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Caffeine ingestion, affect and perceived exertion during prolonged cycling
Abstract
Caffeine's metabolic and performance effects have been widely reported. However, caffeine's effects on affective states during prolonged exercise are unknown. Therefore, this was examined in the present study. Following an overnight fast and in a randomised, double-blind, counterbalanced design, twelve endurance trained male cyclists performed 90 min of exercise at 70% VO(₂ max) 1h after ingesting 6 mg kg⁻¹ BM of caffeine (CAF) or placebo (PLA). Dimensions of affect and perceived exertion were assessed at regular intervals. During exercise, pleasure ratings were better maintained (F(₃,₃₈)=4.99, P < 0.05) in the CAF trial compared to the PLA trial with significantly higher ratings at 15, 30 and 75 min (all P < 0.05). Perceived exertion increased (F(₃,₃₈) = 19.86, P < 0.01) throughout exercise and values, overall, were significantly lower (F(₁,₁₁) = 9.26, P < 0.05) in the CAF trial compared to the PLA trial. Perceived arousal was elevated during exercise but did not differ between trials. Overall, the results suggest that a moderate dose of CAF ingested 1h prior to exercise maintains a more positive subjective experience during prolonged cycling. This observation may partially explain caffeine's ergogenic effects.
... Participants were brought to the laboratory on two separate days for testing. The testing days were separated by at least one week and participants were instructed to refrain from exercise within twenty-four hours of testing times to avoid possible impacts on testing day performance [23,[31][32][33]. All participants were instructed to wear comfortable running attire and the same self-provided shoes for both testing days. ...
... https://doi.org/10.1371/journal.pone.0270335.g001 differences in performance due to dietary supplements [31,[33][34][35][36]. Of these studies, three specifically involved exercise to exhaustion [34][35][36] and the largest sample size was twelve [34]. ...
... As shown in Table 2, the average time to exhaustion in this population of recreational runners was under 10 minutes, with six participants reaching volitional exhaustion in less than seven minutes. Studies with similar research objectives across multiple testing days [31,33] utilized protocols that had participants exercise at a constant pace for an extended period which led to significant differences between the testing days. This further illustrates the potential limitation that a lower-intensity constant-pace run could lead to a larger difference observed between the two testing days. ...
Breathing plays a vital role in everyday life, and specifically during exercise it provides working muscles with the oxygen necessary for optimal performance. Respiratory inductance plethysmography (RIP) monitors breathing through elastic belts around the chest and abdomen, with efficient breathing defined by synchronous chest and abdomen movement. This study examined if providing runners with visual feedback through RIP could increase breathing efficiency and thereby time to exhaustion. Thirteen recreational runners (8F, 5M) ran to exhaustion on an inclined treadmill on two days, with visual feedback provided on one randomly chosen day. Phase angle was calculated as a measure of thoraco-abdominal coordination. Time to exhaustion was not significantly increased when visual feedback was provided (p = 1). Phase angle was not significantly predicted by visual feedback (p = 0.667). Six participants improved phase angle when visual feedback was provided, four of whom increased time to exhaustion. Four participants improved phase angle by 9° or more, three of whom increased time to exhaustion. Participants who improved phase angle with visual feedback highlight that improving phase angle could increase time to exhaustion. Greater familiarization with breathing techniques and visual feedback and a different paradigm to induce running fatigue are needed to support future studies of breathing in runners.
... One of the most widely consumed bioactive compounds naturally present in foods and beverages and that has analgesic potential is caffeine (1,3,7-trimethylxanthine) (10). Many studies have demonstrated that the ingestion of caffeine reduces both muscle pain (11)(12)(13)(14) and perceived exertion (14,15) during physical exercise in healthy individuals. These findings suggest that the ingestion of caffeine before a bout of exercise might be a promising candidate to alleviate the exacerbated sensations of pain and exertion during exercise in FM patients. ...
... It should be pointed out that isometric handgrip tasks are of limited functional relevance and not commonly used as part of an exercise training program to treat FM patients (9). Moreover, studies that observed an effect of caffeine ingestion on perceived muscle pain and perceived exertion during exercise in healthy individuals used higher doses of caffeine (i.e., ≥ 5 mg of caffeine per kg of body mass) (11)(12)(13)(14)(15)) and a whole-body exercise model (e.g., cycling) that involves the recruitment of large muscle groups. Thus, whether caffeine reduces muscle pain and effort sensations during a whole-body exercise in FM patients is still unknown. ...
... The perceived exertion progressively increased during exercise, but values were ∼8% lower when the FM patients ingested caffeine before exercise. Many studies have documented an effect of caffeine intake on the reduction in perceived exertion during constant-load cycling, but these studies were performed in healthy individuals and at higher exercise intensities than that used in the present study (14,15). Interestingly, the magnitude of reduction in perceived exertion observed in the present study was similar to that summarized in a meta-analysis (30), in which a reduction of 6% was reported in perceived exertion during exercise after caffeine intake, in comparison with the placebo. ...
Objective
Exacerbated perceived exertion and muscle pain responses during exercise might limit physical activity practice in fibromyalgia patients. Thus, nutritional strategies that can reduce perceived exertion and muscle pain during exercise in fibromyalgia patients would be useful. The purpose of this study was to investigate the effects of acute caffeine intake on the perceptions of exertion and muscle pain during a moderate intensity exercise in women with fibromyalgia.Method: Using a randomized, double-blinded, placebo-controlled and crossover experimental design, eleven sedentary women diagnosed with fibromyalgia (age: 44.6 ± 10.5 years; body mass index: 28.5 ± 4.5 kg.m⁻²) ingested a capsule containing either caffeine (5 mg per kg of body mass) or cellulose (placebo), 60 minutes before performing a 30-minute constant-load cycling exercise, with work rate fixed at 50% of their individual peak workload attained in an incremental exercise test. Ratings of perceived leg muscle pain and perceived exertion were assessed every 5 minutes of exercise.Results: The perceived leg muscle pain was similar (F(1,10) = 1.18, p = 0.30, ŋ² = 0.11) between caffeine (2.1 ± 1.2 arbitrary units) and placebo conditions (2.2 ± 0.9 arbitrary units). The perceived exertion, however, was on average 8 ± 6% lower (F(1,10) = 12.13; p = 0.006; ŋ² = 0.55) during exercise in the caffeine condition (12.4 ± 1.3 arbitrary units) than in the placebo condition (13.1 ± 1.1 arbitrary units).Conclusions: These findings indicate that acute caffeine intake could be an attractive strategy to attenuate the exacerbated perceived exertion of fibromyalgia patients during moderate intensity exercise.
