Effects of coffee and caffeine anhydrous on strength and sprint performance

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

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

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

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.

Multi-Ingredient Preworkout Supplementation Compared With Caffeine and a Placebo Does Not Improve Repetitions to Failure in Resistance-Trained Women

There has been an increase in the use of commercially available multi-ingredient preworkout supplements (MIPS); however, there are inconsistencies regarding the efficacy of MIPS in resistance-trained women.

PURPOSE

To determine the effect of varying doses of MIPS compared with caffeine only (C) and a placebo (PL) on resistance-training performance in trained women.

METHODS

Ten women (21.5 [2.3] y) completed 1-repetition-maximum tests at baseline for leg press and bench press. A within-group, double-blind, and randomized design was used to assign supplement drinks (ie, PL, C, MIPS half scoop [MIPS-H], and MIPS full scoop [MIPS-F]). Repetitions to failure were assessed at 75% and 80% to 85% of 1-repetition maximum for bench and leg press, respectively. Total performance volume was calculated as load × sets × repetitions for each session. Data were analyzed using a 1-way repeated-measures analysis of variance and reported as means and SDs.

RESULTS

There were no differences in repetitions to failure for bench press (PL: 14.4 [3.2] repetitions, C: 14.4 [2.9] repetitions, MIPS-H: 14.2 [2.6] repetitions, MIPS-F: 15.1 [3.1] repetitions; P = .54) or leg press (PL: 13.9 [7.8] repetitions, C: 10.8 [5.9] repetitions, MIPS-H: 13.1 [7.1] repetitions, MIPS-F: 12.4 [10.7] repetitions; P = .44). Furthermore, there were no differences in total performance volume across supplements for bench press (PL: 911.2 [212.8] kg, C: 910.7 [205.5] kg, MIPS-H: 913.6 [249.3] kg, MIPS-F: 951.6 [289.6] kg; P = .39) or leg press (PL: 4318.4 [1633.6] kg, C: 3730.0 [1032.5] kg, MIPS-H: 4223.0 [1630.0] kg, MIPS-F: 4085.5 [2098.3] kg; P = .34).

CONCLUSIONS

Overall, our findings suggest that caffeine and MIPS do not provide ergogenic benefits for resistance-trained women in delaying muscular failure.

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

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

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.

Effects of Caffeinated Coffee on Cross-Country Cycling Performance in Recreational Cyclists

The ergogenic effects of acute caffeine intake on endurance cycling performance lasting ~1 h have been well documented in controlled laboratory studies. However, the potential benefits of caffeine supplementation in cycling disciplines such as cross-country/mountain biking have been rarely studied. In cross-country cycling, performance is dependent on endurance capacity, which may be enhanced by caffeine, but also on the technical ability of the cyclist to overcome the obstacles of the course. So, it is possible that the potential benefits of caffeine are not translated to cross-country cycling. The main objective of this study was to investigate the effects of acute caffeine intake, in the form of coffee, on endurance performance during a cross-country cycling time trial. Eleven recreational cross-country cyclists (mean ± SD: age: 22 ± 3 years; nine males and two females) participated in a single-blinded, randomised, counterbalanced and crossover experiment. After familiarisation with the cross-country course, participants completed two identical experimental trials after the ingestion of: (a) 3.00 mg/kg of caffeine in the form of soluble coffee or (b) 0.04 mg/kg of caffeine in the form of decaffeinated soluble coffee as a placebo. Drinks were ingested 60 min before performing a 13.90 km cross-country time trial over a course with eight sectors of varying technical difficulty. The time to complete the trial and the mean and the maximum speed were measured through Global Positioning System (GPS) technology. Heart rate was obtained through a heart rate monitor. At the end of the time trial, participants indicated their perceived level of fatigue using the traditional Borg scale. In comparison to the placebo, caffeine intake in the form of coffee significantly reduced the time to complete the trial by 4.93 ± 4.39% (43.20 ± 7.35 vs. 41.17 ± 6.18 min; p = 0.011; effect size [ES] = 0.300). Caffeine intake reduced the time to complete four out of eight sectors with different categories of technical difficulty (p ≤ 0.010; ES = 0.386 to 0.701). Mean heart rate was higher with caffeine (169 ± 6 vs. 162 ± 13 bpm; p = 0.046; ES = 0.788) but the rating of perceived exertion at the end of the trial was similar with caffeinated coffee than with the placebo (16 ± 1 vs. 16 ± 2 a.u.; p = 0.676; ES = 0.061). In conclusion, the intake of 3 mg/kg of caffeine delivered via soluble coffee reduced the time to complete a cross-country cycling trial in recreational cyclists. These results suggest that caffeine ingested as coffee may be an ergogenic substance for cross-country cycling.

