, and pre- and post-measures were collected. We found that RHO+CAF was effective in improving forelimb grip strength (13.75%), erythropoietin (23.85%), dopamine (12.65%) and oxygen consumption rate (9.29%) in the rat model. Furthermore, the current results also indicated that the combination of RHO+CAF significantly increased the bench press one-repetition maximum (1RM) (16.59%), deep squat 1RM (15.75%), maximum voluntary isometric contraction (MVIC) (14.72%) and maximum repetitions of 60% 1RM bench press (22.15%) in resistance exercise-untrained volunteers. Additionally, despite the excellent base level of the resistance exercise-trained volunteers, their deep squat 1RM and MVIC increased substantially through the synergistic effect of RHO and CAF. In conclusion, combined supplementation of RHO+CAF is more beneficial in improving the resistance exercise performance for both resistance exercise-untrained and -trained volunteers. The present results provide practical evidence that the synergies of RHO and CAF could serve as potential supplementary for individuals, especially resistance exercise-trained subjects, to ameliorate their physical performances effectively and safely.

Low and Moderate Doses of Caffeinated Coffee Improve Repeated Sprint Performance in Female Team Sport Athletes

Article

Full-text available

Oct 2022

The aim of this study was to determine the effect of low and moderate doses of caffeine ingestion via caffeinated coffee on repeated sprint test (RST) and plasma catecholamine concentration in trained female team-sport athletes. In a randomized, double-blind, crossover design, 13 female team-sport athletes (VO2max: 48.7 ± 4 mL·kg·min−1) completed three RST trials, separated by 4-day, 60 min post-ingestion of either 3 mg·kg−1 (LCOF) or 6 mg·kg−1 (MCOF) or placebo (PLA). The RST consisted of 12 × 4 s sprints on a cycle ergometer interspersed with 20 s of active recovery. Blood lactate (BLa) and glucose (GLU) and epinephrine and norepinephrine concentrations were collected before and 60 min after coffee ingestion, and after RST. Heart rate (HR) and ratings of perceived exertion (RPE) were measured at the beginning of RST, and after the 6th and 12th sprints. Average peak power score during RST was significantly improved after LCOF (p = 0.016) and MCOF (p = 0.041) compared to PLA, but peak and mean power output of the individual sprints, and fatigue index were not different between trials (all p > 0.05). Epinephrine and norepinephrine concentrations were significantly higher before and after RST in LCOF and MCOF compared to PLA (all p < 0.05). BLa was also higher after RST in both LCOF and MCOF compared to PLA (p = 0.005). HR, RPE, and GLU were not different between conditions (p > 0.05). In conclusion, low and moderate dose of caffeine ingestion can enhance the average peak power score during repeated sprints. These findings partly support low and moderate doses of caffeine supplementation via coffee as a nutritional ergogenic aid for trained female team-sport players during repeated sprint exercise.

One Week of Low or Moderate Doses of Caffeinated Coffee Consumption Does Not Induce Tolerance to The Acute Effects of Caffeine on Sprint Performance

Article

Full-text available

Dec 2021

Habituation to acute performance responses of caffeine intake is still an ongoing debate. The aim of this study was to evaluate the effects of acute and 1 week consumption of caffeinated coffee on intermittent sprint cycling performance (12x4s with 90s active recovery) (ISP). Twenty four male team-sport players randomly divided into 3 groups (8 athletes for each): 0.16 gr/kg decaffeinated coffee ingestion in a day for 1 week (PLAGROUP), 0.08 caffeinated + 0.08 decaffeinated coffee (providing 3 mg/kg caffeine) (0.16 gr/kg in total) (LOWGROUP) and 0.16 gr/kg caffeinated coffee (providing 6 mg/kg caffeine) (MODGROUP). In a randomized and double-blind design, participants underwent three test session: At the first two test sessions, ISP test was performed with acute ingestion of decaffeinated coffee (PLA) or 6 mg/kg of caffeine provided by coffee (FIRSTCAF) to test acute effects of caffeine intake. At the third test session, following to 1 week of coffee consumption, to test if tolerance develops, ISP was performed with ingestion 6 mg/kg of caffeine provided by coffee (SECONDCAF). A 2-way repeated measures ANOVA showed that although average peak (p=0,39; η2 =0,13) and average mean (p=0,11; η2 =0,15) power of total 12 sprints during ISP test were not statistically different between 1 week consumption groups, FIRSTCAF and SECONDCAF significantly increased peak power (p=0,01; η2 =0,44) and mean power (p=0,01; η2 =0,46) in the first three sprints compared to PLA in all consumption groups. It appears that no tolerance was developed in 1 week consumption of 3 or 6 mg/kg/day of caffeine provided by coffee.

The Dose-Effects of Caffeine on Lower Body Maximal Strength, Muscular Endurance, and Rating of Perceived Exertion in Strength-Trained Females

Article

Full-text available

Sep 2021

Caffeine supplementation has shown to be an effective ergogenic aid enhancing athletic performance, although limited research within female populations exists. Therefore, the aim of the investigation was to assess the effect of pre-exercise caffeine supplementation on strength performance and muscular endurance in strength-trained females. In a double-blind, randomised, counterbalanced design, fourteen strength-trained females using hormonal contraception consumed either 3 or 6 mg·kg−1 BM of caffeine or placebo (PLA). Following supplementation, participants performed a one-repetition maximum (1RM) leg press and repetitions to failure (RF) at 60% of their 1RM. During the RF test, rating of perceived exertion (RPE) was recorded every five repetitions and total volume (TV) lifted was calculated. Repeated measures ANOVA revealed that RF (p = 0.010) and TV (p = 0.012) attained significance, with pairwise comparisons indicating a significant difference between 3 mg·kg−1 BM and placebo for RF (p = 0.014), with an effect size of 0.56, and for 6 mg·kg−1 BM (p = 0.036) compared to the placebo, with an effect size of 0.65. No further significance was observed for 1RM or for RPE, and no difference was observed between caffeine trials. Although no impact on lower body muscular strength was observed, doses of 3 and 6 mg·kg−1 BM of caffeine improved lower body muscular endurance in resistance-trained females, which may have a practical application for enhancing resistance training stimuli and improving competitive performance.

