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Caffeine, Energy Drinks, and Strength-Power Performance
Abstract
CAFFEINE AND ENERGY DRINKS ARE POPULAR SUPPLEMENTS THAT HAVE VARIABLE USES IN BOTH ATHLETIC AND NONATHLETIC POPULATIONS. EVIDENCE HAS BEEN RELATIVELY CONSISTENT IN SHOWING THE EFFICACY OF THESE “HIGH-ENERGY” COMPOUNDS IN ENHANCING ENDURANCE PERFORMANCE, BUT LESS IS UNDERSTOOD REGARDING ITS ERGOGENIC POTENTIAL IN STRENGTH/POWER ACTIVITIES. THIS REVIEW FOCUSES ON THE EFFICACY ON THESE PRODUCTS (CAFFEINE BY ITSELF OR IN COMBINATION WITH OTHER INGREDIENTS) ON STRENGTH/POWER PERFORMANCE AND REACTION TIME. IN ADDITION, DISCUSSION ON THE EFFICACY OF CAFFEINE DURING PROLONGED ACTIVITY AND ITS ROLE DURING TACTICAL PERFORMANCE IS ADDRESSED.
... One study found that ingestion of caffeinated EDs increased maximal voluntary isometric contraction strength in young, healthy males [11]. Another study identified that caffeine and ED intake improved sprinting performance and improved reaction time and agility in young, healthy males [12]. While some studies have shown a link between caffeine and increased repetition and power output during exercise [12], others have identified no change in these outcomes between EDs and placebo [13]. ...
... Another study identified that caffeine and ED intake improved sprinting performance and improved reaction time and agility in young, healthy males [12]. While some studies have shown a link between caffeine and increased repetition and power output during exercise [12], others have identified no change in these outcomes between EDs and placebo [13]. For instance, in a 2015 study, Trevino et al. [17] observed no distinction in biceps muscle activation after energy drink ingestion. ...
... Caffeine, by itself can stimulate the central nervous system [15]. As mentioned, EDs often contain other ingredients such as taurine, guarana, and riboflavin, among others, which can alter the central nervous system in harmful matter [16, &17] Merely a few studies have approached the connection between energy drinks and caffeine with the central nervous system (CNS) [3,5,9,11,12,15,18]. Diminished blood flow [19] to peripheral structures, including muscles and nerves of the extremities, could potentially increase fatigue, thus altering the standing balance. ...
Background: In recent years, energy drink consumption (EDC) has flared up among college students in the 18-34-year-old male demographic. Energy drinks cause balance alterations, reduction of blood flow, and distort lower limb neuromuscular activation. Purpose/Objective: We strived to discover which specific additive among three different drinks (Red Bull, Rockstar, Bang) could contribute to abnormalities in stability, memory, and muscle activation. Therefore, this investigation’s aim is two-fold. First, we assessed the impact of EDC on muscle activation/fatigue and standing balance during multitasking activities. Second, we propose to determine the effect of EDC on memory during multitasking activities. Methods: Twenty healthy young adults ranging from 22 to 28 years old, took part in the study. Demographic and cardiovascular data were collected, and later all participants completed cognitive evaluations (memory, motor speed) before the EDC. We obtained neuromuscular data via EMG sensors placed on hand grip muscles (wrist flexors) before performing the balance (no foam/foam, EO/EC) and motor (while holding a water cup; no nodding/nodding) tasks measured by accelerometers. Each participant completed all tasks pre- and post-16-ounce EDC. A MANOVA analysis was implemented to compare pre- and post-data. Statistical significance was set at p<0.05.Results: Among the three diverse drinks, 1) A trend to reduce jerk movements (postural sway) was detected mostly in the anterior-posterior (AP) direction with the Red Bull group and 2) Handgrip neuromuscular data revealed an adaptation in diverse timing variables, more noticeable with the Red Bull group during muscle timing decay. 3) Finally, the memory protocol yielded no results after EDC. Conclusions: While this study's outcomes did not show a substantial distinction between pre and post-EDC for the variables measured, among the three drinks, Red bull exhibited alterations. The reduction in EMG activity decay in the Red Bull group may suggest an early onset of muscle fatigue following EDC. Nevertheless, it seems that the reduced sway compensates for this early decay during the balance tests. Clinical relevance: This study pointed out that some of the ingredients in Red Bull alter muscle activation and balance. Further research is warranted to gain a better understanding of the effects of Red Bull’s ingredients on muscle fatigue and balance.
... Over the last decade, energy drinks have grown in popularity among youth, with reported consumption prevalence varying from a daily prevalence of 5% to biweekly prevalence of 42% among youth (2). Recent evidence suggests that energy drinks are available in more than 140 countries (3). The Unit-ed States energy drink industry is anticipated to reach nearly 20$ billion by 2013, an increase of almost 160% since 2008 and it is estimated that 24-56% of the adolescent to middle aged population are energy drink consumers (4). ...
... Marketing strategies are aimed at young, athletic populations. Supplement companies are frequently serving as event sponsors, and their products are endorsed by competitive athletes (3). Also, they state that these productsmay boost energy, concentration, and athletic performance (2). ...
... Also, they state that these productsmay boost energy, concentration, and athletic performance (2). The success of these strategies is evidenced by reports indicating that half of the energy drinks are sold to individuals of 25 years and younger (3). ...
There is little information about the effect of energy drink on elite adolescent female swimmers. The aim of this study was to investigate the effectiveness of energy drink to improve physical performance and some physiological factors in female swimmer players. 36 elite adolescent female swimmers (all participants in the national competition authority had earned or were invited to national team; 13.73±1 years, weight 45.67±3.70, height 149.5±7.30 cm and body mass of 20.39±1.5 kg/m2) Volunteered to participate in this study. A double-blind, placebo controlled and randomized experimental design was used in this investigation. In two sessions with an interval of 4 days of each other, 36 female swimmers ingested 6 mg/kg Big Bear energy drink or placebo. 15 min after consumption, they performed of tests as below: one repetition maximum and 60% of one repetition maximum in the chest press and leg press, explosive power test, anaerobic RAST test, 100 m swim Crawl at maximal speed, aerobic Queens College Step test. Also before, immediately after RAST test, 5 cc of blood from brachial vein to measure blood lactate was taken from subjects, and the results were recorded. Also, participants rating of perceived exertion (RPE) scale (Borg 15 rank) filled out before and after the muscular endurance test. In comparison to the placebo drink, the ingestion of drink reduces the 100m crawl record (97.12±4.68 s vs 94.73±4.37 s, respectively; P=0.02). The ingestion of the energy drink did not affect other performance indicators. Also, blood lactate levels and RPE during the post exercise was unaffected by the energy drink ingestion. A energy drink with a dose equivalent to 6 mg/kg ineffective on performance indicators (muscle strength, muscular endurance, explosive power, aerobic power, anaerobic power), blood lactate levels and rating of perceived exertion in elite adolescent female swimmers.
... Sporcularda kafeinin besin takviyesi olarak alımı sıklıkla görülmektedir. Dünya Anti-Doping Ajansı, 2004 yılında kafeini yasaklı maddeler listesinden çıkartmasıyla birlikte, elit düzeyde kullanımı daha yaygın hale gelmiştir (McCormack & Hoffman, 2012). Kafein hızla bağırsak seviyelerinde emilir (Fredholm, 1995), alımından 15-45 dakika sonra kanda yüksek konsantrasyon seviyelerine ulaşır ve bir saat sonra da maksimum seviyelerine erişir (Harland, 2000). ...
... Kısa süreli, yüksek yoğunluklu yüklenmeler esnasında ise artan güç çıktısı, anaerobik güç kapsamındaki kafein alımına atfedilen temel ergojenik fayda olarak öne sürülmüştür. Kafeinin merkezi sinir sistemi üzerindeki en belirgin etkilerinden biri, adenozin reseptörlerine bağlanarak ve adenozinin vücut üzerindeki inhibitör etkilerini azaltarak yorgunluğu ertelemeye yardımcı olabilecek bir adenozin antagonisti olarak hareket etmesidir (McCormack & Hoffman, 2012;Allman vd., 2015). ...
... Several studies have reported the ergogenic effects of acute CAF intake, mainly in endurance performance tasks [3][4][5] . However, the results are contradictory for high-intensity exercises, especially in strength exercises 5,6 . ...
... CAF as an ergogenic resource has been a source of many studies; there is still no consensus on the effects on anaerobic performance 6,7,33,35 . Although different physiological mechanisms of CAF, the predominant mechanism for each bioenergetics pathway is not well described. ...
... The most popular pre-workout supplement is caffeine (CAF) which enhances performance through peripheral and central mechanisms [6,7,8,9]. The effects of CAF ingestion on aerobic performance are well documented [10], and previous studies also have focused on the impact of CAF consumption on anaerobic performance [11,12]. However, the effects of CAF on muscle strength, power, speed, and agility are inconsistent [12]. ...
... The effects of CAF ingestion on aerobic performance are well documented [10], and previous studies also have focused on the impact of CAF consumption on anaerobic performance [11,12]. However, the effects of CAF on muscle strength, power, speed, and agility are inconsistent [12]. Previous studies reported a slight improvement in reactive agility [13] or no effect [10] of CAF at the same dose of 6 mg/kg. ...
Background: The purpose of this study was to examine the acute effect of a caffeine-based multi-ingredient supplement (MS) on the reactive agility and jump performance in recreational handball male players.
Methods: A randomized, double-blind, crossover study involved twenty-four male handball players. All participants were tested under three conditions: placebo, caffeine, or MS ingestion 45 minutes before exercise tests. Participants performed a reactive agility test (Y-test: 1-1-2 test) and countermovement jump (CMJ).
Results: None of the supplements improved countermovement jump height. The time needed to complete the 1-1-2 test was significantly shorter in MS condition compared to placebo. The differences in agility between PL vs. caffeine and MS vs. caffeine conditions were not statistically significant.
Conclusions: The results of this study indicate that the caffeine-based multi-ingredient performance was effective in improvement in reactive agility but not in jump height in recreational handball male players. A similar effect was not observed with caffeine ingestion alone. Further comparative studies (MS ingestion vs. only caffeine ingestion) and MS with different compositions are needed.
... The most popular pre-workout supplement is caffeine (CAF), which enhances performance through peripheral and central mechanisms [6][7][8][9]. The effects of CAF ingestion on aerobic performance are well documented [10], and previous studies also focused on the impact of CAF consumption on anaerobic performance [11,12]. However, the effects of CAF on muscle strength, power, speed, and agility are inconsistent [12]. ...
... The effects of CAF ingestion on aerobic performance are well documented [10], and previous studies also focused on the impact of CAF consumption on anaerobic performance [11,12]. However, the effects of CAF on muscle strength, power, speed, and agility are inconsistent [12]. Previous studies reported a slight improvement in reactive agility [13] or no effect [10] of CAF at the same dose of 6 mg/kg. ...
Pre-exercise caffeine and guarana-based multi-ingredient supplement (MS) consumption
may be more effective for physical performance improvement than caffeine and guarana alone due to the synergistic effect of biologically active ingredients in multi-ingredient supplements. This study aimed to examine the acute effect of MS on the reactive agility and jump performance in recreational handball male players. A randomized, double-blind, crossover study involved twenty four male handball players (body mass 74.6 � 8.8 kg; body height 179 � 7 cm; age 23.8 � 1.4 years).Participants were tested under three conditions: placebo, caffeine + guarana (CAF + GUA), or MS ingestion 45 min before exercise tests. Participants performed a reactive agility test (Y-shaped test) and countermovement jump (CMJ). None of the supplements improved countermovement jump height (p = 0.06). The time needed to complete the agility test was significantly (p = 0.02) shorter in the MS condition than in the placebo. The differences in agility between PL vs. CAF + GUA and MS vs. CAF + GUA conditions were not statistically significant (p = 0.88 and p = 0.07, respectively). The results of this study indicate that the caffeine-based multi-ingredient performance was effective in improvement in reactive agility but not in jump height in recreational handball male players. A similar effect was not observed with CAF + GUA ingestion alone.