... Caffeine is one of the most widely used supplements in the world. It is well founded that caffeine is an ergogenic resource (i.e., a resource to enhance physical performance) for endurance exercise [1][2][3][4], but its effect for resistance training performance seem to be unclear [5], depending on the factors as muscle group involved and the regular caffeine ingestion habits [5,6]. ...
... Caffeine and concurrent training VOL. 6 (2) Despite caffeine supplementation improve of physical performance in aerobic and anaerobic exercise, when done isolated [3,[13][14][15], no studies have examined the combination of aerobic and RES in an acute exercise bout with caffeine supplementation. Therefore, the aim of this study was to examine the influence of caffeine supplementation on lower body resistance-training performance when this exercise method was preceded with and without an acute endurance bout of exercise. ...
... Caffeine and concurrent training VOL. 6 (2) There is evidence that aerobic exercise performed prior to resistance exercises may have detrimental effects, such as impairment of acute RES performance on the second [20,21]. A metabolic hypothesis has been suggested to explain the decline of physical performance during resistance training preceded by aerobic training [20,22]. ...
The aim of this study was to examine the influence of caffeine supplementation (4.5 mg ⋅ kg−1) on lower body resistance training performance preceded with and without an acute bout of endurance exercise. In a double-blinded crossover study, 10 moderately active males (20.6±2.1 yo) carried out six exercise sessions (2 x 1RM sessions; 2 x resistance sessions; 2 concurrent sessions). Resistance exercise sessions (RES+CAF and RES+PLA) were carried out with 4 maximum sets of leg press, leg extension and leg curl to volitional fatigue at 65% of 1RM for each exercise with 1 min inter-set and inter-session rest interval. Sessions consisted on 4 maximum sets to volitional fatigue at 65% of 1RM for each exercise with 1 min of rest interval between sets and exercises. Concurrent training sessions (CON+CAF and CON+PLA) were identical but were preceded by 30 min of continuous treadmill running at 75-85% HRmax. Physical performance showed a significant main effect for treatment (p < 0.0001), protocol (p < 0.02), exercises (p < 0.0001) and sets (p < 0.0001). Physical performance during RES was reduced after endurance exercise, indicating a cumulative effect of CON. Caffeine supplementation blunted this cumulative effect. We conclude that caffeine supplementation could be used to improve the resistance-training performance when it is done immediately after an aerobic training.
... Caffeine is classified as part of the methylxanthine family of drugs (Cechella et al., 2014;Mohr, Nielsen, Bangsbo, 2011) and is extensively consumed by athletes as an ergogenic aid (Backhouse et al., 2011;Mohr, Nielsen, Bangsbo, 2011) since its removal from the World Anti-Doping Agency (WADA) prohibited list of substances (Backhouse et al., 2011;Mohr, Nielsen, Bangsbo, 2011). According to the Medical Council of International Olympic Committee (IOC), caffeine is allowed in sports as long as its urinary excretion level is below 12 µg/mL (Bell, Jacobs, Ellerington, 2001). ...
... Caffeine is classified as part of the methylxanthine family of drugs (Cechella et al., 2014;Mohr, Nielsen, Bangsbo, 2011) and is extensively consumed by athletes as an ergogenic aid (Backhouse et al., 2011;Mohr, Nielsen, Bangsbo, 2011) since its removal from the World Anti-Doping Agency (WADA) prohibited list of substances (Backhouse et al., 2011;Mohr, Nielsen, Bangsbo, 2011). According to the Medical Council of International Olympic Committee (IOC), caffeine is allowed in sports as long as its urinary excretion level is below 12 µg/mL (Bell, Jacobs, Ellerington, 2001). ...
... The current study examined the effect of different doses of caffeine on performance, rating of perceived exertion, and pain perception in female teenager athletes of karate. The results showed that consumption of 5 mg/kg caffeine compared with placebo reduced RPE and perceptions of pain after muscular endurance test, which is in agreement with a range of preceding studies (Backhouse et al., 2011;Doherty, Smith, 2005;Duncan et al., 2013) and is contrast to studies reporting no significant reductions of RPE and perceptions of pain after tests following acute caffeine ingestion (Astorino et al., 2011b;Astorino, Roupoli, Valdivieso, 2012). ...
The present study set to examine the effects of different doses of caffeine on performance, rating of perceived exertion (RPE), and pain perception in female teenager athletes of karate. Ten female karate athletes (16.8±1.23 years; height 1.59±0.28 m; body-mass 57.73±8.33 kg; BMI 22.71±3.05 kg/m2) participated in the study. A double-blind, randomized, and crossover counterbalanced design was used. In three sessions (with an interval of seven days'), ten female karate athletes ingested low dose (2 mg/kg), moderate dose (5 mg/kg) caffeine, and placebo. Sixty minutes after consumption, they performed the tests as below: one repetition maximum and 60% of one repetition maximum in the leg press, explosive power test, and anaerobic RAST test. After the tests, the participants’ RPE (6–20 scale) and pain perception (0–10 scale) were recorded using various categorical scales. The results showed that caffeine ingestion at moderate dose significantly reduced RPE and pain perception values compared with the placebo during muscular endurance test (P=0.0001 and P=0.039, respectively). The findings suggest that caffeine dose of 5 mg/kg body mass appears to improve RPE and pain perception in female teenager athletes of karate. The dose of 2 mg/kg body mass does not confer any additional improvement in performance.
... However, these studies were conducted in resting subjects and to our knowledge, only one study has directly examined alterations in mood with caffeine intake during exercise. Backhouse et al. [11] required male cyclists to exercise for 1.5 h at 70% VO 2 max after ingestion of caffeine (6 mg/kg) or placebo. Continuously during exercise, RPE was assessed using the Borg [12] 6-20 scale, and affect was measured using the Feeling Scale [13] and Felt Arousal scale [14], as feelings of pleasure or displeasure as well as arousal may alter willingness to continue exercise which may modify overall performance for athletes and adherence for recreational exercisers. ...