Maximal Number of Repetitions at Percentages of the One Repetition Maximum: A Meta-Regression and Moderator Analysis of Sex, Age, Training Status, and Exercise

The maximal number of repetitions that can be completed at various percentages of the one repetition maximum (1RM) [REPS ~ %1RM relationship] is foundational knowledge in resistance exercise programming. The current REPS ~ %1RM relationship is based on few studies and has not incorporated uncertainty into estimations or accounted for between-individuals variation. Therefore, we conducted a meta-regression to estimate the mean and between-individuals standard deviation of the number of repetitions that can be completed at various percentages of 1RM. We also explored if the REPS ~ %1RM relationship is moderated by sex, age, training status, and/or exercise. A total of 952 repetitions-to-failure tests, completed by 7289 individuals in 452 groups from 269 studies, were identified. Study groups were predominantly male (66%), healthy (97%), < 59 years of age (92%), and resistance trained (60%). The bench press (42%) and leg press (14%) were the most commonly studied exercises. The REPS ~ %1RM relationship for mean repetitions and standard deviation of repetitions were best described using natural cubic splines and a linear model, respectively, with mean and standard deviation for repetitions decreasing with increasing %1RM. More repetitions were evident in the leg press than bench press across the loading spectrum, thus separate REPS ~ %1RM tables were developed for these two exercises. Analysis of moderators suggested little influences of sex, age, or training status on the REPS ~ %1RM relationship, thus the general main model REPS ~ %1RM table can be applied to all individuals and to all exercises other than the bench press and leg press. More data are needed to develop REPS ~ %1RM tables for other exercises.

Extrapolating the Coffee and Caffeine (1,3,7-Trimethylxanthine) Effects on Exercise and Metabolism-A Concise Review

The consumption of coffee and caffeine (1,3,7-trimethylxanthine) is part of many cultures worldwide. Their properties include serving as a neurostimulant aid, enhancing energy substrate levels, and improving general exercise performance. Both present therapeutic effects that can also be used to control chronic and metabolic diseases due to four mechanisms: adenosine receptor antagonism, increased catecholamine concentrations, a phosphodiesterase inhibitor, and a stimulator of calcium-release channels. Despite the individual genetic variabilities, distinct mechanisms have been demonstrated to improve physical performance, thermogenesis, lipolysis, insulin sensitivity, and hormonal modulation. Thus, coffee consumption and caffeine supplementation may enhance physical and mental performance and may improve metabolic variables, reducing oxidative stress, inflammation, and insulin resistance. Current data reveal vital aspects of coffee and caffeine consumption in specific populations, although further studies are needed to define clinical interventions with caffeine in obesity and chronic conditions.

International society of sports nutrition position stand: coffee and sports performance

Based on review and critical analysis of the literature regarding the contents and physiological effects of coffee related to physical and cognitive performance conducted by experts in the field and selected members of the International Society of Sports Nutrition (ISSN), the following conclusions represent the official Position of the Society:(1) Coffee is a complex matrix of hundreds of compounds. These are consumed with broad variability based upon serving size, bean type (e.g. common Arabica vs. Robusta), and brew method (water temperature, roasting method, grind size, time, and equipment).(2) Coffee's constituents, including but not limited to caffeine, have neuromuscular, antioxidant, endocrine, cognitive, and metabolic (e.g. glucose disposal and vasodilation) effects that impact exercise performance and recovery.(3) Coffee's physiologic effects are influenced by dose, timing, habituation to a small degree (to coffee or caffeine), nutrigenetics, and potentially by gut microbiota differences, sex, and training status.(4) Coffee and/or its components improve performance across a temporal range of activities from reaction time, through brief power exercises, and into the aerobic time frame in most but not all studies. These broad and varied effects have been demonstrated in men (mostly) and in women, with effects that can differ from caffeine ingestion, per se. More research is needed.(5) Optimal dosing and timing are approximately two to four cups (approximately 473-946 ml or 16-32 oz.) of typical hot-brewed or reconstituted instant coffee (depending on individual sensitivity and body size), providing a caffeine equivalent of 3-6 mg/kg (among other components such as chlorogenic acids at approximately 100-400 mg per cup) 60 min prior to exercise.(6) Coffee has a history of controversy regarding side effects but is generally considered safe and beneficial for healthy, exercising individuals in the dose range above.(7) Coffee can serve as a vehicle for other dietary supplements, and it can interact with nutrients in other foods.(8) A dearth of literature exists examining coffee-specific ergogenic and recovery effects, as well as variability in the operational definition of "coffee," making conclusions more challenging than when examining caffeine in its many other forms of delivery (capsules, energy drinks, "pre-workout" powders, gum, etc.).