... coffee, energy drinks, 'pre-workout' sports supplements) prior to the biomechanical and physical performance assessments. This was to ensure performance was not influenced by nutritional aids given the role of caffeine in enhancing measures of muscular strength (Astorino & Roberson, 2010;Duncan, Stanley, Parkhouse, Cook, & Smith, 2013), power (McCormack & Hoffman, 2012) and sprint performance (Trexler, Smith-Ryan, Roelofs, Hirsch, & Mock, 2016). In addition, boxers were also required to abstain from consuming other sports supplements such as creatine, betaine, β-alanine, β-hydroxy β-methylbutyrate (HMB) etc. given the muscular strength, power and hypertrophy increases associated with such supplements (Ismaeel, 2017;Lanhers et al., 2015;Maté-Muñoz et al., 2018;McIntosh, Love, Haszard, Osborne, & Black, 2018;Nunes et al., 2017). ...
Punches in boxing are intricate actions requiring the coordinated and synergistic recruitment of leg, trunk and arm musculature. Maximal punches can have a marked impact on the outcomes of boxing contests. Currently, there is an absence of research appraising the biomechanics and physical performance-related qualities associated with boxing punches, and as such, there are no practical guidelines pertaining to resistance training and its impact upon these important characteristics. In this respect, coaches and boxers are reliant consequently upon non-scientific approaches to training and contest preparation. Thus, the purpose of this thesis was to quantify the biomechanics and physical performance-related qualities associated with maximal punching techniques common to amateur boxing, and investigate the extent to which resistance training enhances such features.
Study 1 quantified the three-dimensional kinetics and kinematics of maximal punches common to boxing competition to identify the differences between punch types (straights, hooks, and uppercuts), whilst Study 2 investigated the movement variability of these measures across punch types. These studies revealed significant differences for the majority of kinetic and kinematic variables between punch types. High within-subject, between-subject, and biological variability were recorded for the same variables across punch types, independent of the amount of boxing experience. These findings confirm that kinetic and kinematic characteristics vary from punch to punch, with boxers appearing to manipulate kinematic variables in order to achieve a consistent intensity and end-product. Study 3 quantified the relationships between physical performance-related traits and kinetic and kinematic qualities of maximal punches, and revealed moderate-to-large associations with muscular strength and power. From this, Study 4 appraised the extent to which strength and contrast resistance training enhanced maximal punch biomechanics and physical performance-related qualities. The findings highlighted that contrast training was superior among male amateur boxers over a six-week intervention, though strength training alone also brought about improvements.
This current research has advanced our understanding of maximal punching and the influence of resistance training on a variety of its determinants. Nonetheless, future research is required to identify if the same findings can be generalised to higher standards of boxing and whether alternative strength and conditioning strategies are equally, or more effective.
... Co ee is an example of a beverage with high levels of ca eine (antioxidants), and it is four times that of tea (Escott-Stump, 2008) . In addition, ca eine acts as a central nervous system stimulant with a similar e ect to amphetamine, though weaker (McCormack and Ho man, 2012) . ...
The cooling-heating method was used to successfully synthesize molecularly imprinted polymers on caffeine. Caffeine was used as a template and mixed with chloroform solvent, methacrylic acid as a monomer, ethylene glycol dimethacrylate as a cross-linker, and benzoyl peroxide as an initiator. The solution was stirred for 15 minutes and placed in a vial. Then it was placed in a cooler with a temperature of -5○C for 60 minutes and then inserted into an oven with an increasing temperature at 75○C, 80○C, and 85○C for 3, 2 and 1 hour, respectively. Furthermore, the repeated washing process resulted in solid polymer, which was subjected to template leaching to produce polymers with specific cavities called molecularly imprinted polymers (MIP). The resulting caffeine polymer and MIP were tested using SEM, FTIR, and XRD methods. In addition, the SEM image analysis data showed 388 cavities in the polymer after template leaching, compared to the 121 cavities in the unwashed polymer. This result was supported by the FTIR spectrum analysis which showed that caffeine MIP has a higher transmittance value than the polymer. Therefore, the caffeine concentration was significantly reduced after the leaching process. The XRD spectra showed that caffeine MIP had a smaller halfmaximum diffraction peak width (FWHM) compared to the polymer. Also, the low FWHM value depicted a larger crystalline size in the caffeine MIP compared to the polymer.
... Few studies have examined the connection between Edrinks and caffeine and the central nervous system (CNS) [8][9][10][11][12][13]. Caffeine by itself has the potential to stimulate the central nervous system [12] and leads to an increase in sway in healthy young adults after a 200-milligram pill [14]. ...
Over the past few years, energy drink consumption has increased among students aged 18–34 years. Energy drinks alter the balance, reduce blood flow and interfere with neuromuscular activation in the lower extremities. We attempted to determine which specific additive of three different drinks (red bull, rockstar, and bang) could contribute to changes in muscle activation of the ankle complex. Twenty healthy young adults aged 22–28 years were included in this study and allocated among 3 groups, red bull, rockstar, and bang. Neuromuscular data were obtained from EMG sensors positioned on the anterior tibialis and gastrocnemius before completing the four balance tasks. Each participant completed all the tasks before and after the 16-ounce Edrink. ANOVA was performed to compare the data before and after the beverage. Statistical significance was set at P <0.05. A trend was observed in red bull and bang groups revealing a faster anterior tibial activity and prolong activation for gastrocnemius. The rockstar group also showed a more rapid activation trend and shorter response during all tasks for the gastrocnemius. It appears that the additives found in Redbull and Bang produce an increased posterior sway, indicated by the faster activity observed on the anterior tibial muscle. On the other hand, the elements encountered in rockstars provoke anterior movements, creating the need for a quicker response from the gastrocnemius muscle. Further research is required to explore certain energy drink ingredients' effects on dynamic activities such as walking.
... Fuente: Elaboración propia. 10,11,12,13,14,15,16,17,18,19,20,21,22,23 En los últimos años, se ha generado literatura creciente respecto a los eventos adversos a la salud ocasionados por la ingestión de las bebidas energéticas. En una revisión sistemática realizada por Ali y colaboradores, se reportó que el consumo de estas bebidas es mayor en adolescentes y en adultos jóvenes de sexo masculino. ...
Resumen Introducción: Las bebidas energéticas son productos que están compuestos por diversas sustancias que podrían causar efectos nocivos para la salud. El consumo de estas bebidas ha aumentado en los últimos años en jóvenes que buscan efectos que ayuden en su mejoramiento y rendimiento, ya sea académico o deportivo. Objetivo: Conocer la frecuencia y las principales razones del consumo de bebidas energéticas, así como determinar los efectos asociados al consumo de bebidas energéticas en estudiantes de la Universidad de la Cañada. Metodología: Se realizó un estudio de enfoque cuantitativo, tipo descriptivo, observacional y transversal, aplicando encuestas, con un nivel de confianza del 95% y una precisión del 5%. Resultados: De un total de 334 alumnos inscritos en las diferentes carreras de la Universidad, se encuestaron a 179 alumnos mediante un muestreo aleatorio simple. El 68.5% de los encuestados mencionan que por lo menos alguna vez en su vida han probado dichas bebidas, mientras que el 31.28% la consumió durante la investigación. El 76.78% consume en promedio de 1 a 3 latas al mes. Siendo las principales razones de consumo: mantenerse despierto, aumentar el rendimiento deportivo y potenciar el efecto del alcohol. Las marcas de mayor preferencia fueron Vive 100 seguida de Red Bull. Para ambas marcas, las palpitaciones y el dolor de cabeza son los principales efectos adversos. Conclusiones: A pesar de que el Abstract Introduction: Energy drinks are products composed of various substances that could cause harmful health effects. The consumption of these drinks has increased in recent years in young people seeking effects that help improve their performance in academics or sports. Objective: To determine the frequency and principal reasons for the consumption of energy drinks, as well as the effects associated with their consumption, in students from the University of Cañada. Methodology: A quantitative, descriptive, observational and cross-sectional study was conducted. Surveys with a confidence level of 95% and a precision of 5% were applied. From the total of 334 students enrolled in different careers at the University, 179 students were surveyed using simple random sampling. Results: 68.5% of respondents mentioned that at least once in their life they have tried energy drinks, while 31.28% consumed it during the investigation. 76.78% reported they consume on average 1 to 3 cans a month. The main reasons cited for consumption were: to stay awake, increase sports performance and enhance the effects of alcohol. The most preferred brands were Vive 100 followed by Red Bull. For both preferred brands, palpitations and headaches are the main adverse effects. Conclusions: Although the consumption of these beverages is low, it is necessary to implement a dissemination program to raise awareness among students about the adverse effects associated with the
... Bebidas energéticas (BE) são produtos que contêm cafeína e, nos últimos anos, têm sido utilizados como recurso ergogênico por atletas 1,2 . Um dos principais ingredientes das BE que se relaciona com o desempenho é a cafeína 2 , a qual é absorvida rapidamente e alcança um pico de concentração plasmática máxima entre 30 a 60 min após a ingestão 3,4 . Contudo, além da cafeína, as BE podem conter na sua composição substâncias como taurina, carboidratos, aminoácidos e vitaminas, possibilitando um efeito aditivo ou sinérgico à ação da cafeína 1,2 . ...
RESUMO: The purpose of this study was verify the acute influence of caffeine-containing energy drinks (ED) on resistance exercises performance. Heart rate (HR) was include as additional variable. In a double-blind cross-over randomized design, fifteen healthy and trained subjects (9 males; 6 females: 21.6 ± 0.5 yrs; 171.1 ± 2.3 cm; 66.1 ± 2.6 kg) performed two experimental sessions (48h of minimum interval) in knee extension and chest-press (75% 1RM until fatigue, 3 sets, 90 s of rest interval between sets, 3 min of rest interval between exercises). In one day, the subjects intake ED (2.5 mg of caffeine per body mass kg) or placebo 60 min before the exercises. The beverages were equalized by calories amount. The HR was measured during the rest, 60 min after the beverages intake and at the end of each exercise sets. The results showed that ED intake improved the amount of repetitions in relation to placebo in chest-press (27.3±2.8 vs 23.9±3.0; P=0.03) and knee extension (36.0±2.2 vs 33.8±2.1; P=0.02). The HR was higher after ED intake than placebo (P<0,05) before and after each exercise sets. In conclusion, ED intake improve the resistance exercises performance until exhaustion with increase in HR.
... In these studies, the caffeine dosage ranged from 1.5 mg per kg of body weight to almost 9 mg. The caffeine action may be linked to alterations in the central nervous system (14,30), an increase in the activity of caffeine on adenosine receptors (21), caffeine consumption by athletes and physically active people with a view to improving performance (17,25,29). One of the reasons for the increase in ED consumption is that, to increase the effects of caffeine, most of these beverages contain various additional ingredients to provide a synergistic or additive effect (2), such as guarana extract, taurine, amino acids, carbohydrates and vitamins (22,27). ...
Caffeine containing energy drink (ED) is frequently used as ergogenic aid, but its effect on performance need more investigation. Thus, the aim of this study was to analyze the effects of acute ingestion of an ED on the physical performance of resistance-trained men subjected to successive tests in the same experimental protocol. Fifteen resistance-trained males (21.0 ± 0.3 yrs; 177.4 ± 1.8 cm; 79.6 ± 1.8 kg) ingested 2.5 mg caffeine per kg of body weight (619.5 ± 14.6 mL of ED) or a placebo in a double-blind randomized cross-over design. Physical performance was randomized for the maximum repetition tests (80% 1RM) in the bench press exercise and unilateral knee extension (dominant leg), maximal isometric hand-grip test in both hands, standing long jump and repeated sprint ability test. The paired Student-t test showed that ED intake increased performance compared to the placebo for the number of repetitions in the unilateral knee extension test of the dominant leg (11.5 ± 0.9 reps vs 9.5 ± 0.8 reps; P = 0.001) and bench press (10.2 ± 0.4 reps vs 8.1 ± 0.5 reps; P = 0.01); and also increased isometric strength in the hand-grip maximal test in the right (53.7 ± 1.5 kg vs. 47.7 ± 1.6 kg; P = 0.02) and left hand (52.9 ± 1.5 kg vs. 45.9 ± 1.3 kg; P = 0.02). In conclusion, acute ingestion of ED increased performance only in specific strength tests in resistance-trained men.
... Enhanced secretion of β-endorphins has also been documented, allowing for prolonged performance as a result of reduced pain perception [4]. Mechanisms of action in terms of strength performance are still not clear, however, theories for both central and peripheral factors have been postulated [5]. Possible mechanisms may include increased muscle activation, motor unit recruitment [6,7], and enhanced excitation contraction coupling [6]. ...