... Caffeine has been reported to improve mood and cognitive performance [9,10] in resting individuals, yet only one study [11] examined caffeine-mediated changes in perceptual responses during exercise, although performance was not measured. In the current study, RPE, pain, and affect were measured during a simulated cycling time trial after ingestion of 5 mg/kg caffeine or placebo. ...
... FS values are lower than previously reported [11], which may be due to the greater intensity induced in this study via the simulated time trial. A dose response relationship is revealed between intensity and affect [28], in that workloads below the lactate (ventilatory) threshold do not negatively impact affect, yet at higher intensities, affect is typically reduced. ...
Caffeine has been reported to alter perceptions of exertion, muscle pain, and mood, yet the majority of existing data were obtained in resting volunteers or during steady-state exercise. The primary aim of this study was to examine the effects of caffeine on rating of perceived exertion (RPE) and perceptions of leg pain, arousal, and pleasure/displeasure during a simulated cycling time trial. Endurance-trained (n=8, VO(2)max=57.5±3.9 mL/kg/min) and active (n=8, VO(2)max=46.5±6.3 mL/kg/min) men initially completed two familiarization trials separated by at least 48 h. Over the next three trials, they completed a 10 km time trial preceded by ingestion of drinks containing caffeine (5 mg/kg ingested on 2 separate days) or placebo. Treatments were ingested using a single-blind, crossover design, and participants were deceived as to the content of all drinks. During exercise, RPE (6-20 scale), leg pain (0-10 scale), arousal (Felt Arousal Scale), and pleasure/displeasure (Feeling Scale) were recorded using various categorical scales. Repeated measures analysis of variance was used to assess differences in all variables across time and treatments, with fitness level used as a between-subjects variable. Pleasure/displeasure was altered (p<0.05, partial eta-squared (η(2))=0.23) with caffeine compared to placebo, although leg pain, RPE, and arousal were similar (p>0.05) across treatments. Caffeine increased (p<0.05, η(2)=0.27) cycling performance by 0.3-2.0% versus placebo, with no effect (p>0.05) of fitness level. Only in trained men; however, was there a significant caffeine-mediated improvement in cycling performance, which was consequent with diminished mood in trained and improved mood in active individuals.
... Furthermore, the motor task-specific homeostatic regulatory processes related to exercise intensity play an important role for the determinants of perceived fatigue (e.g., effort perception, exercise-induced pain/discomfort, affective valence) [5]. The modulation of the regulatory processes within the involved subsystems (e.g., central nervous system and muscle), for instance, by supplements such as caffeine or dietary nitrate, has been shown to have a positive effect on the various perceptions during exercise (e.g., effort and exerciseinduced pain) [51,109]. In addition, the presence of external stimuli (e.g., verbal motivation, monetary incentives, feedback on performance, auditory and visual stimuli) as well as internal stimuli (e.g., self-talk, intermediate goal setting, visualization strategies) may influence the interpretation of sensory signals and thus the extent of perceived motor fatigue [48,49,110]. ...
... For instance, neuromodulation techniques like tDCS are suitable to alter cortical excitability and to investigate the effects of changed neural properties on motor performance fatigue and perceived motor fatigue [67]. Furthermore, other interventions can be applied to modify neural as well as muscular properties (e.g., triggering 'mental fatigue' by a sustained cognitive task, supplements like caffeine or dietary nitrate, ischemic preconditioning) to investigate their effects on the different dimensions of motor task-induced state fatigue [18,51,52,109]. Interventions aiming to modulate the psychological determinants of endurance performance have also been shown to induce changes in motor performance and the perceptual responses to fatiguing exercise [48]. These strategies could be used to investigate the role of cognitive processes in the interpretation of perceptual responses and the change in affective valence emerging during fatiguing motor exercise. ...
Fatigue has been defined differently in the literature depending on the field of research. The inconsistent use of the term fatigue complicated scientific communication, thereby limiting progress towards a more in-depth understanding of the phenomenon. Therefore, Enoka and Duchateau (Med Sci Sports Exerc 48:2228–38, 2016, [3]) proposed a fatigue framework that distinguishes between trait fatigue (i.e., fatigue experienced by an individual over a longer period of time) and motor or cognitive task-induced state fatigue (i.e., self-reported disabling symptom derived from the two interdependent attributes performance fatigability and perceived fatigability). Thereby, performance fatigability describes a decrease in an objective performance measure, while perceived fatigability refers to the sensations that regulate the integrity of the performer. Although this framework served as a good starting point to unravel the psychophysiology of fatigue, several important aspects were not included and the interdependence of the mechanisms driving performance fatigability and perceived fatigability were not comprehensively discussed. Therefore, the present narrative review aimed to (1) update the fatigue framework suggested by Enoka and Duchateau (Med Sci Sports Exerc 48:2228–38, 2016, [3]) pertaining the taxonomy (i.e., cognitive performance fatigue and perceived cognitive fatigue were added) and important determinants that were not considered previously (e.g., effort perception, affective valence, self-regulation), (2) discuss the mechanisms underlying performance fatigue and perceived fatigue in response to motor and cognitive tasks as well as their interdependence, and (3) provide recommendations for future research on these interactions. We propose to define motor or cognitive task-induced state fatigue as a psychophysiological condition characterized by a decrease in motor or cognitive performance (i.e., motor or cognitive performance fatigue, respectively) and/or an increased perception of fatigue (i.e., perceived motor or cognitive fatigue). These dimensions are interdependent, hinge on different determinants, and depend on body homeostasis (e.g., wakefulness, core temperature) as well as several modulating factors (e.g., age, sex, diseases, characteristics of the motor or cognitive task). Consequently, there is no single factor primarily determining performance fatigue and perceived fatigue in response to motor or cognitive tasks. Instead, the relative weight of each determinant and their interaction are modulated by several factors.
... Although feelings of pleasure/displeasure and level of arousal are key factors in athletic performance (Astorino, Cottrell, et al., 2012), these measures are reported in only a limited number of exercise studies to date. Moderate doses of caffeine (3.7-6 mg • kg −1 ) enhanced feelings of pleasure in trained males during endurance cycling (Backhouse, Biddle, Bishop, & Williams, 2011), high-intensity cycling (Astorino, Cottrell, et al., 2012) and simulated soccer activity (Gant, Ali, & Foskett, 2010), yet failed to affect changes in arousal. No comparable data has been published for female athletes. ...