Overview of Caffeine Effects on Human Health and Emerging Delivery Strategies

Caffeine is a naturally occurring alkaloid found in various plants. It acts as a stimulant, antioxidant, anti-inflammatory, and even an aid in pain management, and is found in several over-the-counter medications. This naturally derived bioactive compound is the best-known ingredient in coffee and other beverages, such as tea, soft drinks, and energy drinks, and is widely consumed worldwide. Therefore, it is extremely important to research the effects of this substance on the human body. With this in mind, caffeine and its derivatives have been extensively studied to evaluate its ability to prevent diseases and exert anti-aging and neuroprotective effects. This review is intended to provide an overview of caffeine's effects on cancer and cardiovascular, immunological, inflammatory, and neurological diseases, among others. The heavily researched area of caffeine in sports will also be discussed. Finally, recent advances in the development of novel nanocarrier-based formulations, to enhance the bioavailability of caffeine and its beneficial effects will be discussed.

High Doses of Caffeine Increase Muscle Strength and Calcium Release in the Plasma of Recreationally Trained Men

The effects of acute caffeine supplementation on muscular strength remain unclear. We examined the effects of two different doses of caffeine on muscle strength and calcium in plasma compared to placebo using a crossover, randomized, double-blind, placebo-controlled design. Twenty-one (n = 21) recreationally resistance-trained participants were randomly assigned into three experimental conditions: 6 mg·kg bw−1 of caffeine (CF6); 8 mg·kg bw−1 of caffeine (CF8); or placebo (PLA), with a 7-day washout period between conditions. Muscular strength assessments were made for both upper (bench press) and lower body muscles (squat and deadlift). Calcium release in plasma was measured on five different occasions. Bench press (CF8: 100.1 ± 1.9 kg; PLA: 94.2 ± 2.5 kg), deadlift (CF8: 132.8 ± 3.5 kg; PLA: 120.7 ± 5.7 kg), and squat (CF8: 130.1 ± 4.9 kg; PLA 119.4 ± 5.4 kg) strength were all significantly (p < 0.001) improved in CF8 compared to PLA. Calcium release in plasma was significantly increased in CF8, whereas no changes were observed in CF6 or PLA. Overall, 8 mg·kg bw−1 of caffeine appears to be an effective dose to optimize upper and lower body muscular strength and calcium release in recreationally trained participants.

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

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

Can I Have My Coffee and Drink It? A Systematic Review and Meta-analysis to Determine Whether Habitual Caffeine Consumption Affects the Ergogenic Effect of Caffeine

OBJECTIVE

The aim was to quantify the proportion of the literature on caffeine supplementation that reports habitual caffeine consumption, and determine the influence of habitual consumption on the acute exercise response to caffeine supplementation, using a systematic review and meta-analytic approach.

METHODS

Three databases were searched, and articles screened according to inclusion/exclusion criteria. Three-level meta-analyses and meta-regression models were used to investigate the influence of habitual caffeine consumption on caffeine's overall ergogenic effect and within different exercise types (endurance, power, strength), in men and women, and in trained and untrained individuals. Sub-analyses were performed according to the following: acute relative dose (< 3, 3-6, > 6 mg/kg body mass [BM]); whether the acute caffeine dose provided was lower or higher than the mean daily caffeine dose; and the caffeine withdrawal period prior to the intervention (< 24, 24-48, > 48 h).