Acute Effects of Caffeine on Strength Performance in Trained and Untrained Individuals
Objective: The primary aim of this study was to compare the acute effects of a caffeine based supplement on the strength performance of trained and untrained individuals with a secondary investigation into the effects of a placebo. Method: Seven resistance trained (>6 months) and seven untrained (<6 months) males (mean ± SD: age: 21 ± 3 y, mass: 75.2 ± 11.3 kg, height: 176 ± 6 cm) consumed either caffeine (CAF) (5 mg.kg.bw-1), placebo (PLA) or nothing (CON) 60 minutes prior to 1 RM squat measurements in a double-blinded, repeated measures design. A two way repeated measures ANOVA was applied to test for the main effects of condition (CAF, PLA, CON) and group (Trained, Untrained), and the interaction effect (condition x group). Results: A significant interaction effect (F(2,11)=4.38, p=0.024) for 1 RM was observed. In the untrained group there was significant difference between CON and PLA (p<0.001). On average 1 RM in the untrained group was 12% lower in the CON trial (92.1 kg) compared to the PLA (102.9 kg; 95% CI=-5.3 to -16.1 kg), and 9% lower compared to CAF (p=0.005; 95% CI=-2.7 to 14.5 kg). There was no significant difference in 1 RM in the untrained group between PLA and CAF (p=0.87, 95% CI -3.2 to 7.5 kg). Additionally, there were no significant differences for the trained group between conditions. There was also a significant main effect for condition for 1 RM (F(2,11)=12.81, p<0.001) . Overall the CON trial was 6% lower (p=0.001, 95% CI=-3.0 to -10.6 kg) than the PLA trial (117.9 kg; 95% CI 97.6 to 124.6 kg), and 5% lower (p=0.12, 95% CI=-1.2 to -9.5 kg) than the CAF trial (116.4 kg; 95% CI 105.0 to 127.8 kg). There was no significant difference between PLA and CAF (p=0.951). Finally, there was a significant main effect for group (F(1,12)=8.79, p=0.12). On average 1 RM was 25% higher in the trained group (131.7 kg; 95% CI=114.5 to 148.9 kg) compared to the untrained group (98.6 kg; 95% CI=81.4 to 115.8 kg). Conclusion: These findings suggest that both a caffeine supplementation and placebo improve 1 RM in untrained individuals but do not improve performance in resistance trained athletes. No significant differences between caffeine and placebo, suggests placebo induced mechanisms also need to be considered.
... Research has demonstrated that large doses of caffeine have improved aerobic endurance performance in elite athletes, such as cyclists or runners (8,11,13,25,38,54). Despite the known ergogenic effect of caffeine on aerobic performance, the benefit of caffeine supplementation on improving resistance training variables, for example power and power endurance, is less clear (30,36,45). ...
Background: Caffeine is a substance that is consumed regularly by
approximately 90% of adults worldwide, primarily to reduce fatigue and increase wakefulness. The benefit of caffeine consumption on athletic performance in large doses (3-9 mg/kg body weight or BW) is well documented in aerobic athletes. However, the benefits of caffeine consumption on resistance training variables such as power are less clear. Purpose: The purpose of this study was to investigate the effect of consumption of 7 mg/kg BW of caffeine on power production in experienced, resistance trained college-aged males, who are habitual caffeine consumers. Methods: Eighteen young and healthy college aged males (aged 21.7 ± 2.0 yrs) were included in this double blind, placebo controlled study. Subjects performed a battery of tests that included a vertical jump (VJ), isometric squat (ISO), and Smith Machine squat (SQF) and bench press (BPF) to failure at 60% 1RM. Subjects consumed either 7 mg/kg body weight (BW) of caffeine or placebo, 60 minutes prior to testing. Test sessions were separated by 7 days. Power production during VJ, SQF and BPF exercises was evaluated. Power obtained during SQF and BPF was used to find the fatigue index (F.I.). Also, force production during an ISO was assessed. A repeated measures ANOVA was used to determine differences between treatments. Significance for all analysis was set at p≤ 0.05. Results: There were no significant differences between treatments in VJ, ISO, SQF, or BPF. Conclusion: Consumption of 7 mg/kg BW of caffeine does not improve measures of force, power, or fatigue during resistance training exercises in habitual caffeine users.
Atualmente, muitos jovens, influenciados pela mídia, têm utilizado Recursos Ergogênicos (RE) (substâncias utilizadas com o intuito de melhorar o desempenho esportivo). Sem atentar para os malefícios à saúde, o abuso de tais substancias podem acarretar efeitos irreversíveis. Objetivo: analisar a prevalência e traçar um perfil dos usuários de RE em discentes do curso de graduação em Educação Física. Método: trata-se de um estudo transversal descritivo, realizado com 200 discentes de uma Instituição de Ensino Superior (IES) localizada na cidade de Fortaleza – CE. Os estudantes, de ambos os sexos, têm idade superior a 18 anos. Foram incluídos aqueles que praticam algum esporte há, no mínimo, 3 meses, através de um inquérito, com questões abertas e fechadas. Resultados e Considerações finais: concluiu-se que a maioria dos voluntários é do sexo masculino, com idade entre 20 e 35 anos, os produtos mais consumidos são suplementos proteicos, vitamínicos e creatina. A utilização de RE é contínua e a procura por nutricionistas ou médicos é baixa, sendo a orientação sobre o uso de ergogênicos obtida de fontes pouco confiáveis, como amigos e internet. A maioria dos usuários não se mostrou preocupada com eventuais problemas de saúde por seu uso indiscriminado.
The objective of this study was to estimate the possibility of caffeine consumption influence on students, involved in table tennis playing, mental status regulation and their competitive activity improving. Five female (age 19.9 ± 1.7, height 167.6 ± 6.9 cm, weight 65.8 ± 12.1 kg) and four male (age 20.7 ± 1.8, height 177.4 ± 6.4 cm, weight 94.8 ± 16.6 kg) students (experience of playing table tennis 2-4 years) took part in the study. Target precision of backhand drive and ball velocity (used videotaping 240 Hz and video analysis with Kinovea software) and also simple and choice reaction time (used Reaction Time Test software) were determined without and after caffeine consumption (5.3 ± 0.2 mg/kg). It was found that all studied parameters in the examined group were identical under normal conditions and after caffeine consumption (p > 0.05). However, among some subjects, there was a significant improvement in the target precision of backhand drive (p = 0.012) and increasing the ball velocity (p = 0.000), which allows to consider it necessary to study the individual reaction of table tennis players to caffeine consumption.
The objective of this study was to investigate the impact of Burn energy drink on sprint running performance. Eight sprint runners and combine event athletes took part in the investigation: four men (age 20.78 ± 1.27 years, height 184 ± 3 cm, weight 76.5 ± 4.7 kg, 100 meter personal best 11.21 ± 0.55 s) and four women (age 20.77 ± 2.01 years, height 168 ± 9 cm, weight 56.8 ± 5.6 kg, 100 meter personal best 12.93 ± 0.56 s). Each participant performed 50 meter maximal speed running (starting shot) using starting blocks after individual worming up, then consumed 0.33 liter of "Burn® Energy Drink Original" and performed maximal sprint running again after 30 minutes of active rest. Kinovea video analysis was used for evaluating of the athletes times in different parts of 50 meter distance, speed and other characteristics of sprint running. There were used four camcorders (240 Hz) placed 20 meters from running track. Optical axes of cameras were aligned to the 1-m, 20-m, 40-m and 50-m lines perpendicular to the running track. The paired sample t-test was used to determine the differences significance between data before-and-after Burn energy drink consuming. The authors have not found the significant differences in the running times on the 1-m (0.617 ± 0.037 and 0.613 ± 0.053 с, p = 0.7649) and 50-m (7.168 ± 0.417 and 7.221±0.463, p = 0.0649) marks before and after consuming energy drink. Average speed during running step on the 20-m mark did not change (8.17 ± 0.52 and 8.12 ± 0.54 m/s, p = 0.3050) and significantly decreased on the 40-m mark (8.56 ± 0.73 and 8.48 ± 0.77 m/s, p = 0.0498) after consuming energy drink. All other characteristics of sprint running technique were stable. Now then, Burn energy drink does not improve sprint running performance.
The objective of this study was to investigate the impact of Burn energy drink on sprint running performance. Eight sprint runners and combine event athletes took part in the investigation: four men (age 20.78 ± 1.27 years, height 184 ± 3 cm, weight 76.5 ± 4.7 kg, 100 meter personal best 11.21 ± 0.55 s) and four women (age 20.77 ± 2.01 years, height 168 ± 9 cm, weight 56.8 ± 5.6 kg, 100 meter personal best 12.93 ± 0.56 s). Each participant performed 50 meter maximal speed running (starting shot) using starting blocks after individual worming up, then consumed 0.33 liter of "Burn® Energy Drink Original" and performed maximal sprint running again after 30 minutes of active rest. Kinovea video analysis was used for evaluating of the athletes times in different parts of 50 meter distance, speed and other characteristics of sprint running. There were used four camcorders (240 Hz) placed 20 meters from running track. Optical axes of cameras were aligned to the 1-m, 20-m, 40-m and 50-m lines perpendicular to the running track. The paired sample t-test was used to determine the differences significance between data before-and-after Burn energy drink consuming. The authors have not found the significant differences in the running times on the 1-m (0.617 ± 0.037 and 0.613 ± 0.053 с, p = 0.7649) and 50-m (7.168 ± 0.417 and 7.221 ± 0.463, p = 0.0649) marks before and after consuming energy drink. Average speed during running step on the 20-m mark did not change (8.17 ± 0.52 and 8.12 ± 0.54 m/s, p = 0.3050) and significantly decreased on the 40-m mark (8.56 ± 0.73 and 8.48 ± 0.77 m/s, p = 0.0498) after consuming energy drink. All other characteristics of sprint running technique were stable. Now then, Burn energy drink does not improve sprint running performance.
در سالهای گذشته، مصرف نوشابههای انرژیزا در میان ورزشکاران برای افزایش عملکرد در هنگام تمرین و موفقیت در رقابتها افزایش قابل توجهی داشته است. هدف از این پژوهش، بررسی اثر مصرف نوشابه انرژیزای هایپ، قبل از فعالیت بر شاخصهای عملکردی و لاکتات خون بدمینتون بازان زبده بود. بدین منظور، ده نفر از بدمينتونبازان زبده پسر استان گيلان (با ميانگين سن 52/0 ± 6/16 سال، قد 16/9 ± 9/172 سانتيمتر، وزن 33/10 ± 90/68 كيلوگرم و چربي بدن 3/6 ± 66/11 درصد) به صورت هدفدار انتخاب شدند. آزمودنیها به روش متقاطع متعادل، طی دو جلسه با فاصله 4 روز از یکدیگر به صورت دو سوي كور، 6 میلیگرم به ازای هر کیلوگرم وزن بدن نوشابه انرژيزا و دارونما (15 دقيقه قبل از آزمون) مصرف كردند. در اين جلسات آزمودنيها پس از صرف صبحانه استاندارد در آزمونهای یک تکرار بیشینه و 60٪ یک تکرار بیشینه در حرکات پرس سینه و پرس پا، آزمون بیهوازی Rast، 45 متر سرعت، چابکی ایلینویز و آزمون هوازی 20 متر شاتل ران شركت نمودند. همچنين قبل، بلافاصله و 5 دقيقه بعد از آزمون Rast، مقدار 5 سيسي خون از سياهرگ بازويي، براي سنجش لاكتات خون اخذ و نتايج آن ثبت شد. برای تجزیه و تحلیل دادهها از نرم افزار SPSS نسخه20 و آزمون t همبسته استفاده شد. نتایج نشان داد عملکرد هوازی در مصرف کنندگان نوشابه انرژیزا به صورت معناداری بهبود یافت (05/0> P)، درحالیکه تغييرات در قدرت، استقامت عضلاني، سرعت، چابكي و توان بيهوازي بين مصرف کنندگان نوشیدنی انرژیزا و دارونما معنادار نبود (05/0< P). همچنين، تغييرات معناداری بین نوشیدنی انرژیزا و دارونما در سطوح لاكتات خون قبل، بلافاصله و 5 دقيقه بعد از آزمون مشاهده نشد (05/0 < P). به نظر می¬رسد مصرف حاد نوشابه انرژيزاي هايپ تاثیر معناداری بر شاخصهای عملکردی و لاکتات خون بدمینتونبازان ندارد و فقط باعث بهبود عملکرد هوازی آنها میشود.