... This is the first study addressing the influence of caffeine on these parameters in females and therefore female athletes. Comparable studies in males have consistently shown that caffeine ingestion significantly increases feelings of pleasure during exercise (Astorino, Cottrell, et al., 2012;Backhouse et al., 2011;Gant et al., 2010) yet does not affect arousal. Combined with the current data, these studies suggest that caffeine influences feelings of pleasure and arousal in a sex-dependent manner. ...
We examined the influence of caffeine supplementation on cognitive performance and perceptual responses in female team-game players taking low-dose monophasic oral contraceptives of the same hormonal composition. Ten females (24 ± 4 years; 59.7 ± 3.5 kg body mass; 2-6 training sessions per week) took part in a randomised, double-blind, placebo-controlled crossover-design trial. A 90-min intermittent treadmill-running protocol was completed 60 min following ingestion of a capsule containing either 6 mg • kg(-1) anhydrous caffeine or artificial sweetener (placebo). Perceptual responses (ratings of perceived exertion (RPE), feeling scale (FS), felt arousal scale (FAS)), mood (profile of mood states (POMS)) and cognitive performance (Stroop test, choice reaction time (CRT)) were completed before, during and after the exercise protocol, as well as after ~12 h post exercise. Caffeine ingestion significantly enhanced the ratings of pleasure (P = 0.008) and arousal (P = 0.002) during the exercise protocol, as well as increased vigour (POMS; P = 0.007), while there was a tendency for reduced fatigue (POMS; P = 0.068). Caffeine ingestion showed a tendency to decrease RPE (P = 0.068) and improve reaction times in the Stroop (P = 0.072) and CRT (P = 0.087) tests. Caffeine supplementation showed a positive effect on perceptual parameters by increasing vigour and a tendency to decrease fatigue during intermittent running activity in female games players taking low-dose monophasic oral contraceptive steroids (OCS).
... Training data also included women exercising in follicular and luteal phases (Janse De Jonge et al. 2012;Pivarnik et al. 1992). Experiments that involved supplementations (e.g., caffeine ingestion and carbohydrate replacement) were excluded as they have been shown to affect the RPE response (Backhouse et al. 2011;Carter et al. 2005;Casal and Leon 1985;Doherty and Smith 2005;Kang et al. 1996;Utter et al. 1997Utter et al. , 1999. The training data utilized subjects who were healthy and active but not endurance trained. ...
... The training datasets used for the RPE prediction minimized secondary effects that can significantly alter RPE response such as head cooling, caffeine ingestion, antecedent fatiguing exercise, and pre-exercise mental fatigue occur (Ansley et al. 2008;Backhouse et al. 2011;Casal and Leon 1985;Doherty and Smith 2005;Eston et al. 2007;Marcora et al. 2009;Mündel et al. 2007). Therefore, the RPE prediction may not be accurate when these effects are introduced. ...
Rating of perceived exertion (RPE) is a scale of exercise difficulty and has been hypothesized to be a regulator of work rate during self-pacing. The goal of this work was to develop a dynamic prediction of RPE and to characterize the control strategy employed to reduce work rate during self-paced exercise using RPE as feedback.
Training and test data were acquired from the literature to develop a linear regression of RPE as a function of four physiological variables: core temperature, mean-weighted skin temperature, metabolic rate, and integral of relative oxygen consumption (R (2) = 0.85). A thermoregulatory model was used to predict core and mean-weighted skin temperature. Utilizing self-paced cycling and running data from the literature, we characterized reductions in work rate with a proportional-derivative control algorithm with RPE as feedback.
Bland-Altman analysis revealed the necessity to parameterize RPE equations for untrained and endurance-trained individuals. Afterwards, dynamic predictions of RPE were accurate for a wide range of activity levels and air temperatures for walking, running, and cycling (LoA and bias of 2.3 and -0.03, respectively). For self-paced exercise, the control algorithm characterized the trend and magnitude of work rate reductions for cycling and running, and showed regulated RPE to be less conservative for shorter vs. longer duration exercise.
A novel methodology to characterize self-paced work intensity, based upon dynamic physiologic response, is provided. The complete model is a useful tool that estimates performance decrements during self-paced exercise and predicts tolerance time for exhaustive fixed-rate exercise.
... Both caffeine (Desbrow et al. 2009;Irwin et al. 2011;Lane et al. 2013a) and nitrate (NO 3 -) (Cermak et al. 2012a;Lansley et al. 2011a;Vanhatalo et al. 2011) have been shown to improve simulated road cycling performance in a variety of protocols. Through mechanisms likely related to the central ner-vous system (CNS) (Costill et al. 1978;Tarnopolsky 2008), caffeine has been shown to improve arousal states (Backhouse et al. 2011) and reduce perceived exertion during steady-state exercise (Backhouse et al. 2011;Doherty and Smith 2005;Lane et al. 2013a), resulting in enhanced performance during sustained high-intensity cycling events Lane et al. 2013a;McNaughton et al. 2008). Contemporary protocols for caffeine use are based on evidence that moderate intakes (3 mg·kg −1 ) of caffeine are equally as effective as larger doses (6 mg·kg −1 ) (Desbrow et al. 2012) for eliciting these CNS effects, and that caffeinated gums can also provide a rapidly absorbed caffeine dose (Kamimori et al. 2002;Ryan et al. 2013). ...
... Both caffeine (Desbrow et al. 2009;Irwin et al. 2011;Lane et al. 2013a) and nitrate (NO 3 -) (Cermak et al. 2012a;Lansley et al. 2011a;Vanhatalo et al. 2011) have been shown to improve simulated road cycling performance in a variety of protocols. Through mechanisms likely related to the central ner-vous system (CNS) (Costill et al. 1978;Tarnopolsky 2008), caffeine has been shown to improve arousal states (Backhouse et al. 2011) and reduce perceived exertion during steady-state exercise (Backhouse et al. 2011;Doherty and Smith 2005;Lane et al. 2013a), resulting in enhanced performance during sustained high-intensity cycling events Lane et al. 2013a;McNaughton et al. 2008). Contemporary protocols for caffeine use are based on evidence that moderate intakes (3 mg·kg −1 ) of caffeine are equally as effective as larger doses (6 mg·kg −1 ) (Desbrow et al. 2012) for eliciting these CNS effects, and that caffeinated gums can also provide a rapidly absorbed caffeine dose (Kamimori et al. 2002;Ryan et al. 2013). ...