Bibliometric Analysis of Studies on Coffee/Caffeine and Sport

Article

Full-text available

Sep 2021

This article provides an empirical overview of coffee/caffeine studies in relation to sport worldwide, an incipient but growing relationship that has existed since 1938, although systematized over time since 1999. The extracted articles were examined using a bibliometric approach based on data from 160 records stored in the Web of Science (JCR) between 1938 and August 2021, applying traditional bibliometric laws and using VOSviewer for data and metadata processing. Among the results, these articles highlight an exponential increase in scientific production in the last two decades, with a concentration in only 12 specific journals, the hegemony of the USA among the co-authorship networks of worldwide relevance, and the thematic and temporal segregation of the concepts under study. This article concludes a high fragmentation of the authors with the highest level of scientific production and an evolution of almost 20 years in relevant thematic topics, and a concurrent concentration in three large blocks: (1) coffee consumption and risk factors, (2) health and coffee consumption, and (3) metabolism and sport correlated with the intake of coffee, which are distanced in time, providing evidence of an evolution that gives way to the irruption of alternative visions in the relationship of coffee and caffeine with sport.

Effects of Caffeine on Resistance Exercise: A Review of Recent Research

Article

Full-text available

Nov 2021
SPORTS MED

Jozo Grgic

In the last few years, a plethora of studies explored the effects of caffeine on resistance exercise, demonstrating that this field of research is growing fast. This review evaluated and summarized the most recent findings. Given that toxic doses of caffeine are needed to increase skeletal muscle contractility, the binding of caffeine to adenosine receptors is likely the primary mechanism for caffeine’s ergogenic effects on resistance exercise. There is convincing evidence that caffeine ingestion is ergogenic for: (i) one-repetition maximum, isometric, and isokinetic strength; and (ii) muscular endurance, velocity, and power in different resistance exercises, loads, and set protocols. Furthermore, there is some evidence that caffeine supplementation also may enhance adaptations to resistance training, such as gains in strength and power. Caffeine ingestion is ergogenic for resistance exercise performance in females, and the magnitude of these effects seems to be similar to those observed in men. Habitual caffeine intake and polymorphisms within CYP1A2 and ADORA2A do not seem to modulate caffeine’s ergogenic effects on resistance exercise. Consuming lower doses of caffeine (e.g., 2 to 3 mg/kg) appears to be comparably ergogenic as consuming high doses of caffeine (e.g., 6 mg/kg). Minimal effective doses of caffeine seem to be around 1.5 mg/kg. Alternate caffeine sources such as caffeinated chewing gum, gel, and coffee are also ergogenic for resistance exercise performance. With caffeine capsules, the optimal timing of ingestion seems to be 30 to 60 minutes pre-exercise. Caffeinated chewing gums and gels may enhance resistance exercise performance even when consumed 10 minutes before exercise. It appears that caffeine improves performance in resistance exercise primarily due to its physiological effects. Nevertheless, a small portion of the ergogenic effect of caffeine seems to be placebo-driven.

The effects of different doses of caffeine on maximal strength and strength-endurance in women habituated to caffeine

Article

Full-text available

Mar 2021
Sports Nutr Rev J

Purpose The main goal of this study was to assess the acute effects of 3 and 6 mg of caffeine intake per kg of body mass (b.m.) on maximal strength and strength-endurance in women habituated to caffeine. Methods Twenty-one healthy resistance-trained female students (23.0 ± 0.9 years, body mass: 59.0 ± 6.6 kg), with a daily caffeine intake of 5.8 ± 2.6 mg/kg/b.m. participated in a randomized, crossover, double-blind design. Each participant performed three experimental sessions after ingesting either a placebo (PLAC) or 3 mg/kg/b.m. (CAF-3) and 6 mg/kg/b.m. (CAF-6) of caffeine. In each experimental session, the participants underwent a 1RM test and a strength-endurance test at 50 %1RM in the bench press exercise. Maximal load was measured in the 1RM test and the time under tension, number of preformed repetitions, power output and bar velocity were registered in the strength-endurance test. Results The one-way ANOVA showed a main effect of caffeine on 1RM bench press performance (F = 14.74; p < 0.01). In comparison to the PLAC (40.48 ± 9.21 kg), CAF-3 (41.68 ± 8.98 kg; p = 0.01) and CAF-6 (42.98 ± 8.79 kg; p < 0.01) increased 1RM bench press test results. There was also a significant increase in 1RM for CAF-6 when compared to CAF-3 ( p < 0.01). There was a main effect of caffeine on time under tension during the strength-endurance test (F = 13.09; p < 0.01). In comparison to the PLAC (53.52 ± 11.44 s), CAF-6 (61.76 ± 15.39 s; p < 0.01) significantly increased the time under tension during the maximal strength-endurance test. Conclusion An acute dose of 3-to-6 mg/kg/b.m. of caffeine improves maximum strength. However, these doses of caffeine had minimal ergogenic effect on strength-endurance performance in women habituated to caffeine.

The effects of different doses of caffeine on maximal strength and strength-endurance in women habituated to caffeine

Preprint

Full-text available

Aug 2020

PurposeThe main goal of this study was to assess the acute effects of 3 and 6 mg of caffeine intake per kg of body mass (b.m.) on maximal strength and strength-endurance in women habituated to caffeine. Methods Twenty-one healthy resistance-trained female university students (23.0±0.9 years, body mass: 59.0±6.6 kg), with a daily caffeine intake of 5.8±2.6 mg/kg/b.m. participated in a randomized, crossover, double-blind design. Each participant performed three experimental sessions after ingesting either a placebo (PLAC) or 3 mg/kg/b.m. (CAF-3) and 6 mg/kg/b.m. (CAF-6) of caffeine. In each experimental session, the participants underwent a 1RM test and a strength-endurance test at 50%1RM in the bench press exercise. Maximal load was measured in the 1RM test and the time under tension, number of preformed repetitions, power output and bar velocity were registered in the strength-endurance test. ResultsThe one-way ANOVA showed a main effect of caffeine on 1RM bench press performance (F=14.74; p <0.01). In comparison to the PLAC (40.48±9.21 kg), CAF-3 (41.68±8.98 kg; p =0.01) and CAF-6 (42.98±8.79 kg; p <0.01) increased 1RM bench press test results. There was also a main effect of caffeine on time under tension during the strength-endurance test (F=13.09; p <0.01). In comparison to the PLAC (53.52±11.44 s), CAF-6 (61.76±15.39 s; p <0.01) significantly increased the time under tension during the maximal strength-endurance test. Conclusion An acute dose of 3-to-6 mg/kg/b.m. of caffeine improves maximum muscle strength. However, the effect of these doses had minimal ergogenic effect on strength-endurance performance.