The demand for improved performance and body composition changes have motivated the intake of nutritional ergogenic resources (REN) in athletes, promoting the indiscriminate use of these substances without a proper prescription. The aim of this study was to determine the prevalence of use, the level of knowledge and information sources on anabolic steroid (EA) and REN in a sample of 351 athletes, over 18 years, the city of Viçosa-MG, by semi-structured self-administered. The use of REN was reported by 74% of the sample being male athletes (80%) make more use of these supplements, compared to women (71%). Commonly used supplements were creatine (43.5%), maltodextrin (40%), whey protein (39.5), bebidade carbohydrate (39%) and albumin (45%), thus it is observed a high consumption of protein supplements. Moreover, this high intake of REN is not guided by a qualified professional, as most athletes consume these supplements without a prescription by a dietitian or doctor, putting health at risk. Although the sample has high education level, the information they possess on REN is questionable, since the main sources of information are the internet and friends. While these athletes have knowledge about the harmful effects of anabolic steroids, there was a prevalence of 45% in substance use. It was concluded that consumption of REN among athletes of Viçosa, MG is routine without a proper prescription professional, and that the level of knowledge about these REN is low.
Caffeine is a common substance in the diets of most athletes and it is now appearing in many new products, including energy drinks, sport gels, alcoholic beverages and diet aids. It can be a powerful ergogenic aid at levels that are considerably lower than the acceptable limit of the International Olympic Committee and could be beneficial in training and in competition. Caffeine does not improve maximal oxygen capacity directly, but could permit the athlete to train at a greater power output and/or to train longer. It has also ben shown to increase speed and/or power output in simulated race conditions. These effects have been found in activities that last as little as 60 seconds or as long as 2 hours. There is less information about the effects of caffeine on strength; however, recent work suggests no effect on maximal ability, but enhanced endurance or resistance to fatigue. There is no evidence that caffeine ingestion before exercise leads to dehydration, ion imbalance, or any other adverse effects. The ingestion of caffeine as coffee appears to be ineffective compared to doping with pure caffeine. Related compounds such as theophylline are also potent ergogenic aids. Caffeine may act synergistically with other drugs including ephedrine and anti-inflammatory agents. It appears that male and female athletes have similar caffeine pharmacokinetics, i.e., for a given dose of caffeine, the time course and absolute plasma concentrations of caffeine and its metabolites are the same. In addition, exercise or dehydration does not affect caffeine pharmacokinetics. The limited information available suggests that caffeine non-users and users respond similarly and that withdrawal from caffeine may not be important. The mechanism(s) by which caffeine elicits its ergogenic effects are unknown, but the popular theory that it enhances fat oxidation and spares muscle glycogen has very little support and is an incomplete explanation at best. Caffeine may work, in part, by creating a more favourable intracellular ionic environment in active muscle. This could facilitate force production by each motor unit.
Int J Exerc Sci 4(2) : 141-151, 2011. The use of caffeine-containing (74-mg) energy patches (EnP) offers a novel mode of caffeine delivery that may alleviate stomach discomfort associated with oral caffeine use. The purpose of this study was to use four separate tests to evaluate the effects of EnP use on aerobic and anaerobic exercise performance. Three separate moderately active college-aged sample populations performed either 1) cycle time-to-exhaustion (n = 9), 2) Wingate (WIN; n = 13), or 3) repeated sprints and one repetition maximum bench press (n = 10) using EnP and placebo patches (PlP). No statistical differences were found between EnP and PlP for all dependent variables (p > 0.05) except for WIN peak power, which showed a statistically significant decrease (p = 0.04). The dose of caffeine topically applied via an EnP may not have been enough to elicit an ergogenic effect on exercise performance. A dose of caffeine greater than 74-mg may be needed to produce an ergogenic effect. Further research is needed to investigate the delivery kinetics of transdermal caffeine in large dosages along with blood caffeine concentrations during and after exercise.
The effect of a pre-workout energy supplement on acute multijoint resistance exercise was examined in eight resistancetrained college-age men. Subjects were randomly provided either a placebo (P) or a supplement (S: containing caffeine, taurine, glucuronolactone, creatine, β-alanine, and the amino acids; leucine, isoleucine, valine, glutamine and arginine) 10 minutes prior to resistance exercise. Subjects performed 4 sets of no more than 10 repetitions of either barbell squat or bench press at 80% of their pre-determined 1 repetition-maximum (1RM) with 90 seconds of rest between sets. Dietary intake 24 hours prior to each of the two training trials was kept constant. Results indicate that consuming the pre-workout energy drink 10 minutes prior to resistance exercise enhances performance by significantly increasing the number of repetitions successfully performed (p = 0.022) in S (26.3 ± 9.2) compared to P (23.5 ± 9.4). In addition, the average peak and mean power performance for all four sets was significantly greater in S compared to P (p < 0.001 and p < 0.001, respectively). No differences were observed between trials in subjective feelings of energy during either pre (p = 0.660) or post (p = 0.179) meaures. Similary, no differences between groups, in either pre or post assessments, were observed in subjective feelings of focus (p = 0.465 and p = 0.063, respectively), or fatigue (p = 0.204 and p = 0.518, respectively). Results suggest that acute ingestion of a highenergy supplement 10 minutes prior to the onset of a multi-joint resistance training session can augment training volume and increase power performance during the workout.
This study measured athletes’ alcohol, energy drink, and combined-use. It also compared athletes’ reported risk-taking and consequences while using alcohol-only and in combination with energy drinks. From the total sample of 401 intercollegiate student-athletes, 315 (78%) used alcohol, 150 (37%) combined alcohol with energy drinks, and 194 (48%) used energy drinks (EDs) without alcohol. Ninety-two percent of drinkers participated in binge drinking. Sixty-one percent of combined users participated in high risk “energy binge” drinking episodes (using 3+ EDs on one occasion). Results indicated combined users (n = 150) consumed significantly more alcohol and had riskier drinking habits (e.g., heavy binge drinking) than athletes who used alcohol only (n = 165). The combined use of alcohol and energy drinks could potentially contribute to increased risk-taking and negative consequences. Results suggest a possible need to include information about energy drinks in existing athlete alcohol education and prevention programs.
RECENT RESEARCH HAS INDICATED THAT ENERGY DRINKS ARE THE MOST POPULAR SUPPLEMENT BESIDES MULTIVITAMINS IN THE AMERICAN ADOLESCENT AND YOUNG ADULT POPULATION. MORE THAN 30% OF ALL AMERICAN MALE AND FEMALE ADOLESCENTS USE THESE SUPPLEMENTS ON A REGULAR BASIS. ENERGY DRINKS ARE ALSO REPORTED TO BE THE MOST POPULAR SUPPLEMENT (41.7% OF THE 403 ATHLETES SURVEYED) AMONG YOUNG (17.7 ± 2.0 YEARS) ELITE BRITISH ATHLETES. THIS BRIEF REVIEW WILL EXAMINE THE EFFICACY OF THESE ENERGY DRINKS REGARDING PERFORMANCE IMPROVEMENTS AND METABOLIC ENHANCEMENT. IN ADDITION, ISSUES RELATING TO THE SAFETY OF ENERGY DRINK CONSUMPTION WILL ALSO BE DISCUSSED.
In this study we tested the hypothesis that caffeine supplementation improves neuromuscular function, which has both nutritional and clinical relevance.
Fourteen male subjects (mean ± SD: 23.8 ± 2.8 years) volunteered in a double-blind, repeated-measures study with placebo (PLA) or caffeine (CAFF) (6 mg kg(-1)). Maximal voluntary isometric contractions (MVCs), evoked maximal twitch, and maximal isokinetic contractions during elbow flexion were assessed. Mechanical and electromyographic (EMG) signals from the biceps brachii muscle were recorded, and muscle fiber conduction velocity (CV) was calculated to evaluate changes in the muscle force-velocity relationship and muscle fiber recruitment.
The torque-angular velocity curve was enhanced after CAFF supplementation. This was supported by a concomitant increase of CV values (8.7% higher in CAFF).
Caffeine improves muscle performance during short-duration maximal dynamic contractions. The concomitant improvement of mean fiber CV supports the hypothesis of an effect of caffeine on motor unit recruitment.
To review the effects, adverse consequences, and extent of energy drink consumption among children, adolescents, and young adults.
We searched PubMed and Google using "energy drink," "sports drink," "guarana," "caffeine," "taurine," "ADHD," "diabetes," "children," "adolescents," "insulin," "eating disorders," and "poison control center" to identify articles related to energy drinks. Manufacturer Web sites were reviewed for product information.
According to self-report surveys, energy drinks are consumed by 30% to 50% of adolescents and young adults. Frequently containing high and unregulated amounts of caffeine, these drinks have been reported in association with serious adverse effects, especially in children, adolescents, and young adults with seizures, diabetes, cardiac abnormalities, or mood and behavioral disorders or those who take certain medications. Of the 5448 US caffeine overdoses reported in 2007, 46% occurred in those younger than 19 years. Several countries and states have debated or restricted energy drink sales and advertising.
Energy drinks have no therapeutic benefit, and many ingredients are understudied and not regulated. The known and unknown pharmacology of agents included in such drinks, combined with reports of toxicity, raises concern for potentially serious adverse effects in association with energy drink use. In the short-term, pediatricians need to be aware of the possible effects of energy drinks in vulnerable populations and screen for consumption to educate families. Long-term research should aim to understand the effects in at-risk populations. Toxicity surveillance should be improved, and regulations of energy drink sales and consumption should be based on appropriate research.
The aim of this study was to investigate the effects of acute caffeine ingestion on intermittent high-intensity sprint performance after 5 days of creatine loading. After completing a control trial (no ergogenic aids, CON), twelve physically active men were administered in a double-blind, randomized crossover protocol to receive CRE + PLA (0.3 g kg(-1) day(-1) of creatine for 5 days then followed by 6 mg kg(-1) of placebo) and CRE + CAF (0.3 g kg(-1) day(-1) of creatine for 5 days and followed by 6 mg kg(-1) of caffeine), after which they performed a repeated sprint test. Each test consisted of six 10-s intermittent high-intensity sprints on a cycling ergometer, with 60-s rest intervals between sprints. Mean power, peak power, rating of perceived exertion (RPE), and heart rates were measured during the test. Blood samples for lactate, glucose, and catecholamine concentrations were drawn at specified intervals. The mean and peak power observed in the CRE + CAF were significantly higher than those found in the CON during Sprints 1 and 3; and the CRE + CAF showed significantly higher mean and peak power than that in the CRE + PLA during Sprints 1 and 2. The mean and peak power during Sprint 3 in the CRE + PLA was significantly greater than that in the CON. Heart rates, plasma lactate, and glucose increased significantly with CRE + CAF during most sprints. No significant differences were observed in the RPE among the three trials. The present study determined that caffeine ingestion after creatine supplements augmented intermittent high-intensity sprint performance.
Caffeine ingestion has been demonstrated to increase physical performance in some situations. This study examined the ability of a commercial energy drink containing caffeine to enhance acceleration tolerance and strength under G load.
Eight experienced centrifuge subjects completed three separate experimental acceleration exposures following ingestion of 11.5 ml x kg(-1) bodyweight of (1) a commercial energy drink, providing 5.0 mg caffeine/kg bodyweight; (2) a commercial energy drink without caffeine; or 3) a placebo. The acceleration exposures consisted of a relaxed gradual onset run to peripheral light loss, a rapid onset run to 6 G for 15 s, and a simulated air combat maneuver (SACM) run of repeated alternations between 4.5 G for 15 s and 7 G for 15 s until volitional exhaustion.
Relaxed G tolerance was 13% higher under the caffeinated energy drink session, whereas SACM duration did not differ among the drink conditions. Hip adductor muscle strength was 37% lower during the placebo session than during the other two sessions.
Consumption of a caffeine-based energy drink may enhance relaxed G tolerance and may increase strength, but does not impact acceleration tolerance duration.