RESULTS

Sixty caffeine studies included sufficient information on habitual consumption to be included in the meta-analysis. A positive overall effect of caffeine was shown in comparison to placebo (standard mean difference [SMD] = 0.25, 95% confidence interval [CI] 0.20-0.30; p < 0.001) with no influence of relative habitual caffeine consumption (p = 0.59). Subgroup analyses showed a significant ergogenic effect when the caffeine dose was < 3 mg/kg BM (SMD = 0.26, 95% CI 0.12-0.40; p = 0.003) and 3-6 mg/kg BM (SMD = 0.26, 95% CI 0.21-0.32; p < 0.0001), but not > 6 mg/kg BM (SMD = 0.11, 95% CI - 0.07 to 0.30; p = 0.23); when the dose was both higher (SMD = 0.26, 95% CI 0.20-0.31; p < 0.001) and lower (SMD = 0.21, 95% CI 0.06-0.36; p = 0.006) than the habitual caffeine dose; and when withdrawal was < 24 h, 24-48 h, and > 48 h. Caffeine was effective for endurance, power, and strength exercise, with no influence (all p ≥ 0.23) of relative habitual caffeine consumption within exercise types. Habitual caffeine consumption did not modify the ergogenic effect of caffeine in male, female, trained or untrained individuals.

CONCLUSION

Habitual caffeine consumption does not appear to influence the acute ergogenic effect of caffeine.

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 ± 7.1 years; height: 179.7 ± 5.6 cm; body mass: 72.15 ± 6.8 kg) participated in a randomized, double-blind, placebo (PLA) controlled crossover design. Participants supplemented with CAF (6 mg/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 ± 92 watts vs. PLA: 659 ± 144 watts; 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 6 mg/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.

Is Coffee a Useful Source of Caffeine Preexercise?

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.

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

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

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 focused 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 randomized 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.

Caffeine and Exercise Performance: Possible Directions for Definitive Findings

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

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

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

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

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

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

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

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

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.

Caffeine and Exercise: What Next?

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.

The Influence of Caffeine Supplementation on Resistance Exercise: A Review

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.

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

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; ηP2 = 0.75) and, overall, resulted in improved 5 km time trial performance (p < 0.001; ηP2 = 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.

MUSCLE STRENGTH AND CAFFEINE SUPPLEMENTATION: ARE WE DOING MORE OF THE SAME?

ABSTRACT The purpose of this review was to examine in the current literature the advances made in terms of the effects of caffeine supplementation on maximum strength and its associated mechanisms since the publication of two important papers in 2010. Searches were carried out in the PubMed, Medline, Scielo and Web of Science databases for articles published after 2010. Sixteen studies were included based on inclusion and exclusion criteria. Five studies did not report changes in maximal voluntary strength (31.3%). Four of them used isometric muscle contractions, although this may not be a key factor because five other studies also used isometric contractions and reported ergogenic effects. Furthermore, these four studies evaluated small muscle groups and volunteers were not accustomed to consuming caffeine. Caffeine produced ergogenic effects in eleven of the sixteen studies analyzed (68.8%). None of the doses were clearly related to ergogenic effects; however, a dose of at least 3 mg/kg of caffeine is probably necessary. Caffeine ergogenicity was affected by various factors. There was a lack of standardized protocols and controls for intervening factors (e.g., circadian cycles and nutritional states), which could affect results. An ideal caffeine supplementation protocol that is useful for future research, athletes, and physical activity practitioners, has yet to be defined. A small advance made since 2010 involved a possible lack of gender difference; it would appear that caffeine supplementation affects men and women equally. Level of Evidence I; Systematic Review of Level I Studies.

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

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 Assessing the Methodological Quality of Systematic Reviews 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 Grading of Recommendations Assessment, Development and Evaluation 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.

Caffeine Supplementation and Physical Performance, Muscle Damage and Perception of Fatigue in Soccer Players: A Systematic Review

Soccer is a complex team sport and success in this discipline depends on different factors such as physical fitness, player technique and team tactics, among others. In the last few years, several studies have described the impact of caffeine intake on soccer physical performance, but the results of these investigations have not been properly reviewed and summarized. The main objective of this review was to evaluate critically the effectiveness of a moderate dose of caffeine on soccer physical performance. A structured search was carried out following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines in the Medline/PubMed and Web of Science databases from January 2007 to November 2018. The search included studies with a cross-over and randomized experimental design in which the intake of caffeine (either from caffeinated drinks or pills) was compared to an identical placebo situation. There were no filters applied to the soccer players’ level, gender or age. This review included 17 articles that investigated the effects of caffeine on soccer-specific abilities (n = 12) or on muscle damage (n = 5). The review concluded that 5 investigations (100% of the number of investigations on this topic) had found ergogenic effects of caffeine on jump performance, 4 (100%) on repeated sprint ability and 2 (100%) on running distance during a simulated soccer game. However, only 1 investigation (25%) found as an effect of caffeine to increase serum markers of muscle damage, while no investigation reported an effect of caffeine to reduce perceived fatigue after soccer practice. In conclusion, a single and moderate dose of caffeine, ingested 5–60 min before a soccer practice, might produce valuable improvements in certain abilities related to enhanced soccer physical performance. However, caffeine does not seem to cause increased markers of muscle damage or changes in perceived exertion during soccer practice.