Caffeine Increases Muscle Performance During a Bench Press Training Session

Article

Full-text available

Jul 2020

Previous investigations have established the ergogenic effect of caffeine on maximal muscle strength, power output and strength-endurance. However, these investigations used testing protocols that do not replicate the structure of a regular strength training session. Thus, the aim of this study was to investigate the effect of acute caffeine ingestion on muscle performance during a simulated velocity-based training workout. In a double-blind, randomized and counterbalanced experiment, 12 participants performed two experimental trials after ingesting 3 mg/kg/b.m. of caffeine or a placebo. The trials consisted of 4 sets of 8 repetitions of the bench press exercise at 70% of their one-repetition maximum performed at maximal velocity. Bar velocity was recorded with a rotatory encoder and force, power output and work were calculated. Regarding the whole workout, caffeine increased mean bar velocity (+7.8%; p=0.002), peak bar velocity (+8.7%; p=0.006), mean force (+1.5%; p=0.002), mean power output (+10.1%; p=0.003) and peak power output (+8.2%; p=0.004) when compared to the placebo. The total work performed in the caffeine trial was superior to the placebo trial (7.01±2.36 vs 6.55±2.20 kJ, p=0.001). These results suggest that the acute intake of 3 mg/kg/b.m. of caffeine before a velocity-based strength workout increased muscle performance and the total work performed across the whole training session. Thus, caffeine can be considered as an effective strategy to enhance muscle performance during the bench press training sessions.

Coffee Ingestion Improves 5 km Cycling Performance in Men and Women by a Similar Magnitude

Article

Full-text available

Oct 2019

Caffeine is a well-established ergogenic aid, although research to date has predominantly focused on anhydrous caffeine, and in men. The primary aim of the present study was to investigate the effect of coffee ingestion on 5 km cycling time trial performance, and to establish whether sex differences exist. A total of 38 participants (19 men and 19 women) completed a 5 km time trial following the ingestion of 0.09 g·kg-1 coffee providing 3 mg·kg-1 of caffeine (COF), a placebo (PLA), in 300 mL of water, or control (CON). Coffee ingestion significantly increased salivary caffeine levels (p < 0.001; η P 2 = 0.75) and, overall, resulted in improved 5 km time trial performance (p < 0.001; η P 2 = 0.23). Performance following COF (482 ± 51 s) was faster than PLA (491 ± 53 s; p = 0.002; d = 0.17) and CON (487 ± 52 s; p =0.002; d = 0.10) trials, with men and women both improving by approximately 9 seconds and 6 seconds following coffee ingestion compared with placebo and control, respectively. However, no differences were observed between CON and PLA (p = 0.321; d = 0.08). In conclusion, ingesting coffee providing 3 mg·kg-1 of caffeine increased salivary caffeine levels and improved 5 km cycling time trial performance in men and women by a similar magnitude.

Are caffeine’s performance-enhancing effects partially driven by its bitter taste?

Article

Jul 2019
MED HYPOTHESES

Craig Pickering

Caffeine is a well-established ergogenic aid, with its performance-enhancing effects replicated across a variety of exercise types. Caffeine exerts its performance-benefits through many mechanisms, including acting as an adenosine receptor antagonist, and serving to reduce sensations of fatigue and pain. One potential mechanism that is currently underexplored is whether caffeine’s bitter taste mediates some of its ergogenic effects, which is discussed in this article. Previous research has demonstrated that bitter tastants have the ability to enhance performance, and this effect is mediated by bitter taste receptors in the mouth and gastrointestinal tract. Additionally, the ability to detect bitter tastes is subject to individual variation, raising the potential that the demonstrated inter-individual response to a standardised caffeine dose is potentially driven by differences in taste response. Finally, it appears that some of caffeine’s performance-enhancing effects are driven by expectancy. As bitter taste may serve as a signal that caffeine has been ingested, it is possible that some of the expectancy effects of caffeine ingestion are driven by its bitter taste. These aspects all have potentially important implications for future research, as well as for how athletes and coaches utilise caffeine around competition, both of which are explored in depth here.

Caffeine and Exercise: What Next?

Article

Full-text available

Jul 2019
SPORTS MED

Caffeine is a widely utilized performance-enhancing supplement used by athletes and non-athletes alike. In recent years, a number of meta-analyses have demonstrated that caffeine’s ergogenic effects on exercise performance are well-established and well-replicated, appearing consistent across a broad range of exercise modalities. As such, it is clear that caffeine is an ergogenic aid—but can we further explore the context of this ergogenic aid in order to better inform practice? We propose that future research should aim to better understand the nuances of caffeine use within sport and exercise. Here, we propose a number of areas for exploration within future caffeine research. These include an understanding of the effects of training status, habitual caffeine use, time of day, age, and sex on caffeine ergogenicity, as well as further insight into the modifying effects of genotype. We also propose that a better understanding of the wider, non-direct effects of caffeine on exercise, such as how it modifies sleep, anxiety, and post-exercise recovery, will ensure athletes can maximize the performance benefits of caffeine supplementation during both training and competition. Whilst not exhaustive, we hope that the questions provided within this manuscript will prompt researchers to explore areas with the potential to have a large impact on caffeine use in the future.