This investigation reports the effects of caffeinated chewing gum on fatigue and hormone response during repeated sprint performance with competitive cyclists. Nine male cyclists (mean ± SD, age 24 ± 7 years, VO(2max) 62.5 ± 5.4 mL kg(-1) min(-1)) completed four high-intensity experimental sessions, consisting of four sets of 30 s sprints (5 sprints each set). Caffeine (240 mg) or placebo was administered via chewing gum following the second set of each experimental session. Testosterone and cortisol concentrations were assayed in saliva samples collected at rest and after each set of sprints. Mean power output in the first 10 sprints relative to the last 10 sprints declined by 5.8 ± 4.0% in the placebo and 0.4 ± 7.7% in the caffeine trials, respectively. The reduced fatigue in the caffeine trials equated to a 5.4% (90% confidence limit ±3.6%, effect size 0.25; ±0.16) performance enhancement in favour of caffeine. Salivary testosterone increased rapidly from rest (~53%) and prior to treatments in all trials. Following caffeine treatment, testosterone increased by a further 12 ± 14% (ES 0.50; ± 0.56) relative to the placebo condition. In contrast, cortisol concentrations were not elevated until after the third exercise set; following the caffeine treatment cortisol was reduced by 21 ± 31% (ES -0.30; ± 0.34) relative to placebo. The acute ingestion of caffeine via chewing gum attenuated fatigue during repeated, high-intensity sprint exercise in competitive cyclists. Furthermore, the delayed fatigue was associated with substantially elevated testosterone concentrations and decreased cortisol in the caffeine trials.
The purpose of this study was to compare the effects of a carbohydrate-electrolyte plus caffeine, carnitine, taurine, and B vitamins solution (CE+) and a carbohydrate-electrolyte-only solution (CE) vs. a placebo solution (PLA) on cycling performance and maximal voluntary contraction (MVC). In a randomized, double-blind, crossover, repeated-measures design, 14 male cyclists (M +/- SD age 27 +/- 6 yr, VO2max 60.4 +/- 6.8 ml x kg-1 x min(-1)) cycled for 120 min submaximally (alternating 61% +/- 5% and 75% +/- 5% VO2max) and then completed a 15-min performance trial (PT). Participants ingested CE+, CE, or PLA before (6 ml/kg) and every 15 min during exercise (3 ml/kg). MVC was measured as a single-leg isometric extension (70 degree knee flexion) before (pre) and after (post) exercise. Rating of perceived exertion (RPE) was measured throughout. Total work accumulated (KJ) during PT was greater (p < .05) in CE+ (233 +/- 34) than PLA (205 +/- 52) but not in CE (225 +/- 39) vs. PLA. MVC (N) declined (p < .001) from pre to post in PLA (988 +/- 213 to 851 +/- 191) and CE (970 +/- 172 to 870 +/- 163) but not in CE+ (953 +/- 171 to 904 +/- 208). At Minutes 60, 90, 105, and 120 RPE was lower in CE+ (14 +/- 2, 14 +/- 2, 12 +/- 1, 15 +/- 2) than in PLA (14 +/- 2, 15 +/- 2, 14 +/- 2, 16 +/- 2; p < .001). CE+ resulted in greater total work than PLA. CE+, but not PLA or CE, attenuated pre-to-post MVC declines. Performance increases during CE+ may have been influenced by lower RPE and greater preservation of leg strength during exercise in part as a result of the hypothesized effects of CE+ on the central nervous system and skeletal muscle.
Research has indicated that low-to-moderate dosages of caffeine supplementation are ergogenic for sustained endurance efforts as well as high-intensity exercise. The effects of caffeine supplementation on strength-power performance are equivocal, with some studies indicating a benefit and others demonstrating no change in performance. The majority of research that has examined the effects of caffeine supplementation on strength-power performance has been carried out in both trained and untrained men. Therefore, the purpose of this study was to determine the acute effects of caffeine supplementation on strength and muscular endurance in resistance-trained women.
In a randomized manner, 15 women consumed caffeine (6 mg/kg) or placebo (PL) seven days apart. Sixty min following supplementation, participants performed a one-repetition maximum (1RM) barbell bench press test and repetitions to failure at 60% of 1RM. Heart rate (HR) and blood pressure (BP) were assessed at rest, 60 minutes post-consumption, and immediately following completion of repetitions to failure.
Repeated measures ANOVA indicated a significantly greater bench press maximum with caffeine (p </= 0.05) (52.9 +/- 11.1 kg vs. 52.1 +/- 11.7 kg) with no significant differences between conditions in 60% 1RM repetitions (p = 0.81). Systolic blood pressure was significantly greater post-exercise, with caffeine (p < 0.05) (116.8 +/- 5.3 mmHg vs. 112.9 +/- 4.9 mmHg).
These findings indicate a moderate dose of caffeine may be sufficient for enhancing strength performance in resistance-trained women.
Position Statement: The position of The Society regarding caffeine supplementation and sport performance is summarized by the following seven points: 1.) Caffeine is effective for enhancing sport performance in trained athletes when consumed in low-to-moderate dosages (~3-6 mg/kg) and overall does not result in further enhancement in performance when consumed in higher dosages (>/= 9 mg/kg). 2.) Caffeine exerts a greater ergogenic effect when consumed in an anhydrous state as compared to coffee. 3.) It has been shown that caffeine can enhance vigilance during bouts of extended exhaustive exercise, as well as periods of sustained sleep deprivation. 4.) Caffeine is ergogenic for sustained maximal endurance exercise, and has been shown to be highly effective for time-trial performance. 5.) Caffeine supplementation is beneficial for high-intensity exercise, including team sports such as soccer and rugby, both of which are categorized by intermittent activity within a period of prolonged duration. 6.) The literature is equivocal when considering the effects of caffeine supplementation on strength-power performance, and additional research in this area is warranted. 7.) The scientific literature does not support caffeine-induced diuresis during exercise, or any harmful change in fluid balance that would negatively affect performance.
Our objective was to perform a systematic review and meta-analysis of the research literature assessing the effect of caffeine ingestion on maximal voluntary contraction (MVC) strength and muscular endurance.
Thirty-four relevant studies between 1939 and 2008 were included in the meta-analyses of caffeine's effects on MVC strength (n = 27 studies) and muscular endurance (n = 23 studies). Effect sizes (ES) were calculated as the standardized mean difference and meta-analyses were completed using a random-effects model.
Overall, caffeine ingestion was found to result in a small beneficial effect on MVC strength (overall ES = 0.19, P = 0.0003). However, caffeine appears to improve MVC strength primarily in the knee extensors (i.e., by approximately 7%, ES = 0.37) and not in other muscle groups such as the forearm or the knee flexors. In an attempt to offer a physiological mechanism behind caffeine's ability to improve MVC strength, a meta-analysis was run on ES from nine studies that measured percent muscle activation during MVC in trials comparing caffeine versus placebo; the overall ES (0.67) was highly significant (P = 0.00008) and of moderate to large size, thus implicating an effect of caffeine on the CNS. Caffeine ingestion was also found to exert a small beneficial effect on muscular endurance (overall ES = 0.28, P = 0.00005). However, it appears caffeine improves muscular endurance only when it is assessed using open (i.e., by approximately 18%, ES = 0.37) and not fixed end point tests.
Overall, caffeine ingestion improves MVC strength and muscular endurance. The effect on strength appears exclusively in the knee extensors, and the effect on muscular endurance appears only detectable with open end point tests.
The purpose of this study was to test the hypothesis that prior caffeine ingestion would enhance neural recovery after isometric fatiguing maximal intermittent plantar flexions, and thus would enhance the recovery of voluntary muscle strength. After a familiarisation session, 13 males randomly participated in two experimental trials where they ingested either caffeine (approximately 6 mg/kg) or identical placebo pills 1 h prior to testing. Subjects were tested for electromyogram (EMG) activity and evoked V-waves in the soleus and gastrocnemius medialis muscles. These measurements were obtained during brief plantar flexion maximum voluntary isometric contractions (MVICs), and normalised by the superimposed maximal M-wave (EMG/M(SUP) and V/M(SUP), respectively), before and after (20 s, 10 min and 20 min) a fatigue protocol (seven 25 s MVICs, 5 s rest). There were no effects (P > 0.05) of caffeine ingestion on EMG/M(SUP), V/M(SUP), MVIC or M(SUP). The central neural modulation (EMG/M(SUP) and V/M(SUP)) and voluntary strength changes followed a similar time-course with a substantial reduction 20 s post-fatigue and a gradual return towards baseline values.
The purpose of this work was to determine the effects of caffeine on high intensity time trial (TT) cycling performance in well-trained subjects.
Six male cyclists with the following physical characteristics (mean +/- SD) age 30.7 +/- 12, height 179.3 +/- 7.5 cm, mass 70.0 +/- 7.5 kg, VO2max 65.0 +/- 6.3 mL.kg-1.min-1 undertook three 1-h TT performances, control (C), placebo (P) and caffeine (CAF), on a Velotron cycle ergometer conducted in a double-blind, random fashion. Subjects rested for 60 min and were then given CAF or P in a dose of 6 mg.kg-1 body mass and then commenced exercise after another 60 min of rest. Before ingestion, 60 min postingestion, and at the end of the TT, finger-prick blood samples were analyzed for lactate.
The cyclists rode significantly further in the CAF trial (28.0 +/- 1.3 km) than they did in the C (26.3 +/- 1.5 km, P < .01) or P (26.4 +/- 1.5 km, P < .02) trials. No differences were seen in heart rate data throughout the TT (P > .05). Blood lactate levels were significantly higher at the end of the trials than either at rest or postingestion (P < .0001), but there were no differences between the three trial groups.
On the basis of the data, we concluded that performance was improved with the use of a caffeine supplement.
The purpose of this study was to examine the effect of a pre-exercise high energy drink on reaction time and anaerobic power in competitive strength/power athletes. In addition, the effect of the pre-exercise drink on subjective feelings of energy, fatigue, alertness and focus was also explored.
Twelve male strength/power athletes (21.1 +/- 1.3 y; 179.8 +/- 7.1 cm; 88.6 +/- 12.1 kg; 17.6 +/- 3.3% body fat) underwent two testing sessions administered in a randomized and double-blind fashion. During each session, subjects reported to the Human Performance Laboratory and were provided with either 120 ml of a high energy drink (SUP), commercially marketed as Redline Extreme(R) or 120 ml of a placebo (PL) that was similar in taste and appearance but contained no active ingredients. Following consumption of the supplement or placebo subjects rested quietly for 10-minutes prior to completing a survey and commencing exercise. The survey consisted of 4 questions asking each subject to describe their feelings of energy, fatigue, alertness and focus for that moment. Following the completion of the questionnaire subjects performed a 2-minute quickness and reaction test on the Makoto testing device (Makoto USA, Centennial CO) and a 20-second Wingate Anaerobic Power test. Following a 10-minute rest subjects repeated the testing sequence and after a similar rest period a third and final testing sequence was performed. The Makoto testing device consisted of subjects reacting to both a visual and auditory stimulus and striking one out of 30 potential targets on three towers.
Significant difference in reaction performance was seen between SUP and PL in both average number of targets struck (55.8 +/- 7.4 versus 51.9 +/- 7.4, respectively) and percent of targets struck (71.9 +/- 10.5% versus 66.8 +/- 10.9%, respectively). No significant differences between trials were seen in any anaerobic power measure. Subjective feelings of energy (3.5 +/- 0.5 versus 3.1 +/- 0.5) and focus (3.8 +/- 0.5 versus 3.3 +/- 0.7) were significantly higher during SUP compared to PL, respectively. In addition, a trend towards an increase in average alertness (p = 0.06) was seen in SUP compared to P.
Results indicate a significant increase in reaction performance, with no effect on anaerobic power performance. In addition, ingestion of this supplement significantly improves subjective feelings of focus and energy in male strength/power athletes.