Both caffeine and beetroot juice have ergogenic effects on endurance cycling performance. We investigated whether there is an additive effect of these supplements on the performance of a cycling time trial (TT) simulating the 2012 London Olympic Games course. Twelve male and 12 female competitive cyclists each completed 4 experimental trials in a double-blind Latin square design. Trials were undertaken with a caffeinated gum (CAFF) (3 mg·kg(-1) body mass (BM), 40 min prior to the TT), concentrated beetroot juice supplementation (BJ) (8.4 mmol of nitrate (NO3(-)), 2 h prior to the TT), caffeine plus beetroot juice (CAFF+BJ), or a control (CONT). Subjects completed the TT (females: 29.35 km; males: 43.83 km) on a laboratory cycle ergometer under conditions of best practice nutrition: following a carbohydrate-rich pre-event meal, with the ingestion of a carbohydrate-electrolyte drink and regular oral carbohydrate contact during the TT. Compared with CONT, power output was significantly enhanced after CAFF+BJ and CAFF (3.0% and 3.9%, respectively, p < 0.01). There was no effect of BJ supplementation when used alone (-0.4%, p = 0.6 compared with CONT) or when combined with caffeine (-0.9%, p = 0.4 compared with CAFF). We conclude that caffeine (3 mg·kg(-1) BM) administered in the form of a caffeinated gum increased cycling TT performance lasting ∼50-60 min by ∼3%-4% in both males and females. Beetroot juice supplementation was not ergogenic under the conditions of this study.
... Of these mechanisms, it is the competitive inhibition of adenosine receptors and subsequent central nervous system stimulation that provides the most significant basis for improved exercise performance [152][153][154]. This mechanism may explain the reported suppressed feelings of discomfort and pain experienced [158,165,176] and the attenuated ratings of perceived exertion (RPE) [156,163] during exercise with pre-exercise caffeine consumption. ...
... Caffeine has a half-life of 4-6 h and peak serum caffeine levels typically occur 1-2 h after ingestion [177]. Therefore, many studies investigating the effects of caffeine on endurance performance administer caffeine 1 h prior to exercise to correspond with peak serum values [159,161,176]. This seems logical; however, the relative importance of serum caffeine levels to performance may depend on the degree of habituation of caffeine use. ...
Endurance athletes rarely compete in the fasted state, as this may compromise fuel stores. Thus, the timing and composition of the pre-exercise meal is a significant consideration for optimizing metabolism and subsequent endurance performance. Carbohydrate feedings prior to endurance exercise are common and have generally been shown to enhance performance, despite increasing insulin levels and reducing fat oxidation. These metabolic effects may be attenuated by consuming low glycemic index carbohydrates and/or modified starches before exercise. High fat meals seem to have beneficial metabolic effects (e.g., increasing fat oxidation and possibly sparing muscle glycogen). However, these effects do not necessarily translate into enhanced performance. Relatively little research has examined the effects of a pre-exercise high protein meal on subsequent performance, but there is some evidence to suggest enhanced pre-exercise glycogen synthesis and benefits to metabolism during exercise. Finally, various supplements (i.e., caffeine and beetroot juice) also warrant possible inclusion into pre-race nutrition for endurance athletes. Ultimately, further research is needed to optimize pre-exercise nutritional strategies for endurance performance.
... As stated, high-arousal products also help individuals face threats to their self-identity to restore their self-worth [53]. For example, proper intake of caffeine (coffee, tea, energy drinks, or soda) can restore vitality, improve concentration, creativity, and problem-solving skills [56]. ...
Start temporal landmark is the beginning of a period of time. Previous research has established that individuals have the need for arousal at the start temporal landmarks but less research has focused on individual differences and the relationship between self and others (independent vs. interdependent). This research examines the influence of individuals’ self-construal on the relationship between start temporal landmarks and arousal product preference. Three experiments with 1136 participants were recruited from a university, community, and online store in Southern China. The data were analyzed by Cochran–Mantel–Haenszel on SPSS 26.0 software program. The results showed that self-construal influenced the effect of start temporal landmarks on arousal product preference. Specifically, compared with ordinary temporal landmarks, individuals with interdependent self-construal prefer high arousal products under start temporal landmarks, whereas those with independent self-construal show no significantly different preference for high or low arousal products under the start temporal landmarks. Furthermore, psychological resources play a mediating role. This research extends the theoretical research on self-construal in the field of temporal landmarks and arousal. It also has important practical implications for improving the sales of high arousal products.
... Thus, dopamine becomes less inhibited, increasing the dopamine concentrations during exercise. Another ergogenic mechanism of caffeine is to decrease the expression of tryptophan hydroxylase (TPH); the degradation of tryptophan modulates the amount of serotonin that crosses the blood-brain barrier 37 . A lower serotonin/dopamine ratio reduces central fatigue and improves performance 38 . ...