Wake up and smell the coffee: caffeine supplementation and exercise performance—An umbrella review of 21 published meta-analyses

Article

Full-text available

Apr 2019

Objective To systematically review, summarise, and appraise findings of published meta-analyses that examined the effects of caffeine on exercise performance. Design Umbrella review. Data sources Twelve databases. Eligibility criteria for selecting studies Meta-analyses that examined the effects of caffeine ingestion on exercise performance. Results Eleven reviews (with a total of 21 meta-analyses) were included, all being of moderate or high methodological quality (assessed using the AMSTAR 2 checklist). In the meta-analyses, caffeine was ergogenic for aerobic endurance, muscle strength, muscle endurance, power, jumping performance, and exercise speed. However, not all analyses provided a definite direction for the effect of caffeine when considering the 95% prediction interval. Using the GRADE criteria the quality of evidence was generally categorised as moderate (with some low to very low quality of evidence). Most individual studies included in the published meta-analyses were conducted among young men. Summary/Conclusion Synthesis of the currently available meta-analyses suggest that caffeine ingestion improves exercise performance in a broad range of exercise tasks. Ergogenic effects of caffeine on muscle endurance, muscle strength, anaerobic power, and aerobic endurance were substantiated by moderate quality of evidence coming from moderate-to-high quality systematic reviews. For other outcomes, we found moderate quality reviews that presented evidence of very low or low quality. It seems that the magnitude of the effect of caffeine is generally greater for aerobic as compared with anaerobic exercise. More primary studies should be conducted among women, middle-aged and older adults to improve the generalisability of these findings.

The effects of polyphenols and other bioactives on human health

Article

Full-text available

Feb 2019

Although deficiencies in polyphenol intake do not result in specific deficiency diseases, adequate intake of polyphenols could confer health benefits, especially with regard to chronic diseases. Tea, cocoa, fruits, and berries, as well as vegetables, are rich in polyphenols. Flavan-3-ols from cocoa have been found to be associated with a reduced risk of stroke, myocardial infarction, and diabetes, as well as improvements in lipids, endothelial-dependent blood flow and blood pressure, insulin resistance, and systemic inflammation. The flavonoid quercetin and the stilbene resveratrol have also been associated with cardiometabolic health. Although polyphenols have been associated with improved cerebral blood flow, evidence of an impact on cognition is more limited. The ability of dietary polyphenols to produce clinical effects may be due, at least in part, to a bi-directional relationship with the gut microbiota. Polyphenols can impact the composition of the gut microbiota (which are independently associated with health benefits), and gut bacteria metabolize polyphenols into bioactive compounds that produce clinical benefits. Another critical interaction is that of polyphenols with other phytochemicals, which could be relevant to interpreting the health parameter effects of polyphenols assayed as purified extracts, whole foods, or whole food extracts.

Low Doses of Caffeine: Enhancement of Physical Performance in Elite Adolescent Male Soccer Players

Article

Full-text available

Oct 2018

Context:: Large doses of ~6 mg·kg-1 body mass have improved performance during intermittent running, jumping, and agility protocols. However, there are sparse data on low doses of caffeine, especially in elite adolescent soccer players. Method:: Fifteen elite youth soccer players (177.3±4.8 cm, 66.9±7.9 kg and 16±1 y) participated in the study, consuming 1, 2, or 3 mg·kg-1 caffeine in a gelatin capsule or a 2-mg·kg-1 placebo in a single-blind, randomized, crossover study design. Testing consisted of a 20-m sprint, arrowhead agility (change of direction [CoD] right or left), countermovement jump (CMJ), and Yo-Yo Intermittent Recovery Test Level-1 (Yo-Yo IR1). Post-exercise CMJ performance was assessed as participants exited the Yo-Yo IR1. Data were analyzed using a Bayesian multilevel regression model to provide explained variance and probabilities of improvement (p=%). Results:: 3 mg·kg-1 caffeine presented the highest probabilities of change compared with placebo across a range of tests (mean ± SD, p= %). Times for 20-m sprint were 3.15±0.10s vs 3.18±0.09s (p=73%), CoD-R times were 8.43±0.24s vs 8.55±0.25s (p=99%), CoD-L times were 8.44±0.22s vs 8.52±0.18s (p=85%), Yo-Yo IR1 distance was 2440±531m vs 2308±540m (p=15%), and preexercise CMJ height was 41.6±7.2cm vs 38±8.5cm (p=96%). Postexercise CMJ was higher with 3 mg·kg-1 than with placebo (42.3±8cm vs 36.6±8cm [p=100%]). Doses of 1 or 2 mg·kg-1 caffeine also demonstrated the ability to enhance performance but were task dependent. Conclusion:: Low doses of caffeine improve performance but are dose and task dependent. A dose of 3 mg·kg-1 caffeine improved performance across the majority of tests with potential to further improve postexercise CMJ height.

Echocardiographic Assessment of Right Ventricle Dimensions and Function After Exposure to Extreme Altitude: Is an Expedition to 8000 m Hazardous for Right Ventricular Function?

Article

Aug 2017
HIGH ALT MED BIOL

Kurdziel, Marta, Jarosław Wasilewski, Karolina Gierszewska, Anna Kazik, Gracjan Pytel, Jacek Wacławski, Adam Krajewski, Anna Kurek, Lech Poloński, and Mariusz Gąsior. Echocardiographic assessment of right ventricle dimensions and function after exposure to extreme altitude: Is an expedition to 8000 m hazardous for right ventricular function? High Alt Med Biol 00:000-000, 2017.-Although the right ventricle (RV) is under great hypoxic stress at altitude, still little is known what happens to the RV after descent. The aim of this study was to evaluate RV dimensions and function after exposure to extreme altitude. Therefore, echocardiographic examination was performed according to a protocol that focused on the RV in 11 healthy subjects participating in an expedition to K2 (8611 m) or Broad Peak (BP, 8051 m). In comparison to measurements before the expedition, after 7-8 weeks of sojourn above 2300 meters with the aim of climbing K2 and BP, the RV Tei index increased (0.5 ± 0.1 vs. 0.4 ± 0.1; p = 0.028), and RV free wall longitudinal systolic strain (RVFWLSS) decreased (-23.1% ± 2.7% vs. -25.9% ± 2.4%; p = 0.043). Decrease in peak systolic strain and strain rate was observed in the basal and mid segments of the RV free wall (respectively: -24.4% ± 4.4% vs. -30.9% ± 6.5%; -1.4 ± 0.3 s(-1) vs. -1.8 ± 0.3 s(-1); -28.7% ± 3.9% vs. -34% ± 3.3%; -1.5 ± 0.2 s(-1) vs. -1.9 ± 0.3 s(-1); p for all <0.05). The linear RV dimensions, the proximal and distal RV outflow tracks, increased (respectively: 31.3 ± 4 mm vs. 29.2 ± 3 mm, p = 0.025; 27 ± 2.7 mm vs. 24.8 ± 3 mm, p = 0.012). We found that exposure to extreme altitude may cause RV dilatation and a decrease in RV performance. The Tei index and RVFWLSS are sensitive performance indices to detect changes in RV function after the exposure to hypoxic stress. The observed alterations seem to be a manifestation of physiological adaptation to high-altitude condition in healthy individuals.