Athletes are among the groups of people who are interested in the effects of caffeine on endurance and exercise capacity. Although many studies have investigated the effect of caffeine ingestion on exercise, not all are suited to draw conclusions regarding caffeine and sports performance. Characteristics of studies that can better explore the issues of athletes include the use of well-trained subjects, conditions that reflect actual practices in sport, and exercise protocols that simulate real-life events. There is a scarcity of field-based studies and investigations involving elite performers. Researchers are encouraged to use statistical analyses that consider the magnitude of changes, and to establish whether these are meaningful to the outcome of sport. The available literature that follows such guidelines suggests that performance benefits can be seen with moderate amounts (~3mgkg¹ body mass) of caffeine. Furthermore, these benefits are likely to occur across a range of sports, including endurance events, stop-and-go events (e.g., team and racquet sports), and sports involving sustained high-intensity activity lasting from 160min (e.g., swimming, rowing, and middle and distance running races). The direct effects on single events involving strength and power, such as lifts, throws, and sprints, are unclear. Further studies are needed to better elucidate the range of protocols (timing and amount of doses) that produce benefits and the range of sports to which these may apply. Individual responses, the politics of sport, and the effects of caffeine on other goals, such as sleep, hydration, and refuelling, also need to be considered.
Caffeine, an adenosine receptor antagonist, has been studied for decades as a putative ergogenic aid. In the past 2 decades, the information has overwhelmingly demonstrated that it indeed is a powerful ergogenic aid, and frequently theories have been proposed that this is due to alterations in fat and carbohydrate metabolism. While caffeine certainly mobilizes fatty acids from adipose tissue, rarely have measures of the respiratory exchange ratio indicated an increase in fat oxidation. However, this is a difficult measure to perform accurately during exercise, and small changes could be physiologically important. The few studies examining human muscle metabolism directly have also supported the fact that there is no change in fat or carbohydrate metabolism, but these usually have had a small sample size. We combined the data from muscle biopsy analyses of several similar studies to generate a sample size of 1644, depending on the measure. We examined muscle glycogen, citrate, acetyl-CoA, glucose-6-phosphate, and cyclic adenosine monophosphate (cAMP) in resting samples and in those obtained after 1015min of exercise at 70%85% maximal oxygen consumption. Exercise decreased (p< 0.05) glycogen and increased (p< 0.05) citrate, acetyl-CoA, and glucose-6-phosphate. The only effects of caffeine were to increase (p< 0.05) citrate in resting muscle and cAMP in exercise. There is very little evidence to support the hypothesis that caffeine has ergogenic effects as a result of enhanced fat oxidation. Individuals may, however, respond differently to the effects of caffeine, and there is growing evidence that this could be explained by common genetic variations.
Nine trained cyclists were studied to determine the effects of caffeine (CAF), and glucose polymer (GP) feedings on work production (kpm) during two hr of isokinetic cycling exercise (80 rpm). Ingestion of 250 mg of CAF 60 min prior to the ride was followed by ingestion of an additional 250 mg fed at 15 min intervals over the first 90 min of the exercise. This treatment significantly increased work production by 7.4% and Vo2 by 7.3% as compared to control (C) while the subjects' perception of exertion remained unchanged. Ingestion of approximately 90 g of GP during the first 90 min (12.8 g/15 min) of the exercise had no effect on total work production or Vo2. It was, however, effective in reducing the rate of fatigue over the last 30 min of cycling. Although GP maintained blood glucose and insulin levels (P less than or equal to 0.05) above those of the C and CAF trials, total CHO utilization did not differ between treatments. During the last 70 min of the CAF trial, however, fat oxidation was elevated 31% and appeared to provide the substrate needed for the increased work production during this period of exercise. These data, therefore, demonstrate an enhanced rate of lipid catabolism and work production following the ingestion of caffeine.
The influence of specific training on benefits from caffeine (Caf) ingestion was examined during a sprint test in a group of highly trained swimmers (T) and compared with the response of a group of untrained occasional swimmers (UT). Seven T and seven UT subjects swam freestyle two randomly assigned 2 x 100 m distances, at maximal speed and separated by 20 min of passive recovery, once after Caf (250 mg) and once after placebo (Pla) ingestion. Anaerobic capacity was assessed by the mean velocity (meters per second) during each 100 m and blood was sampled from the fingertip just before and 1, 3, 5, 7, and 9 min after each 100 m for resting and maximal blood lactate concentration ([la-]b,max) determination. The [la-]bmax was significantly enhanced by Caf in both T and UT subjects (P less than 0.01). However, only T subjects exhibited significant improvement in their swimming velocity (P less than 0.01) after Caf or any significant impairment during the second 100 m. In light of these results, it appears that specific training is necessary to benefit from the metabolic adaptations induced by Caf during supramaximal exercise requiring a high anaerobic capacity.
The present study examined whether a high caffeine dose improved running and cycling performance and altered substrate metabolism in well-trained runners. Seven trained competitive runners [maximal O2 uptake (VO2max) 72.6 +/- 1.5 ml.kg-1.min-1] completed four randomized and double-blind exercise trials at approximately 85% VO2max; two trials running to exhaustion and two trials cycling to exhaustion. Subjects ingested either placebo (PL, 9 mg/kg dextrose) or caffeine (CAF, 9 mg/kg) 1 h before exercise. Endurance times were increased (P less than 0.05) after CAF ingestion during running (PL 49.2 +/- 7.2 min, CAF 71.0 +/- 11.0 min) and cycling (PL 39.2 +/- 6.5 min, CAF 59.3 +/- 9.9 min). Plasma epinephrine concentration [EPI] was increased (P less than 0.05) with CAF before running (0.22 +/- 0.02 vs. 0.44 +/- 0.08 nM) and cycling (0.31 +/- 0.06 vs. 0.45 +/- 0.06 nM). CAF ingestion also increased [EPI] (P less than 0.05) during exercise; PL and CAF values at 15 min were 1.23 +/- 0.13 and 2.51 +/- 0.33 nM for running and 1.24 +/- 0.24 and 2.53 +/- 0.32 nM for cycling. Similar results were obtained at exhaustion. Plasma norepinephrine was unaffected by CAF at rest and during exercise. CAF ingestion also had no effect on respiratory exchange ratio or plasma free fatty acid data at rest or during exercise. Plasma glycerol was elevated (P less than 0.05) by CAF before exercise and at 15 min and exhaustion during running but only at exhaustion during cycling. Urinary [CAF] increased to 8.7 +/- 1.2 and 10.0 +/- 0.8 micrograms/ml after the running and cycling trials.(ABSTRACT TRUNCATED AT 250 WORDS)
Single-dose oral administration of 100 mg caffeine increased the resting metabolic rate of both lean and postobese human volunteers by 3-4% (p less than 0.02) over 150 min and improved the defective diet-induced thermogenesis observed in the postobese subjects. Measurements of energy expenditure (EE) in a room respirometer indicate that repeated caffeine administration (100 mg) at 2-h intervals over a 12-h day period increased the EE of both subject groups by 8-11% (p less than 0.01) during that period but had no influence on the subsequent 12-h night EE. The net effect was a significant increase (p less than 0.02) in daily EE of 150 kcal in the lean volunteers and 79 kcal in the postobese subjects. Caffeine at commonly consumed doses can have a significant influence on energy balance and may promote thermogenesis in the treatment of obesity.
The effect of different dosages of caffeine (0-5-9-13 mg.kg body weight-1) on endurance performance was examined. Nine well-trained cyclists participated in this study (VO2max 65.1 +/- 2.6 ml.kg-1.min-1). Caffeine capsules were administered in random order and double-blind. One hour after capsule ingestion, subjects cycled until exhaustion at 80% Wmax on an electromagnetically braked cycle ergometer. Blood samples were taken before, during and after the exercise test. Before and after the test a urine sample was obtained. A significant increase in endurance performance was found for all caffeine tests compared to placebo (endurance time 47 +/- 13, 58 +/- 11, 59 +/- 12 and 58 +/- 12 min for 0, 5, 9 and 13 mg.kg-1 body weight, respectively). No differences were found in endurance performance between the three caffeine dosages which indicates that no dose-response relation of caffeine and endurance performance was found. An increased free fatty acid and glycerol concentration was found after caffeine consumption compared with placebo. The mean urinary caffeine concentrations after exercise were 4.8 +/- 1.8, 8.9 +/- 5.2 and 14.9 +/- 6.9 micrograms.ml-1 urine for 5, 9 and 13 mg of caffeine.kg-1 body weight. Only the lowest dose of caffeine resulted in urine caffeine concentrations below the doping limit of the International Olympic Committee of 12 micrograms.ml-1 urine in all individuals. It is concluded that caffeine is an ergogenic aid that stimulates endurance performance. A dose-response relation between caffeine and endurance time was not found for the dose-range investigated.(ABSTRACT TRUNCATED AT 250 WORDS)
This study examined the exercise responses of well-trained endurance athletes to various doses of caffeine to evaluate the impact of the drug on exercise metabolism and endurance capacity. Subjects (n = 8) withdrew from all dietary sources of caffeine for 48 h before each of four tests. One hour before exercise they ingested capsules of placebo or caffeine (3, 6, or 9 mg/kg), rested quietly, and then ran at 85% of maximal O2 consumption to voluntary exhaustion. Blood samples for methylxanthine, catecholamine, glucose, lactate, free fatty acid, and glycerol analyses were taken every 15 min. Plasma caffeine concentration increased with each dose (P < 0.05). Its major metabolite, paraxanthine, did not increase between the 6 and 9 mg/kg doses, suggesting that hepatic caffeine metabolism was saturated. Endurance was enhanced with both 3 and 6 mg/kg of caffeine (increases of 22 +/- 9 and 22 +/- 7%, respectively; both P < 0.05) over the placebo time of 49.4 +/- 4.2 min, whereas there was no significant effect with 9 mg/kg of caffeine. In contrast, plasma epinephrine was not increased with 3 mg/kg of caffeine but was greater with the higher doses (P < 0.05). Similarly only the highest dose of caffeine resulted in increases in glycerol and free fatty acids (P < 0.05). Thus the highest dose had the greatest effect on epinephrine and blood-borne metabolites yet had the least effect on performance. The lowest dose had little or no effect on epinephrine and metabolites but did have an ergogenic effect. These results are not compatible with the traditional theory that caffeine mediates its ergogenic effect via enhanced catecholamines.
Carrier Air Wing FIVE (U.S.S. Independence) sustained and continuous operations during the onset of Operation Southern Watch provided an opportunity to evaluate fatigue and responses to fatigue in naval aviation aircrew personnel. We compiled U.S. Navy Carrier Air Wing Five (CVW-5) aircrew subjective fatigue reports during and immediately after the 18 d of intensive carrier aviation operations enforcing the "No Fly Zone" over southern Iraq. This survey provided indicators for monitoring fatigue during patrols of 5-6 hours. Also addressed are the most commonly used methods to combat fatigue, including caffeine tablets and nicotine gum.
The effect of addition of different dosages of caffeine (Caf) to a carbohydrate-electrolyte solution (CES) on metabolism, Caf excretion, and performance was examined. Subjects (n = 15) ingested 8 ml/kg of water placebo (Pla-W), 7% CES (Pla-CES), or 7% CES with 150, 225, and 320 mg/l Caf (CES-150, CES-225, and CES-320, respectively) during a warm-up protocol (20 min) and 3 ml/kg at one-third and two-thirds of a 1-h time trial. Performance was improved with Caf supplementation: 62.5 +/- 1.3, 61.5 +/- 1.1, 60.4 +/- 1.0, 58.9 +/- 1.0, and 58.9 +/- 1.2 min for Pla-W, Pla-CES, CES-150, CES-225, and CES-320, respectively. The postexercise urinary Caf concentration (range 1.3-2.5 microg/ml) was dose dependent and always far below the doping level of the International Olympic Committee (12 microg/ml) in all subjects. Sweat Caf excretion during exercise exceeded postexercise early-void urinary Caf excretion. Caffeinated CES did not enhance free fatty acid availability, ruling out the fact that performance improvement resulted from enhanced fat oxidation. It is concluded that addition of relatively low amounts of Caf to CES improves performance and that postexercise urinary Caf concentration remained low.