Over the years, the search for nutritional strategies that promote improved sports performance has increased. Among the available options, energy drinks appear as potential nutritional resources for this purpose, because they offer, in addition to caffeine, substances that act synergistically to improve performance, such as taurine, carbohydrates, amino acids, vitamins and minerals, promoting improved performance for both amateur and professional athletes. The aim of the study was to verify the effects of ingesting energy drinks with (ED1) and without carbohydrates (ED0) containing 2 mg·kg-1 of caffeine, and a decaffeinated placebo (PL) on cardiovascular, metabolic and performance parameters during cycling. Twelve male cyclists (age = 24.4 ± 6.6 years old) volunteered to participate in this study. The protocol consisted of three experimental sessions of 60 min of continuous cycling (65-75% of VO 2maxE) followed by time-trial 6 km. The subjects ingested ED1, ED0 or a placebo drink (PL) 40 min before beginning the exercise. The heart rate (HR), blood pressure (BP), plasma glucose and lactate concentrations , and the time taken to complete the 6 km time-trial were evaluated. The time taken to complete the time-trial was significantly higher (p < 0.05) in the PL group than in the groups ED1 and ED0. This time significantly decreased after the ED1 consumption relative to that for the ED0 consumption. Heart rate, systolic and diastolic arterial pressure and in the plasma glucose and lactate concentrations were similar in all the considered groups. These results demonstrate that ED1 consumption appears to be more effective at maximizing performance during the last 6 km. Resumen Con el paso de los años, se ha incrementado la búsqueda de estrategias nutricionales que promuevan un mejor rendimiento deportivo. Entre las opciones disponibles, las bebidas energéticas aparecen como potenciales recursos nutricionales para este fin, pues ofrecen, además de la cafeína, sustancias que actúan sinérgicamente para mejorar el rendimiento, como taurina, carbohidratos, aminoácidos, vitaminas y minerales, promoviendo un mejor rendimiento para atletas tanto aficionados como profesionales. El objetivo del estudio fue verificar los efectos de la ingestión de bebidas energéticas con (ED1) y sin carbohidratos (ED0) que contienen 2 mg · kg-1 de cafeína y un placebo descafeinado (PL) sobre los parámetros cardiovasculares, metabólicos y de rendimiento durante el ciclismo. Doce ciclistas varones (edad = 24,4 ± 6,6 años) participaron voluntariamente en este estudio. El protocolo consistió en tres sesiones experimentales de 60 min de ciclismo continuo (65-75% del VO 2max) seguidas de una prueba contrarreloj de 6 km. Los sujetos ingirieron ED1, ED0 o una bebida placebo (PL) 40 minutos antes de comenzar el ejercicio. Se registró la frecuencia cardíaca (FC), la presión arterial (PA), las concentraciones plasmáticas de glucosa y lactato y el tiempo necesario para completar la prueba contrarreloj de 6 km. El tiempo necesario para completar la contrarreloj en el grupo PL fue significativamente mayor (p <0,05) que en los grupos ED1 y ED0. Este tiempo disminuyó significativamente después del consumo de ED1 en relación con el consumo de ED0. La frecuencia cardíaca, la presión arterial sistólica y diastólica y las concentraciones plasmáticas de glucosa y lactato fueron similares en todos los grupos. Estos resultados demuestran que el consumo de ED1 parece ser más eficaz para maximizar el rendimiento durante los últimos 6 km. Palabras clave: Cafeína. Taurina. Bebidas deportivas. Rendimiento deportivo. Ciclismo
... 8 The intake of caffeine leads to later exhaustion and has a positive influence on the subjective evaluation of the effort. The increase in mood, alertness, and attention during training contributes to enhanced performance, 9 as well as a supposedly reduced perception of pain. 10 Caffeine also shows an influence on psychological factors, such as anxiety or anxiety disorders. A review of eight included studies was able to demonstrate a positive correlation between anxiety and/or panic disorders and caffeine. ...
Caffeine’s influence on numerous physical functions indicates that it has more than a simple stimulating effect. The aim of this study is to investigate the effects of caffeine on well-being, taking into
account physical activity, anxiety, and depression as mediators.
A sample of 160 subjects 50 years of age and older were recruited for this study. Five standardized questionnaires and an extension of the simple mediatized regression with three mediators made it possible to check the model relationships.
The results could demonstrate no indirect effect through one or a combination of the mediator variables, but a direct effect of caffeine on well-being ( p = 0.01, b = 0.16), provided that the three variables
were taken into account.
... Koffein wirkt primär im zentralen Nervensystem und diätetisches Nitrat moduliert hauptsächlich Regulationsprozesse auf Muskelebene. Beide sind jedoch in der Lage, die Leistungsfähigkeit bei submaximalen anhaltenden motorischen Aufgaben zu verbessern und die Anstrengungswahrnehmung sowie die belastungsinduzierte Schmerzwahrnehmung bei gesunden Menschen zu reduzieren [8,46,64]. Chronische Interventionen hingegen umfassen die repetitive Applikation von Maßnahmen. Dazu gehören z. ...
"Fatigue"has been defined differently depending on the field of research (e.g., neurology, psychology, exercise physiology), which has led to an inconsistent use of the term, limiting scientific progress. Therefore, this article proposes a taxonomy that promotes a better understanding of fatigue in people with multiple sclerosis (pwMS), allowing a clear characterization of the phenomenon and the application of effective interventions. First, a distinction should be made between trait and state fatigue. Trait fatigue describes the fatigue experienced by an individual over a longer period of time, e.g. weeks and months. State fatigue, on the other hand, describes the acute and temporary change in motor and/or cognitive performance, as well as various perceptual qualities that emerge in the context of a defined sustained motor and/or cognitive task. State fatigue, induced by sustained physical activity, can be defined as a disabling psychophysiological symptom characterized by a decrease in motor performance (motor performance fatigability) and/or an increased perception of fatigue (perceived fatigability). These two dimensions are interdependent, not separable, and should be quantified simultaneously. The magnitude of exercise-induced state fatigue depends on the rates of change in motor performance fatigability as well as perceived fatigability and is thus normalized to the demands of the motor task. Motor performance fatigability is determined by neural (muscle activation) and muscular (contractile function) factors, whereas perceived fatigability depends on the psychological status of the individual as well as the body's homeostasis. By referring to the underlying mechanisms of exercise-induced state fatigue, analysis of the etiology of the activity-dependent changes can be optimized. This knowledge can be used to apply acute and chronic interventions that specifically influence these mechanisms.
... Greater performance for the Wingate test was accompanied by lower RPEmuscular and RPEgeneral. These results are in line with previous research on the effects of caffeine supplementation, which reported a reduction in the relative RPE/velocity in a gradual progressive test [59], and lower RPE after a training session of 30 [60] and 90 min [61] at an intensity corresponding to 70% VO2max. Thus, caffeine seems to modify the relationship between workload and RPE, which could contribute to the Wavg improvement observed in the present study. ...
Objective:
The aim of this study was to investigate the effects of caffeine supplementation on: (i) psychological responses of subjective vitality and mood; (ii) performance through a Wingate test; and (iii) rate of perceived exertion (RPE) reported after a Wingate test.
Methods:
Fifteen male participants (22.60 ± 2.16 years) ingested 6 mg·kg-1 of caffeine or placebo (sucrose) supplementation in two experimental sessions. After 60 min from supplement intake, participants fulfilled two questionnaires, which measured subjective vitality and mood state, respectively. Subsequently, participants' performance was assessed through a Wingate test, which was followed by measurements of RPE at general, muscular, or cardiovascular level.
Results:
Caffeine supplementation increased some components of mood, as assessed by profile of mood states (POMS) (tension and vigor dimensions) and subjective vitality profiles, which were followed by a greater maximum power, average power, and lower time needed to reach maximum power during the Wingate test. Moreover, lower RPE, both at muscular and general levels were reported by participants after the Wingate test.