Effect of decaffeinated coffee on function and nucleotide metabolism in kidney

Article

Full-text available

Feb 2018
MOL CELL BIOCHEM

Little is known about the effects of coffee that are not related to the presence of caffeine. The aim of the study was to analyse changes in kidney function and nucleotide metabolism related to high intake of decaffeinated coffee. Mice consumed decaffeinated coffee extract for two weeks. Activities of AMP deaminase, ecto5′-nucleotidase, adenosine deaminase, purine nucleoside phosphorylase were measured in kidney cortex and medulla by analysis of conversion of substrates into products using HPLC. Concentration of nucleotides in kidney cortex, kidney medulla and serum were estimated by HPLC. Activity of ecto5′-nucleotidase increased from 0.032 ± 0.006 to 0.049 ± 0.014 nmol/mg tissue/min in kidney cortex of mice administered high-dose decaffeinated coffee (HDC) together with increase in cortex adenosine concentration and decrease in plasma creatinine concentration. HDC leads to increased activity of ecto5′-nucleotidase in kidney cortex that translates to increase in concentration of adenosine. Surprisingly this caused improved kidney excretion function.

Caffeine ingestion acutely enhances muscular strength and power but not muscular endurance in resistance-trained men

Article

Full-text available

May 2017
EUR J SPORT SCI

The goal of this randomized, double-blind, cross-over study was to assess the acute effects of caffeine ingestion on muscular strength and power, muscular endurance, rate of perceived exertion (RPE), and pain perception (PP) in resistance-trained men. Seventeen volunteers (mean ± SD: age = 26 ± 6 years, stature = 182 ± 9 cm, body mass = 84 ± 9 kg, resistance training experience = 7 ± 3 years) consumed placebo or 6 mg kg −1 of anhydrous caffeine 1 h before testing. Muscular power was assessed with seated medicine ball throw and vertical jump exercises, muscular strength with one-repetition maximum (1RM) barbell back squat and bench press exercises, and muscular endurance with repetitions of back squat and bench press exercises (load corresponding to 60% of 1RM) to momentary muscular failure. RPE and PP were assessed immediately after the completion of the back squat and bench press exercises. Compared to placebo, caffeine intake enhanced 1RM back squat performance (+2.8%; effect size [ES] = 0.19; p = .016), which was accompanied by a reduced RPE (+7%; ES = 0.53; p = .037), and seated medicine ball throw performance (+4.3%, ES = 0.32; p = .009). Improvements in 1RM bench press were not noted although there were significant (p = .029) decreases in PP related to this exercise when participants ingested caffeine. The results point to an acute benefit of caffeine intake in enhancing lower-body strength, likely due to a decrease in RPE; upper-, but not lower-body power; and no effects on muscular endurance, in resistance-trained men. Individuals competing in events in which strength and power are important performance-related factors may consider taking 6 mg kg −1 of caffeine pre-training/competition for performance enhancement.

Caffeine Supplementation as an Ergogenic Aid for Muscular Strength and Endurance: A Recommendation for Coaches and Athletes - Review

Article

Full-text available

Oct 2016

Caffeine (1, 3, 7-trimethylxanthine) which can be ubiquitously found in energy drinks, sodas, coffee, and supplements, is one of the principal legal drugs consumed worldwide. Caffeine based ergogenic aids are utilized prolifically within training and competition for an ergogenic benefit to enhance sporting performance by both recreational and elite athletes. The evidence of caffeine's ability to enhance endurance performance is well established, however, evidence of an ergogenic benefit for muscular endurance and strength-based tasks is limited. Moreover, the limited evidence for caffeine's ergogenic benefit in muscular endurance and strength is equivocal, and therefore, practical recommendations for the implementation of caffeine supplementation in training and competition for coaches, and practitioners is difficult. Indeed, it is currently not known if, and how caffeine may improve muscular endurance and/or strength based tasks. Variability in the findings could be due to several factors including muscles tested, participant characteristics, exercise protocol, type and dose of caffeine used. This brief review will discuss the current literature relating to the potential efficacy of caffeine to enhance muscular endurance and strength based performance, and provides evidence based recommendations for athletes and coaches to implement. attempt to aid recreational performance [2]. This has promoted an increase in the sale of caffeine based supplements and energy drinks [3] and these readily available forms of the drug are now typically consumed by younger populations and even those not participating in sport or exercise [4]. In a sport and exercise context, caffeine has been consistently shown to aid a variety of endurance based tasks [5-7] with significant enhancements in cycling [8,9], swimming [10] and rowing [11] performance all being reported. On the other hand, both supporting [12-18] and contradicting [19-23] research has been published in terms of muscular endurance. Furthermore, the evidence of caffeine improving muscular strength is a concept that produces additional equivocal conclusions. Few studies have reported increases in one repetition maximum (1RM) post caffeine supplementation in comparison to placebo [21,23] and control [24] trial with a superior number reporting no change [20,25,26]. Caffeine's primary mechanistic process likely occurs through the antagonising of adenosine [27]. This process is achieved by caffeine binding to adenosine receptors, reducing adenosine's ability to slow neural activity, reduce arousal, and induce sleep [28]. Further rewards from caffeine's effect on adenosine receptors include enhanced neurotransmitter release, increased firing rates, and amplified spontaneous and evoked potentials [29]. Caffeine has also been shown to alter metabolic substrate utilization [9] and provide enhanced fat oxidation and consequential glycogen sparing [30]. Alterations to pain perception following caffeine supplementation have also been reported [31] most likely due to enhanced secretion of β-endorphins [32]. More specifically to strength performance, possible mechanisms also include increased muscle activation [33], motor unit recruitment [34], and enhanced excitation contraction coupling [35]. It should be noted, that it is beyond the scope of this review to provide a comprehensive overview of the mechanisms of caffeine. The primary purpose of this review is to provide in depth analysis of the evidence relating to the use of caffeine in muscular endurance and strength based exercise, and provide coaches and athletes, at both elite and recreational level, with recommendations for the use of caffeine with regards to muscular strength and muscular endurance. For a complementary, wider-ranged review of all current literature, readers is direct to other published review articles [36,37] and a meta-analysis [38].