Supplements with purported effects on muscle mass and strength

PURPOSE

Several supplements are purported to promote muscle hypertrophy and strength gains in healthy subjects, or to prevent muscle wasting in atrophying situations (e.g., ageing or disuse periods). However, their effectiveness remains unclear.

METHODS

This review summarizes the available evidence on the beneficial impacts of several popular supplements on muscle mass or strength.

RESULTS

Among the supplements tested, nitrate and caffeine returned sufficient evidence supporting their acute beneficial effects on muscle strength, whereas the long-term consumption of creatine, protein and polyunsaturated fatty acids seems to consistently increase or preserve muscle mass and strength (evidence level A). On the other hand, mixed or unclear evidence was found for several popular supplements including branched-chain amino acids, adenosine triphosphate, citrulline, β-Hydroxy-β-methylbutyrate, minerals, most vitamins, phosphatidic acid or arginine (evidence level B), weak or scarce evidence was found for conjugated linoleic acid, glutamine, resveratrol, tribulus terrestris or ursolic acid (evidence level C), and no evidence was found for other supplements such as ornithine or α-ketoglutarate (evidence D). Of note, although most supplements appear to be safe when consumed at typical doses, some adverse events have been reported for some of them (e.g., caffeine, vitamins, α-ketoglutarate, tribulus terrestris, arginine) after large intakes, and there is insufficient evidence to determine the safety of many frequently used supplements (e.g., ornithine, conjugated linoleic acid, ursolic acid).

CONCLUSION

 In summary, despite their popularity, there is little evidence supporting the use of most supplements, and some of them have been even proven ineffective or potentially associated with adverse effects.

Effects of different dosages of caffeine administration on wrestling performance during a simulated tournament

The aim of the present study was to investigate the effects of different forms of caffeine administration on physical performance during a simulated wrestling tournament. In a double-blind and randomized experiment, twelve male freestyle wrestlers competed in a simulated wrestling tournament (5 wrestling matches consisting of 2 × 3-min wrestling rounds) following the ingestion of: a placebo, a high-dose of caffeine (10 mg/kg), a moderate-dose caffeine (4 mg/kg), a repeated-dose caffeine (2 mg/kg before each match to a total of 10 mg/kg) or a selective caffeine administration based on performance decrement previously measured (6.16 ± 1.58 mg/kg). The Pittsburgh Wrestling Performance Test (PWPT) was measured before each match to assess physical performance. In comparison to the placebo, the high dose of caffeine only reduced PWPT time before the first match (56.8 ± 2.0 vs. 52.9 ± 1.8 s; p < .05). The moderate dose of caffeine did not affect PWPT performance during the tournament. Both, the repeated dose and the selective administration of caffeine reduced PWPT time with respect to the placebo in the third (66.7 ± 1.8 vs. 63.1 ± 1.4 s; p < .05) and fourth matches (72.3 ± 2.4 vs. 65.9 ± 1.3 s; p < .05). However, only the selective dose of caffeine reduced PWPT time before the fifth match (62.7 ± 3.0 vs. 56.3 ± 2.0; p < .05). The dosage and administration of caffeine affect the ergogenic effects obtained following the ingestion of this substance. An individualized protocol to provide caffeine when physical performance is expected to be reduced might improve wrestling performance during the latter stages of a tournament.

ISSN exercise & sports nutrition review update: research & recommendations

Background

Sports nutrition is a constantly evolving field with hundreds of research papers published annually. In the year 2017 alone, 2082 articles were published under the key words ‘sport nutrition’. Consequently, staying current with the relevant literature is often difficult.