Conclusions:
These results suggest that caffeine supplementation exerts positive effects both in psychological and physical domains in trained subjects.
... Rating of perceived exertion (RPE; 1 -10 scale [25]) and subjective ratings for pleasantness (feeling scale; FS) using a 'feeling scale' (+2= very pleasant, 1= pleasant, 0= neutral, -1= unpleasant and -2= very unpleasant [26]), immediately followed by a standing cap- illary blood sample, after which the harness was removed. Participants then stepped off the treadmill and completed the RTI procedures in a standardized standing position, taking between 60 -90 s. ...
To determine the effect of carbohydrate mouth rinsing (CHO-MR) on physical and cognitive performance during repeated-sprints (RS) after 3 days of intermittent fasting (abstaining from food and fluid 14 h per day). In a randomized and counter-balanced manner 15 active healthy males in a fasted state performed a RS-protocol [RSP; 2 sets (SET1 and SET2) of 5×5 s maximal sprints, with each sprint interspersed with 25 s rest and 3 min of recovery between SET1 and SET2] on an instrumented non-motorized treadmill with embedded force sensors under three conditions: i) Control (CON; no-MR), ii) Placebo-MR (PLA-MR; 0% maltodextrin) and iii) CHO-MR (10% maltodextrin). Participants rinsed their mouth with either 10 mL of PLA-MR or CHO-MR solution for 5 s before each sprint. Sprint kinetics were measured for each sprint and reaction time (RTI) tasks (simple and complex) were assessed pre-, during- and post-RSP. There was no statistical main effect of CHO-MR on mean power, mean speed, and vertical stiffness during the sprints between the PLA-MR and CON condition. Additionally, no statistical main effect for CHO-MR on accuracy, movement time and reaction time during the RTI tasks was seen. CHO-MR did not affect physical (RSP) or cognitive (RTI) performance in participants who had observed 3 days of intermittent fasting (abstaining from food and fluid 14 h per day).
... Published findings on the effect of caffeine supplementation on RPE are mixed (Backhouse et al., 2011;De Morree et al., 2014;Doherty & Smith, 2005;Glaister et al., 2016;Meeusen et al., 2013). This study showed no significant differences in RPE at any measured point between the groups, although average RPE at the finish line was somewhat lower in the caffeine condition. ...
The ergogenic effect of caffeine on endurance exercise is commonly accepted. We aimed to elucidate realistically the effect of caffeine on triathlon event performance using a field study design, while allowing investigation into potential mechanisms at play. A double-blind, randomized, crossover, field trial was conducted. Twenty-six triathletes (14 males, 12 females) participated (age: 37.8±10.6 years, habitual caffeine intake: 413±505 mg/day, percentage body fat: 14.5±7.2%, training/week: 12.8±4.5 hours). Microencapsulated caffeine (6 mg/kg body weight) was supplemented 60 minutes pre-trial. Performance data included time to completion (TTC), rating of perceived exertion (RPE) and profile of mood states (POMS). Blood samples taken before, during and post-race were analyzed for cortisol, testosterone and full blood count. Capillary blood lactate concentrations were assessed pre-race, during transitions and 3, 6, 9, 12, 15 minutes after triathlons. Caffeine supplementation resulted in a 3.7% reduction in swim time (33.5±7.0 vs. 34.8±8.1 minutes, p<0.05) and a 1.3% reduction in TTC (149.6±19.8 vs. 151.5±18.6 minutes, p<0.05) for the whole group. Gender differences and individual responses are also presented. Caffeine did not alter RPE significantly, but better performance after caffeine supplementation suggests a central effect resulting in greater overall exercise intensity at the same RPE. Caffeine supplementation was associated with higher post-exercise cortisol levels (665±200 vs. 543±169 nmol/l, p<0.0001) and facilitated greater peak blood lactate accumulation (ANOVA main effect, p<0.05). We recommend that triathlon athletes with relatively low habitual caffeine intake may ingest 6 mg/kg body weight caffeine, 45-60 minutes before the start of Olympic-distance triathlon in order to improve performance.
... likely beneficial effect according to the magnitude-based inference analysis). Some have supported the notion that CAF may reduce the effort sensation during exercise through different mechanisms (Backhouse et al., 2011;de Morree et al., 2014;Kalmar and Cafarelli, 2004b;Plaskett and Cafarelli, 2001). de Morree et al. (2014) observed that ingestion of CAF reduced the primary motor cortex (Cz position) activation necessary to maintain a submaximal isometric knee extension at the very beginning of exercise, and this lowered Cz activation was correlated with a reduced RPE throughout the exercise. ...
Background: Ergogenic effects of caffeine (CAF) ingestion have been observed in different cycling exercise modes, and have been associated with alterations in ratings of perceived exertion (RPE). However, there has been little investigation of maximal oxygen uptake (VO2MAX) test outcomes. Aim: This study aimed to verify whether CAF may reduce RPE, thereby improving maximal incremental test (MIT) outcomes such as VO2MAX, time to exhaustion and peak power output (WPEAK). Methods: Nine healthy individuals performed three MITs (25 W/min until exhaustion) in a random, counterbalanced fashion after ingestion of CAF, placebo perceived as caffeine (PLA), and no supplementation (baseline control). VO2 was measured throughout the test, while RPE was rated according to overall and leg effort sensations. The power output corresponding to submaximal (RPE = 14 according to the 6–20 Borg scale) and maximal RPE was recorded for both overall (O-RPE14 and O-RPEMAX) and leg RPE (L-RPE14 and L-RPEMAX). Results: VO2MAX did not change significantly between
MITs; however, CAF and PLA increased time to exhaustion (~18.7% and ~17.1%, respectively; p < .05) and WPEAK (~13.0% and ~11.8%, respectively; p < .05) when compared with control. When compared with control, CAF ingestion reduced submaximal and maximal overall and leg RPEs, the effect being greater in maximal (likely beneficial in O-RPEMAX and L-RPEMAX) than submaximal RPE (possibly beneficial in O-RPE14 and L-RPE14). Similar results were found when participants ingested PLA. Conclusions: Compared with control, CAF and PLA improved MIT performance outcomes such as time to exhaustion and WPEAK, without altering VO2MAX values. CAF effects were attributed to placebo.