Drug Use and Misuse in the Mountains: A UIAA MedCom Consensus Guide for Medical Professionals

Article

Sep 2016
HIGH ALT MED BIOL

Results: Prophylactic, therapeutic, and recreational uses of drugs relevant to mountaineering are presented with an assessment of their risks and benefits. Conclusions: If using drugs not regulated by the World Anti-Doping Agency (WADA), individuals have to determine their own personal standards for enjoyment, challenge, acceptable risk, and ethics. No system of drug testing could ever, or should ever, be policed for recreational climbers. Sponsored climbers or those who climb for status need to carefully consider both the medical and ethical implications if using drugs to aid performance. In some countries (e.g., Switzerland and Germany), administrative systems for mountaineering or medication control dictate a specific stance, but for most recreational mountaineers, any rules would be unenforceable and have to be a personal decision, but should take into account the current best evidence for risk, benefit, and sporting ethics.

Coffee and Caffeine Ingestion Have Little Effect on Repeated Sprint Cycling in Relatively Untrained Males

Article

Full-text available

Aug 2016

The present study investigated the effect of ingesting caffeine-dose-matched anhydrous caffeine or coffee on the performance of repeated sprints. Twelve recreationally active males (mean ± SD age: 22 ± 2 years, height: 1.78 ± 0.07 m, body mass: 81 ± 16 kg) completed eighteen 4 s sprints with 116 s recovery on a cycle ergometer on four separate occasions in a double-blind, randomised, counterbalanced crossover design. Participants ingested either 3 mg·kg−1 of caffeine (CAF), 0.09 g·kg−1 coffee, which provided 3 mg·kg−1 of caffeine (COF), a taste-matched placebo beverage (PLA), or a control condition (CON) 45 min prior to commencing the exercise protocol. Peak and mean power output and rating of perceived exertion (RPE) were recorded for each sprint. There were no significant differences in peak power output (CAF: 949 ± 199 W, COF: 949 ± 174 W, PLA: 971 ± 149 W and CON: 975 ± 170 W; p = 0.872; η P 2 = 0.02) or mean power output (CAF: 873 ± 172 W, COF: 862 ± 44 W, PLA: 887 ± 119 W and CON: 892 ± 143 W; p = 0.819; η P 2 = 0.03) between experimental conditions. Mean RPE was similar for all trials (CAF: 11 ± 2, COF: 11 ± 2, PLA: 11 ± 2 and CON: 11 ± 2; p = 0.927; η P 2 = 0.01). Neither the ingestion of COF or CAF improved repeated sprint cycling performance in relatively untrained males.

Comment on: “Caffeine and Exercise: What Next?”

Article

Mar 2020

Effect of caffeine supplementation on exercise performance, power, markers of muscle damage, and perceived exertion in trained CrossFit men: a randomized, double-blind, placebo-controlled crossover trial

Article

Oct 2019
J SPORT MED PHYS FIT

Background: Caffeine is a popular nutritional supplement among athletes. It is frequently used as an ergogenic aid to improve physical performance, delay fatigue, and increase muscle power. However, these effects have not been tested in CrossFit athletes. The aim of this study was to evaluate the effects of acute caffeine supplementation on workout performance, power, markers of muscle damage, and soreness in trained CrossFit men. Methods: Nine men (28 ± 2 years) with experience in CrossFit (2 ± 0.3 years) were investigated in a randomized, double-blind, placebo-controlled crossover trial, with a 7-day washout between treatment periods. The athletes received anhydrous caffeine (CAF: 6 mg / kg body mass) or placebo (PLA) 60 minutes before a CrossFit workout with tasks that involved muscle strength, power, gymnastic movements, and metabolic conditioning. Blood samples were collected for creatine kinase (CK), C-reactive protein, and glucose determination. Workout performance, rating of perceived exertion (RPE), delayed-onset muscle soreness (DOMS), muscle strength (handgrip strength) and power (bench throw, jump squat and countermovement jump) were also evaluated. Results: CAF resulted in higher glucose concentration after workout compared to PLA (+3.2 mmol/L, 95%CI: 2.1 to 4.3 vs +1.5, 95%CI: -0.1 to 3.0 mmol/L, p = 0.01). No differences were found between treatments in workout performance, CK, DOMS, RPE, muscle power and strength. Conclusions: Acute CAF supplementation did not alter performance, markers of muscle damage, power, and RPE in trained CrossFit men.

Düşük Doz Kafeinli Kahvenin Fiziksel Olarak Aktif Erkeklerde Anaerobik Güce Etkisi

Article

Full-text available

Jan 2017

Raci Karayigit

Coffee Ingestion Enhances One-Mile Running Race Performance

Article

Full-text available

Nov 2017

Purpose: Caffeine, often in the form of coffee, is frequently supplemented by athletes in an attempt to facilitate improved performance during exercise. The aim of the present study was to investigate the effectiveness of coffee ingestion as an ergogenic aid prior to a one-mile (1609 m) race. Methods: In a double-blind, randomised, crossover, placebo-controlled design 13 trained male runners completed a one-mile race 60 minutes following the ingestion of 0.09 g·kg(-1) coffee (COF), 0.09 g·kg(-1) decaffeinated coffee (DEC), or a placebo (PLA). All trials were dissolved in 300 ml of hot water. Results: The race completion time was 1.3% faster following the ingestion of COF (04:35:37 ± 00:10:51 mm·ss) compared with DEC (04:39:14 ± 00:11:21 mm·ss; P=0.018; 95%CI: -0.11, -0.01; d=0.32) and 1.9% faster compared with PLA (04:41:00 ± 00:09:57 mm:ss; P=0.006; 95%CI: -0.15, -0.03; d=0.51). A large trial and time interaction for salivary caffeine concentration was observed (P<0.001; η(2)P=0.69) with a very large increase (6.40 ± 1.57 μg·ml(-1), 95%CI: 5.5, 7.3; d=3.86) following the ingestion of COF. However, only a trivial difference between DEC and PLA was observed (P=0.602; 95%CI: -0.09, 0.03; d=0.17). Furthermore, only trivial differences for blood glucose (P=0.839; η(2)P=0.02) and lactate (P=0.096; η(2)P=0.18), and maximal heart rate (P=0.286; η(2)P=0.13) were observed between trials. Conclusions: The results of the present study show that 60 minutes after ingesting 0.09 g·kg(-1) of caffeinated coffee one-mile race performance was enhanced by 1.9% and 1.3% compared with placebo and decaffeinated coffee respectively, in trained male runners.