Methods

This paper is an ongoing update of the sports nutrition review article originally published as the lead paper to launch the Journal of the International Society of Sports Nutrition in 2004 and updated in 2010. It presents a well-referenced overview of the current state of the science related to optimization of training and performance enhancement through exercise training and nutrition. Notably, due to the accelerated pace and size at which the literature base in this research area grows, the topics discussed will focus on muscle hypertrophy and performance enhancement. As such, this paper provides an overview of: 1.) How ergogenic aids and dietary supplements are defined in terms of governmental regulation and oversight; 2.) How dietary supplements are legally regulated in the United States; 3.) How to evaluate the scientific merit of nutritional supplements; 4.) General nutritional strategies to optimize performance and enhance recovery; and, 5.) An overview of our current understanding of nutritional approaches to augment skeletal muscle hypertrophy and the potential ergogenic value of various dietary and supplemental approaches.

Conclusions

This updated review is to provide ISSN members and individuals interested in sports nutrition with information that can be implemented in educational, research or practical settings and serve as a foundational basis for determining the efficacy and safety of many common sport nutrition products and their ingredients.

Coffee Ingestion Enhances 1-Mile Running Race Performance

Context: Caffeine, often in the form of coffee, is frequently used as a supplement by athletes in an attempt to facilitate improved performance during exercise. Purpose: To investigate the effectiveness of coffee ingestion as an ergogenic aid prior to a 1-mile (1609 m) race. Methods: In a double-blind, randomized, cross-over, and placebo-controlled design, 13 trained male runners completed a 1-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] min:s.ms) compared with DEC (04:39.14 [00:11.21] min:s.ms; P = .018; 95% confidence interval [CI], −0.11 to −0.01; d = 0.32) and 1.9% faster compared with PLA (04:41.00 [00:09.57] min:s.ms; P = .006; 95% CI, −0.15 to −0.03; d = 0.51). A large trial and time interaction for salivary caffeine concentration was observed (P < .001; ), 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 = .602; 95% CI, −0.09 to 0.03; d = 0.17). Furthermore, only trivial differences were observed for blood glucose (P = .839; ) and lactate (P = .096; ) and maximal heart rate (P = .286; ) between trials. Conclusions: The results of this study show that 60 minutes after ingesting 0.09 g·kg−1 of caffeinated coffee, 1-mile race performance was enhanced by 1.9% and 1.3% compared with placebo and decaffeinated coffee, respectively, in trained male runners.

Acute Ingestion of Caffeinated Chewing Gum Improves Repeated Sprint Performance of Team Sport Athletes With Low Habitual Caffeine Consumption

The effects of acute ingestion of caffeine on short-duration high-intensity performance are equivocal, while studies of novel modes of delivery and the efficacy of low doses of caffeine are warranted. The aims of the present study were to investigate the effect of acute ingestion of caffeinated chewing gum on repeated sprint performance (RSP) in team sport athletes, and whether habitual caffeine consumption alters the ergogenic effect, if any, on RSP. A total of 18 male team sport athletes undertook four RSP trials using a 40-m maximum shuttle run test, which incorporates 10 × 40-m sprints with 30 s between the start of each sprint. Each participant completed two familiarization sessions, followed by caffeine (CAF; caffeinated chewing gum; 200 mg caffeine) and placebo (PLA; noncaffeinated chewing gum) trials in a randomized, double-blind manner. RSP, assessed by sprint performance decrement (%), did not differ (p = .209; effect size = 0.16; N = 18) between CAF (5.00 ± 2.84%) and PLA (5.43 ± 2.68%). Secondary analysis revealed that low habitual caffeine consumers (<40 mg/day, n = 10) experienced an attenuation of sprint performance decrement during CAF relative to PLA (5.53 ± 3.12% vs. 6.53 ± 2.91%, respectively; p = .049; effect size =0.33); an effect not observed in moderate/high habitual caffeine consumers (>130 mg/day, n = 6; 3.98 ± 2.57% vs. 3.80 ± 1.79%, respectively; p = .684; effect size = 0.08). The data suggest that a low dose of caffeine in the form of caffeinated chewing gum attenuates the sprint performance decrement during RSP by team sport athletes with low, but not moderate-to-high, habitual consumption of caffeine.

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

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.

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

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; ηP2 = 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; ηP2 = 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; ηP2 = 0.01). Neither the ingestion of COF or CAF improved repeated sprint cycling performance in relatively untrained males.