Caffeine (Caf) ingestion increases plasma epinephrine (Epi) and exercise endurance; these results are frequently transferred to coffee (Cof) consumption. We examined the impact of ingestion of the same dose of Caf in Cof or in water. Nine healthy, fit, young adults performed five trials after ingesting (double blind) either a capsule (Caf or placebo) with water or Cof (decaffeinated Cof, decaffeinated with Caf added, or regular Cof). In all three Caf trials, the Caf dose was 4.45 mg/kg body wt and the volume of liquid was 7.15 ml/kg. After 1 h of rest, the subject ran at 85% of maximal O2 consumption until voluntary exhaustion (approximately 32 min in the placebo and decaffeinated Cof tests). In the three Caf trials, the plasma Caf and paraxanthine concentrations were very similar. After 1 h of rest, the plasma Epi was increased (P < 0.05) by Caf ingestion, but the increase was greater (P < 0.05) with Caf capsules than with Cof. During the exercise there were no differences in Epi among the three Caf trials, and the Epi values were all greater (P < 0.05) than in the other tests. Endurance was only increased (P < 0. 05) in the Caf capsule trial; there were no differences among the other four tests. One cannot extrapolate the effects of Caf to Cof; there must be a component(s) of Cof that moderates the actions of Caf.
This Clinical Report was retired July 2021
Sports and energy drinks are being marketed to children and adolescents for a wide variety of inappropriate uses. Sports drinks and energy drinks are significantly different products, and the terms should not be used interchangeably. The primary objectives of this clinical report are to define the ingredients of sports and energy drinks, categorize the similarities and differences between the products, and discuss misuses and abuses. Secondary objectives are to encourage screening during annual physical examinations for sports and energy drink use, to understand the reasons why youth consumption is widespread, and to improve education aimed at decreasing or eliminating the inappropriate use of these beverages by children and adolescents. Rigorous review and analysis of the literature reveal that caffeine and other stimulant substances contained in energy drinks have no place in the diet of children and adolescents. Furthermore, frequent or excessive intake of caloric sports drinks can substantially increase the risk for overweight or obesity in children and adolescents. Discussion regarding the appropriate use of sports drinks in the youth athlete who participates regularly in endurance or high-intensity sports and vigorous physical activity is beyond the scope of this report.
This double-blind, placebo-controlled, within-subject experiment examined the effects of low-dose caffeine on pain reported during an exhaustive grip task. The grip task consisted of holding a metal block attached to standard Olympic weight plates with the arm at the side until the participants could no longer maintain their grip. Apparently healthy recreationally trained college-aged adults (men, n = 5; women, n = 5) were given either a piece of Stay Alert™ gum that delivered 85% of the effective dose of 100 mg of caffeine in 5 minutes or an identical placebo gum that contained no caffeine. Subsequently, pain perception and ratings of perceived exertion were recorded during an exhaustive grip task every 15 seconds and the overall time to exhaustion. No significant difference was found in time to exhaustion between treatments. A significant main effect of treatment for reported pain (p < 0.001, Φ = 0.377) was observed. Thus, in a population of recreationally trained college-aged adults, low-dose caffeine may attenuate the individual's perception of pain during a grip to exhaustion task.
The primary aim of the study was to determine the efficacy of acute caffeine intake to enhance intense resistance training performance. Fourteen resistance-trained men (age and body mass = 23.1 ± 1.1 years and 83.4 ± 13.2 kg, respectively) who regularly consumed caffeine ingested caffeine (6 mg · kg(-1)) or placebo 1 hour before completion of 4 sets of barbell bench press, leg press, bilateral row, and barbell shoulder press to fatigue at 70-80% 1-repetition maximum. Two minutes of rest was allotted between sets. Saliva samples were obtained to assess caffeine concentration. The number of repetitions completed per set and total weight lifted were recorded as indices of performance. Two-way analysis of variance with repeated measures was used to examine differences in performance across treatment and sets. Compared to placebo, there was a small but significant effect (p < 0.05) of acute caffeine intake on repetitions completed for the leg press but not for upper-body exercise (p > 0.05). Total weight lifted across sets was similar (p > 0.05) with caffeine (22,409.5 ± 3,773.2 kg) vs. placebo (21,185.7 ± 4,655.4 kg), yet there were 9 'responders' to caffeine, represented by a meaningful increase in total weight lifted with caffeine vs. placebo. Any ergogenic effect of caffeine on performance of fatiguing, total-body resistance training appears to be of limited practical significance. Additional research is merited to elucidate interindividual differences in caffeine-mediated improvements in performance.
This study examined the effects of acute caffeine ingestion on agility performance and decision-making accuracy after simulated team-sport exercise.
Using a randomized, double-blinded, counterbalanced design, 10 moderately trained male team-sport athletes ingested either caffeine (6 mg·kg(-1)) or placebo (dextrose) 60 min before completing an 80-min (4 × 20 min) simulated team-game, intermittent running protocol. Interspersed between each exercise quarter was a reactive agility test (RAT) consisting of five trials where measures of total time (TT), reactive agility (RA) time, decision time (DT), movement time (MT), and decision-making accuracy were obtained.
Although there were no significant differences between trials for TT (P = 0.54), RA time (P = 0.84), MT (P = 0.89), or DT (P = 0.91), caffeine ingestion resulted in consistently faster TT (2.3%), RA time (3.9%), MT (2.7%), and DT (9.3%) scores compared with placebo (significant main effect for condition for RA time, TT, DT, and MT; P < 0.05). These faster times were supported by qualitative analyses of "almost certain benefit" and large effect size (ES) for RA (quarter 3) and "likely" to "very likely benefits" and moderate to large ES for TT (precircuit and quarters 1, 2, and 4) and RA time (precircuit and quarters 1, 2 and 4). A "likely benefit" and moderate ES was found for MT (quarters 1 and 3), but the effect of caffeine on DT was largely "unclear," with small ES and only a "likely" chance of benefit (quarters 2 and 3). Improved decision-making accuracy (3.8%) after caffeine ingestion was supported by a "likely benefit" (quarter 1) and large ES (quarters 1 and 4).
Caffeine ingestion may be beneficial to RA performance when athletes are fresh and fatigued.
This study assessed the effects of caffeine on repeated sprint ability (RSA), reactive agility time (RAT), sleep and next day exercise performance.
Ten moderately trained male athletes (single-blind, randomized, crossover design) ingested either caffeine (6 mg.kg-1 bm) or placebo 1 h before exercise. Trials were performed on the same day one week apart. Performance measures included a RAT test (10 trials¥10.2 m, separated by 30 s), followed by 7 min of active recovery and then a RSA test (five sets of 6¥20 m sprints with 25 or 60 s of recovery). The RSA was then followed by 5 min of active recovery and another RAT. That night, participants wore a wrist sleep actigraph to bed. Next day, participants repeated the RAT and the first set of the RSA tests.
Significant improvements were demonstrated after caffeine ingestion compared to placebo for the combined total time of each set (TT; combined sets 1, 3, 5; 58.947±1.88 vs. 59.683±2.54 s, respectively; P=0.05), best sprint time (BT; next day performance; 3.176±0.10 vs. 3.230±0.12 s, respectively, P=0.01), and % decrement (combined sets 2, 4; 2.866±1.24 vs. 3.801±1.69 s, respectively; P=0.02). Moderate to strong effect sizes were found for % decrement for set 2 (Cohen's d=-0.82; 1.312±0.65 vs. 2.110±1.20 s for caffeine and placebo conditions, respectively) and for sets 2 and 4 combined (Cohen's d=-0.63; 2.866±1.24 vs. 3.801±1.69 for caffeine and placebo conditions, respectively). No significant differences were found for RAT or for sleep measures (P>0.05).
Caffeine improved RSA, including next day performance, but had little effect on RAT or sleep parameters.
Research has suggested that caffeine enhances aerobic performance. The evidence for high-intensity, short-term exercise, particularly resistance exercise is mixed and has not fully examined the psychological changes that occur after this mode of exercise with caffeine ingestion. This study examined the effect of caffeine (5 mg · kg(-1)) vs. placebo on bench press exercise to failure and the mood state response pre to postexercise. Thirteen moderately trained men (22.7 ± 6.0 years) completed 2 laboratory visits, after determination of 1 repetition maximum (1RM) on the bench press, where they performed bench press repetitions to failure at a load of 60% 1RM. Mood state was assessed 60 minutes pre and immediately post-substance ingestion. Borg's rating of perceived exertion (RPE) and peak blood lactate (PBla) were assessed after each test, and peak heart rate (PHR) was determined using heart rate telemetry. Participants completed significantly more repetitions to failure (p = 0.031) and lifted significantly greater weight (p = 0.027) in the caffeine condition compared to the placebo condition. The PHR (p = 0.0001) and PBla (p = 0.002) were higher after caffeine ingestion. The RPE was not different across conditions (p = 0.082). Mood state scores for vigor were greater (p = 0.001) and fatigue scores lower (p = 0.04) in the presence of caffeine. Fatigue scores were greater postexercise (p = 0.001) compared to scores pre exercise across conditions. Caffeine ingestion enhances performance in short-term, resistance exercise to failure and may favorably change the mood state response to exercise compared to a placebo.
Exercise is making a resurgence in many countries, given its benefits for fitness as well as prevention of obesity. This trend has spawned many supplements that purport to aid performance, muscle growth, and recovery. Initially, sports drinks were developed to provide electrolyte and carbohydrate replacement. Subsequently, energy beverages (EBs) containing stimulants and additives have appeared in most gyms and grocery stores and are being used increasingly by "weekend warriors" and those seeking an edge in an endurance event. Long-term exposure to the various components of EBs may result in significant alterations in the cardiovascular system, and the safety of EBs has not been fully established. For this review, we searched the MEDLINE and EMBASE databases from 1976 through May 2010, using the following keywords: energy beverage, energy drink, power drink, exercise, caffeine, red bull, bitter orange, glucose, ginseng, guarana, and taurine. Evidence regarding the effects of EBs is summarized, and practical recommendations are made to help in answering the patient who asks, "Is it safe for me to drink an energy beverage when I exercise?"
Preexercise nutritional investigations have recently become a popular avenue of examining the interaction of multiple ingredients on exercise and training methods. The critical velocity (CV) test is used to quantify the relationship between total running distance and time to exhaustion (TTE), yielding aerobic (CV) and anaerobic parameters (anaerobic running capacity [ARC]). The purpose of this study was to examine the hypothesis that a preexercise supplement containing caffeine, creatine, and amino acids (Game Time; Corr-Jen Laboratories Inc, Aurora, CO) would positively impact CV and ARC in college-aged men and women. In a single-blind crossover design, 10 participants consumed the preexercise supplement (ACT) or placebo (PL) before each testing session. Each participant completed runs to exhaustion on a treadmill at 110%, 90% (day 1), and 105% and 100% (day 2) of the peak velocity (PV) determined from a graded exercise test. The ACT elicited a 10.8% higher ARC (P = .02) compared with the PL, whereas no difference was found in CV (0.6%, P = .38). The TTE was greater for the ACT than the PL at 110% (ACT = 125.7 ± 9.6 seconds, PL = 117.3 ± 12.6 seconds), 105% (ACT = 156.9 ± 11.0 seconds, PL = 143.8 ± 12.9 seconds), and 100% PV (ACT = 185.7 ± 10.7 seconds, PL = 169.7 ± 12.8 seconds) (P = .01-.04); but there was no difference for the TTE at 90% PV (ACT = 353.5 ± 52.7 seconds, PL = 332.7 ± 54.0 seconds) (P = .08). These findings suggest that the acute ingestion of this preexercise supplement may be an effective strategy for improving anaerobic performance, but appears to have no effect on aerobic power.
Studies provide equivocal results regarding the ergogenic properties of caffeine during high-intensity exercise.
The primary aim of this study was to examine the effects of two doses of caffeine on peak/average torque, power output, and total work of the knee extensors and flexors during two bouts of high-intensity exercise.
Fifteen active men (mean age = 26.4 ± 3.9 yr and body mass = 82.7 ± 2.9 kg) initially completed a familiarization bout on the isokinetic dynamometer, followed by three subsequent trials separated by at least 48 h. Exercise consisted of two bouts of 40 repetitions of maximal knee extension and flexion of the dominant leg at a contraction velocity equal to 180°·s. Before each trial, subjects abstained from caffeine intake and intense exercise for 48 h. Treatment order (5 and 2 mg·kg of anhydrous caffeine or placebo) was randomly assigned to subjects using a single-blind, randomized, counterbalanced, crossover design. A 3 (treatment) × 2 (sets) ANOVA with repeated measures was used to detect differences in performance across treatment and time.
Compared with placebo, caffeine significantly (P < 0.05) enhanced peak knee flexion torque, knee extension/flexion total work, and knee extension/flexion power in bout 1 with no effect in bout 2. Only the 5-mg·kg dose of caffeine improved performance, with the magnitude of performance improvement ranging from 5% to 8%.