An Overview on Nitric Oxide and Energy Metabolism

Chapter

Full-text available

Aug 2017

Nitric oxide (NO) is a gaseous signaling molecule with a short half-life that's known to exert its biological functions through cyclic guanosine monophosphate. In our system, nitric oxide is produced by nitric oxide synthase enzymes, which use substrates l-arginine, reduced nicotinamide adenine dinucleotide phosphate (NADPH), and oxygen by producing citrulline, nicotinamide adenine dinucleotide phosphate (NADP⁺), and NO. Nitric oxide can react with superoxide to produce peroxynitrite (ONOO?), which can cause irreversible modification and inhibition of different biological molecules, including mitochondrial membrane complexes and antioxidant defense enzymes through oxidizing reactions. This chapter focuses on the direct and indirect role of NO in terms of energy metabolism. Nitric oxide in this context governs and regulates metabolism, heat production, and body composition, which overall change the tissue distribution of oxygen, adenosine triphosphate production, blood flow, glucose utilization, and supply of other nutrients by resulting in altered tissue functions and physical activities.

Beneficial Roles of Caffeine in Sports Nutrition and Beverage Formulations

Chapter

Aug 2017

Dawn Anderson

Caffeine is found in many foods, beverages, and over-the-counter drugs. Energy drink consumption increased dramatically from 2001 to 2010, and energy shots are the fastest-growing segment of the energy drink category. The ingestion of caffeine in the form of coffee or anhydrous caffeine has consistently been shown to improve performance in time to exhaustion exercises performed at submaximal intensities, although the ergogenic benefits for anaerobic activities are less clear. Caffeine-containing energy drinks improve performance in endurance exercises, muscular strength, and endurance activities, jumping, and sport-specific actions. Performance may be affected by the ingestion of other substances such as taurine contained in these energy drinks, in addition to caffeine. Factors that must be considered when interpreting the effectiveness of caffeine as an ergogenic aid are timing of administration, abstinence period, dosage, and training status of the individual.

Impact of Dietary Antioxidants on Sport Performance: A Review

Article

Full-text available

Mar 2015
SPORTS MED

Many athletes supplement with antioxidants in the belief this will reduce muscle damage, immune dysfunction and fatigue, and will thus improve performance, while some evidence suggests it impairs training adaptations. Here we review the effect of a range of dietary antioxidants and their effects on sport performance, including vitamin E, quercetin, resveratrol, beetroot juice, other food-derived polyphenols, spirulina and N-acetylcysteine (NAC). Older studies suggest vitamin E improves performance at altitude, with possible harmful effects on sea-level performance. Acute intake of vitamin E is worthy of further consideration, if plasma levels can be elevated sufficiently. Quercetin has a small beneficial effect for exercise of longer duration (>100 min), but it is unclear whether this benefits athletes. Resveratrol benefits trained rodents; more research is needed in athletes. Meta-analysis of beetroot juice studies has revealed that the nitrate component of beetroot juice had a substantial but unclear effect on performance when averaged across athletes, non-athletes and modes of exercise (single dose 1.4 ± 2.0 %, double dose 0.5 ± 1.9 %). The effect of addition of polyphenols and other components to beetroot juice was trivial but unclear (single dose 0.4 ± 3.2 %, double dose -0.5 ± 3.3 %). Other food-derived polyphenols indicate a range of performance outcomes from a large improvement to moderate impairment. Limited evidence suggests spirulina enhances endurance performance. Intravenous NAC improved endurance cycling performance and reduced muscle fatigue. On the basis of vitamin E and NAC studies, acute intake of antioxidants is likely to be beneficial. However, chronic intakes of most antioxidants have a harmful effect on performance.

The effect of an acute antioxidant supplementation compared with placebo on performance and hormonal response during a high volume resistance training session

Article

Full-text available

Mar 2014
Sports Nutr Rev J

Antioxidant supplementation is known to increase human endogenous antioxidant (AOX) capacity providing a means of blunting exercise induced reactive oxygen species (ROS). The purpose of this study was to compare the effects of a single acute dose of an AOX (vs blinded placebo) on muscle contractile performance and hormonal responses to a single bout of lower limb 'hypertrophic' resistance training (RT). Fifteen resistance trained subjects (age 23 +/- 4 years: body mass 86 +/- 6 kg) volunteered to participate in the study. Each subject attended the laboratory on three occasions, firstly to determine three repetition maximum (3-RM) isotonic strength in the back squat and perform a familiarisation of the experimental task. On the second/third visits subjects completed the hypertrophic training session (HTS) which consisted of six sets of 10 repetitions of 70% of a predicted 1 RM load (kg). Four hours prior to the HTS the subjects consumed 2 ml[bullet operator]kg-1 total body mass of either the placebo mixture or AOX supplement in a randomised order. Work completed during the strength training session was completed with equipment that had an integrated linear force transducer (Gymaware system, Kinetic Performance Technology, Canberra, Australia). During the placebo trials concentric mean power significantly (p < 0.05) decreased from sets 1-6. Accumulated power output during the AOX HTS was 6746 +/- 5.9 W which was significantly greater compared to the placebo HTS of 6493 +/- 17.1 W (p < 0.05, ES'r = 0.99). Plasma growth hormone (GH) concentration was significantly less immediately following AOX supplementation (6.65 +/- 1.84 vs 16.08 +/- 2.78 ng[bullet operator]ml-1; p < 0.05, ES'r = 0.89). This study demonstrates ingestion of an AOX cocktail prior to a single bout of resistance training improved muscle contractile performance and modulated the GH response following completion of the resistance exercise. Future studies should explore the mechanisms associated with the performance modification and specific muscle adaptations to AOX supplementation in conjunction with heavy RT.