Data suggest that a relatively high (5-mg·kg body weight) but not low (2-mg·kg body weight) caffeine dose is ergogenic for maximal knee extension/flexion exercise.
Caffeine is the most widely used drug in the world, commonly ingested in coffee, tea, soda, and energy drinks. Its ability to enhance muscular work has been apparent since the early 1900s. Caffeine typically increases endurance performance; however, efficacy of caffeine ingestion for short-term high-intensity exercise is equivocal, which may be explained by discrepancies in exercise protocols, dosing, and subjects' training status and habitual caffeine intake found across studies. The primary aim of this review is to critically examine studies that have tested caffeine's ability to augment performance during exercise dependent on nonoxidative metabolism such as sprinting, team sports, and resistance training. A review of the literature revealed 29 studies that measured alterations in short-term performance after caffeine ingestion. Each study was critically analyzed using the Physiotherapy Evidence Database (PEDro) scale. The mean PEDro score was 7.76 +/- 0.87. Eleven of 17 studies revealed significant improvements in team sports exercise and power-based sports with caffeine ingestion, yet these effects were more common in elite athletes who do not regularly ingest caffeine. Six of 11 studies revealed significant benefits of caffeine for resistance training. Some studies show decreased performance with caffeine ingestion when repeated bouts are completed. The exact mechanism explaining the ergogenic effect of caffeine for short-term exercise is unknown.
The purpose of the present study was to examine the acute effects of a caffeine-containing supplement (SUPP) on 1 repetition maximum (1RM) bench press and leg extension strength, as well as time to exhaustion (TTE), during cycle ergometry at a power output that corresponded to 80% of VO2peak. The study used a double-blinded, placebo-controlled, crossover design. Twenty-one untrained men (mean +/- SD age = 23.0 +/- 2.6 yr) were randomly assigned to take either the SUPP or placebo (PLAC) first. The SUPP contained 400 mg of caffeine, 66.7 mg of capsicum extract, 10 mg of bioperine, and 40 mg of niacin, and the PLAC was microcrystalline cellulose. Sixty minutes after taking either the SUPP or PLAC, the subjects were tested for 1RM bench press and leg extension strength, as well as TTE. After 1 week of rest, the subjects ingested the opposite substance (SUPP or PLAC) and were retested for 1RM bench press and leg extension strength, as well as TTE. The results indicated that the SUPP had no effect on 1RM bench press strength, 1RM leg extension strength, or TTE at 80% VO2peak. These findings did not support the use of the caffeine-containing SUPP in the present study as an ergogenic aid in untrained individuals.
In an effort to assess the effects of caffeine ingestion on metabolism and performance during prolonged exercise, nine competitive cyclists (two females and seven males) exercised until exhaustion on a bicycle ergometer at 80% of Vo2 max. One trial was performed an hour after ingesting decaffeinated coffee (Trial D), while a second trial (C) required that each subject consume coffee containing 330 mg of caffeine 60 min before the exercise. Following the ingestion of caffeine (Trial C), the subjects were able to perform an average of 90.2 (SE +/- 7.2) min of cycling as compared to an average of 75.5 (SE +/- 5.1) min in the D Trial. Measurements of plasma free fatty acids, glycerol and respiratory exchange ratios evidenced a greater rate of lipid metabolism during the caffeine trial as compared to the decaffeinated exercise treatment. Calculations of carbohydrate (CHO) metabolism from respiratory exchange data revealed that the subjects oxidized roughly 240 g of CHO in both trials. Fat oxidation, however, was significantly higher (P less than 0.05) during the C Trial (118 g or 1.31 g/min) than in the D Trial (57 g or 0.75 g/min). On the average the participants rated (Perceived Exertion Scale) their effort during the C Trial to be significantly (P less than 0.05) easier than the demands of the D treatment. Thus, the enhanced endurance performance observed in the C Trial was likely the combined effects of caffeine on lipolysis and its positive influence on nerve impulse transmission.
The importance of carbohydrates as a fuel source during endurance exercise has been known for 60 years. With the advent of the muscle biopsy needle in the 1960s, it was determined that the major source of carbohydrate during exercise was the muscle glycogen stores. It was demonstrated that the capacity to exercise at intensities between 65 to 75% V̇O2max was related to the pre-exercise level of muscle glycogen, i.e. the greater the muscle glycogen stores, the longer the exercise time to exhaustion. Because of the paramount importance of muscle glycogen during prolonged, intense exercise, a considerable amount of research has been conducted in an attempt to design the best regimen to elevate the muscle’s glycogen stores prior to competition and to determine the most effective means of rapidly replenishing the muscle glycogen stores after exercise. The rate-limiting step in glycogen synthesis is the transfer of glucose from uridine diphosphate-glucose to an amylose chain. This reaction is catalysed by the enzyme glycogen synthase which can exist in a glucose-6-phosphate-dependent, inactive form (D-form) and a glucose-6-phosphate-independent, active form (I-form). The conversion of glycogen synthase from one form to the other is controlled by phosphorylation-dephosphorylation reactions.
The muscle glycogen concentration can vary greatly depending on training status, exercise routines and diet. The pattern of muscle glycogen resynthesis following exercise-induced depletion is biphasic. Following the cessation of exercise and with adequate carbohydrate consumption, muscle glycogen is rapidly resynthesised to near pre-exercise levels within 24 hours. Muscle glycogen then increases very gradually to above-normal levels over the next few days. Contributing to the rapid phase of glycogen resynthesis is an increase in the percentage of glycogen synthase I, an increase in the muscle cell membrane permeability to glucose, and an increase in the muscle’s sensitivity to insulin. The slow phase of glycogen synthesis appears to be under the control of an intermediate form of glycogen synthase that is highly sensitive to glucose-6-phosphate activation. Conversion of the enzyme to this intermediate form may be due to the muscle tissue being constantly exposed to an elevated plasma insulin concentration subsequent to several days of high carbohydrate consumption.
For optimal training performance, muscle glycogen stores must be replenished on a daily basis. For the average endurance athlete, a daily carbohydrate consumption of 500 to 600g is required. This results in a maximum glycogen storage of 80 to 100 µmol/g wet weight. To glycogen supercompensate in preparation for competition, the muscle glycogen stores must first be exercise-depleted. This should then be followed with a natural training taper. During the first 3 days of tapering, a mixed diet composed of 40 to 50% carbohydate should be consumed. During the last 3 days of tapering, a diet consisting of 70 to 80% carbohydrate is consumed. This procedure results in muscle glycogen concentrations that are comparable to those produced by more rigorous regimens that can result in chronic fatigue and injury. For rapid resynthesis of muscle glycogen stores, a carbohydrate supplement in excess of 1 g/kg bodyweight should be consumed immediately after competition or after a training bout. Continuation of supplementation every 2 hours will maintain a maximal rate of storage up to 6 hours after exercise. Supplements composed of glucose or glucose polymers are more effective for the replenishment of muscle glycogen stores after exercise than supplements composed of predominantly fructose. However, some fructose is recommended because it is more effective than glucose in the replenishment of liver glycogen.
The presence of a concentration of caffeine greater than or equal to 15 micrograms/ml in urine of athletes participating in competitive sport is a disqualifying factor. A study was conducted to establish how much caffeine needs to be ingested--in the form of coffee, tea or Coca-Cola--to approach or exceed this limit. Nine healthy volunteers participated in a randomised cross-over study and received caffeine in the form of these beverages, ingested within 15 minutes, in doses ranging from 1.52 mg/kg to 17.53 mg/kg. The latter dose is equivalent to nearly 8 cups of ordinary percolated coffee. The maximum caffeine concentration in urine recorded was 14 micrograms/ml, 3 hours after ingestion. A significant correlation was found between the caffeine dose and the maximum urinary concentration. The mean recovery of caffeine in urine was between 0.74% and 0.91% of the administered dose. The nature of the beverage did not appear to influence the degree of caffeine excretion. It is concluded that if a concentration of 15 micrograms caffeine/ml urine is recorded, it can safely be accepted that the athlete purposely ingested large amounts of the substance, in whatever form.
A series of four trials was carried out to investigate the effects of caffeine and coffee on the metabolic rate and substrate utilization in normal weight and obese individuals. In the first trial 8 mg/kg caffeine was compared with a placebo in normal weight subjects. Metabolic rate increased significantly during the 3 hr after caffeine ingestion. While plasma glucose, insulin, and carbohydrate oxidation did not change significantly, plasma free fatty acid levels rose from 432 +/- 31 to 848 +/- 135 muEq/liter and were accompanied by significant increases in fat oxidation during the last hour of the test. In the second and third trials the effects of coffee providing 4 mg/kg caffeine were studied in control and obese subjects. Metabolic rate increased significantly in both groups; however, significant increases in fat oxidation were only observed in the control group. Plasma free fatty acids did not change in the obese. In the fourth trial, coffee was taken with a 3080 kJ meal. The thermic effect of the meal was significantly greater after coffee than after decaffeinated coffee and again fat oxidation was significantly greater after coffee. In conclusion caffeine/coffee stimulates the metabolic rate in both control and obese individuals; however, this is accompanied by greater oxidation of fat in normal weight subjects.
Caffeine ingestion (3-9 mg/kg body weight) prior to exercise increases performance during prolonged endurance exercise and short-term intense exercise lasting approximately 5 min in the laboratory. These results are generally reported in well-trained elite or recreational subjects. However, there is a lack of well-controlled field studies to determine the applicability of laboratory results to the athletic world. Caffeine does not appear to enhance performance during incremental exercise tests lasting 8-20 min and during sprinting lasting less than 90 s, although research examining sprinting is rare. In addition, the mechanisms responsible for any improvement in endurance and short-term exercise have not been clearly established. The ergogenic effects of caffeine are present with urinary caffeine levels that are below the limit of 12 micrograms/ml allowed by the International Olympic Committee, which raises serious ethical issues regarding the use of caffeine to improve athletic performance. One solution would be to add caffeine to the list of banned substances, thereby requiring athletes to abstain from caffeine ingestion 48-72 hr prior to competition.
The purpose of this investigation was to determine the effect of caffeine ingestion on work output at various levels of perceived exertion during 30 min of isokinetic variable-resistance cycling exercise. Ten subjects completed six trials 1 hr after consuming either 6 mg.kg-1 caffeine (3 trials) or a placebo (3 trials). During each trial the subjects cycled at what they perceived to be a rating of 9 on the Borg rating of perceived exertion scale for the first 10 min, a rating of 12 for the next 10 min, and a rating of 15 for the final 10 min. Total work performed during the caffeine trials averaged 277.8 +/- 26.1 kJ, whereas the mean total work during the placebo trials was 246.7 +/- 21.5 kJ (p < .05). However, there were no significant differences between the conditions in respiratory exchange ratio. These data suggest that caffeine may play an ergogenic role in exercise performance by altering both neural perception of effort and substrate availability.
Caffeine is consumed in many beverages and foods throughout the world. It is the most commonly used drug in North America and, probably, in many other countries. The short term consumption of caffeine may result in increased urination, gastrointestinal distress, tremors, decreased sleep, and anxiety symptoms in certain individuals. The long term consumption of caffeine at < 5 cups/day does not appear to increase the risk of cancer, cardiovascular disease, peptic ulcer disease or cardiac arrhythmias.
At the cellular level, caffeine is a competitive antagonist of adenosine receptors and probably acts directly on the ryanodine receptor (Ca++ release channel) to potentiate Ca++ release from skeletal muscle sarcoplasmic reticulum. As a result of these 2 cellular mechanisms of action, caffeine causes increased lipolysis, a facilitation of central nervous system transmission, a reduction in plasma potassium during exercise, an increased force of muscle contraction at lower frequencies of stimulation, and a sparing of muscle glycogen (partially or wholly due to an increase in free fatty acid oxidation). These mechanisms of action would predict that caffeine should be of ergogenic benefit during endurance exercise performance, especially when glycogen depletion would be rate limiting to performance. A review of the literature suggests that caffeine at doses of approximately 6 mg/kg is not of ergogenic benefit to high intensity exercise performance, but similar doses are ergogenic in endurance exercise performance. These doses (approximately 6 mg/kg) would result in urinary caffeine concentrations less than the current International Olympic Committee restricted level of 12 mg/L, and consideration should be given to lowering this level.