Caffeine and Anaerobic Performance

Article

Full-text available

Oct 2009

The effect caffeine elicits on endurance performance is well founded. However, comparatively less research has been conducted on the ergogenic potential of anaerobic performance. Some studies showing no effect of caffeine on performance used untrained subjects and designs often not conducive to observing an ergogenic effect. Recent studies incorporating trained subjects and paradigms specific to intermittent sports activity support the notion that caffeine is ergogenic to an extent with anaerobic exercise. Caffeine seems highly ergogenic for speed endurance exercise ranging in duration from 60 to 180 seconds. However, other traditional models examining power output (i.e. 30-second Wingate test) have shown minimal effect of caffeine on performance. Conversely, studies employing sport-specific methodologies (i.e. hockey, rugby, soccer) with shorter duration (i.e. 4–6 seconds) show caffeine to be ergogenic during high-intensity intermittent exercise. Recent studies show caffeine affects isometric maximal force and offers introductory evidence for enhanced muscle endurance for lower body musculature. However, isokinetic peak torque, one-repetition maximum and muscular endurance for upper body musculature are less clear. Since relatively few studies exist with resistance training, a definite conclusion cannot be reached on the extent caffeine affects performance. It was previously thought that caffeine mechanisms were associated with adrenaline (epinephrine)-induced enhanced free-fatty acid oxidation and consequent glycogen sparing, which is the leading hypothesis for the ergogenic effect. It would seem unlikely that the proposed theory would result in improved anaerobic performance, since exercise is dominated by oxygen-independent metabolic pathways. Other mechanisms for caffeine have been suggested, such as enhanced calcium mobilization and phosphodiesterase inhibition. However, a normal physiological dose of caffeine in vivo does not indicate this mechanism plays a large role. Additionally, enhanced Na+/K+ pump activity has been proposed to potentially enhance excitation contraction coupling with caffeine. A more favourable hypothesis seems to be that caffeine stimulates the CNS. Caffeine acts antagonistically on adenosine receptors, thereby inhibiting the negative effects adenosine induces on neurotransmission, arousal and pain perception. The hypoalgesic effects of caffeine have resulted in dampened pain perception and blunted perceived exertion during exercise. This could potentially have favourable effects on negating decreased firing rates of motor units and possibly produce a more sustainable and forceful muscle contraction. The exact mechanisms behind caffeine’s action remain to be elucidated.

Effect of caffeine ingestion on one-repetition maximum muscular strength

Article

Full-text available

Jan 2008
EUR J APPL PHYSIOL

Multiple studies corroborate the ergogenic properties of caffeine (CAF) for endurance performance, yet fewer investigations document the efficacy of acute caffeine intake for intense, short-term exercise. The aim of the study was to determine the ergogenic potential of caffeine during testing of muscular strength and endurance. Twenty-two resistance-trained men ingested CAF (6 mg/kg) or placebo (PL) 1 h pre-exercise in a randomized, double-blind crossover design. They refrained from caffeine intake and strenuous exercise 48 and 24 h, respectively, pre-visit. Initially, resting heart rate and blood pressure were obtained followed by one-repetition maximum (1-RM) testing on the barbell bench press and leg press. Upon determination of 1-RM, participants completed repetitions to failure at 60%1-RM. Heart rate, blood pressure, and rating of perceived exertion (RPE) were measured after the final repetition. Compared to PL, there was no effect (P > 0.05) of caffeine on muscular strength, as 1-RM bench press (116.4 +/- 23.6 kg vs. 114.9 +/- 22.8 kg) and leg press (410.6 +/- 92.4 kg vs. 394.8 +/- 95.4 kg) were similar. Total weight lifted during the 60% 1-RM trial was 11 and 12% higher for the bench press and leg press with caffeine compared to placebo, yet did not reach significance. RPE was similar at the end of resistance exercise with CAF vs. PL. Acute caffeine intake does not significantly alter muscular strength or endurance during intense bench press or leg press exercise, yet the practical importance of the increased muscular endurance remains to be explored.

Multiple dose pharmacokinetics of caffeine administered in chewing gum to normal healthy volunteers

Article

Dec 2005

The purpose of this study was to examine the pharmacokinetics of three doses of caffeine administered as Stay Alert chewing gum in a multiple dose regimen. A double-blind, parallel randomized, four-treatment study design was employed. The treatment groups were: 50, 100 and 200 mg caffeine and placebo. Subjects were 48 (n = 12 per group), healthy, non-smoking, males and females who had abstained from caffeine ingestion for at least 20 h prior to dosing, who were randomly assigned to the treatment groups. Caffeine was administered at 2,400, 0200 and 0400 h depending on the treatment group. Blood samples were collected pre-dose and at 5, 15, 30, 45, 60, 75, 90 and 105 min after each caffeine dose. Samples were also collected at 7.5, 8.5 and 18 h after the last dose of caffeine. Plasma caffeine levels were analysed by a validated UV-HPLC method. The mean T(max) after the third dosing ranged from 0.37 to 1.12 h. C(max) for 50, 100 and 200 mg was 2.69, 3.45 and 6.33 mg/l, respectively. AUC(inf) for 50, 100 and 200 mg group was 33.2, 46.94 and 86.94 mg/l * h, respectively. AUC(inf) values suggested a dose proportionate increase. Dose normalized C(max) and AUC(0-tau) values across doses were not significantly different, suggesting linearity was maintained after multiple doses of the Stay Alert chewing gum. There were no group related differences in elimination. The results suggest that caffeine administered in the gum formulation (Stay Alert chewing gum) via a multiple dosing regimen provides an effective and convenient means of maintaining effective concentrations of caffeine that would in some operational scenarios be desirable for maintaining alertness and performance in sleep deprived individuals.

Effect Of Coffee And Caffeine Ingestion On Resistance Exercise Performance

Abstract

No full-text available

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