... Administration of caffeine did not improve this measure of visual attention, although it did promote higher subjective ratings of felt arousal and lower ratings of perceived exertion. The pattern observed in perceived exertion and arousal during the caffeine trial confirms adequate dosing, as our measures are consistent with previous reports documenting responses to caffeine during prolonged cycling exercise 48 . ...
... This pattern of neural activity is thought to promote a reduction in saccadic latency and lower task performance rates in gap trials 52,53 . Conversely, in the overlap trials, persistence of the fixation point during onset of the peripheral target promotes fixation-related neural activity after target appearance, causing slower saccade latencies 54 . Thus, it appears that exercise-induced fatigue does not selectively influence the release or maintenance of visual fixation, nor does it exert a general effect on the mechanisms underlying the disengagement and re-engagement of visual attention. ...
Fatigue-induced reductions in saccade velocity have been reported following acute, prolonged exercise. Interestingly, the detrimental impact of fatigue on oculomotor control can be prevented by a moderate dose of caffeine. This effect may be related to central catecholamine upregulation via caffeine’s action as an adenosine antagonist. To test this hypothesis, we compared the protective effect of caffeine on oculomotor control post-exercise to that of a norepinephrine-dopamine reuptake inhibitor. Within a placebo-controlled crossover design, 12 cyclists consumed placebo, caffeine or a norepinephrine-dopamine reuptake inhibitor (bupropion) during 180 minutes of stationary cycling. Saccades, smooth pursuit and optokinetic nystagmus were measured using infrared oculography. Exercise fatigue was associated with an 8 ± 11% reduction in the peak velocity of prosaccades, and a 10 ± 11% decrement in antisaccade peak velocity. Optokinetic nystagmus quick phases decreased in velocity by 15 ± 17%. These differences were statistically significant (p < 0.05). Norepinephrine-dopamine reuptake inhibition and caffeine prevented fatigue-related decrements in eye movement velocity. Pursuit eye movements and visual attention were unaffected. These findings show that norepinephrine-dopamine reuptake inhibition protects oculomotor function during exercise fatigue. Caffeine’s fatigue-reversing effects on eye movements appear to be mediated, at least in part, via modulation of central catecholamines.
... Administration of caffeine did not improve this measure of visual attention, although it did promote higher subjective ratings of felt arousal and lower ratings of perceived exertion. The pattern observed in perceived exertion and arousal during the caffeine trial confirms adequate dosing, as our measures are consistent with previous reports documenting responses to caffeine during prolonged cycling exercise 48 . ...
Strenuous exercise can result in an inability of the central nervous system to drive skeletal muscle effectively, a phenomenon known as central fatigue. The impact of central fatigue on the oculomotor system is currently unexplored. Fatigue that originates in the central nervous system may be related to perturbations in the synthesis and metabolism of several neurotransmitters. In this study we examine central fatigue in the oculomotor system after prolonged exercise. The involvement of central neurotransmission was explored by administering caffeine during exercise. Within a double-blind, randomized, repeated measures, crossover design, 11 cyclists consumed a placebo or caffeine solution during 180 min of stationary cycling. Saccadic eye movements were measured using infra-red oculography. Exercise decreased saccade velocity by 8% (placebo trial). This effect was reversed by caffeine, whereby velocity was increased by 11% after exercise. A non-oculomotor perceptual task (global motion processing) was unaffected by exercise. The human oculomotor system is impaired by strenuous exercise of the locomotor system. Caffeine exerts a protective effect on oculomotor control, which could be related to up-regulated central neurotransmission. In addition, cortical processes supporting global motion perception appear to be robust to fatigue.
... aerobic exercise bouts and the research agrees here too (Backhouse, Biddle, Bishop, and Williams, 2011). ...
... La adenosina es un neurotransmisor que actúa en la disminución de la actividad celular, inhibe la expresión de la dopamina (neurotransmisor que estimula la actividad del (SNC) y la transmisión sináptica del cerebro con la activación de sus receptores 64 . La cafeína por poseer una estructura molecular semejante a la de la adenosina, ocupa algunos de sus receptores y disminuye el efecto de este neurotransmisor en el organismo 50 . De esta manera, la dopamina pasa a ser menos estimulada. ...
Objective: To determine the potential ergogenic effects of energy drinks (ED) on aerobic and anaerobic exercise performance and describe their mechanisms of action. Methods: It was carried out a systematic review of literature PubMed/Medline and SportDiscus databases, having as inclusion criteria human studies reporting changes on aerobic physical performance and/or high-intensity exercise and short duration after consumption BE, published in English between January 1,2000 and December 31,2014. Results: After a filtering process, they were selected 20 studies, dealing 10 with changes in aerobic physical performance and 10 with anaerobic exercise performance. For the aerobic performance, they were assessed the following parameters: total exercise time, maximum oxygen consumption (VO2max) and the rate of perceived exertion (RPE). During anaerobic activities they were evaluated: muscular endurance and anaerobic power, anaerobic physical test and blood lactate. They were found some ergogenic effects after consumption of BE. In aerobic activity there was an increase in temporary capacity for exercise and a decrease in the subjective perception of fatigue. Regarding the anaerobic component, there was a better muscular response, contributing to an increase in muscle strength and a reduced time in sprints. However, some studies do not report any positive effect after consumption of BE, both in aerobic and anaerobic profile exercises. Conclusions: There is scientific evidence that the consumption of BE can improve some important parameters of aerobic and anaerobic exercise performance.
... The positive effect of caffeine on perception of effort is associated with changes in motor-related cortical activity during exercise [30], most likely in areas upstream of the primary motor cortex [31][32][33]. Caffeine can also reduce exercise-induced muscle pain [34,35], increase pleasure during exercise [36], and increase exercise enjoyment [37]. Importantly, caffeine can reduce perception of effort and exercise-induced muscle pain even at relatively low doses [38] and in habitual high caffeine consumers [39]. ...
... For example, women report higher RPE values compared to men at a given exercise intensity (Faulkner and Eston, 2007), whilst less fit individuals usually report higher RPE values at a given exercise intensity compared to persons with higher fitness levels (Faulkner and Eston, 2007). Participants have also reported higher RPE values when exercising at higher intensity (Al-Rahamneh and Eston, 2011), whilst participants have reported lower RPE values when exercising under caffeine conditions compared to a placebo (Backhouse et al., 2011). Participants have also reported higher RPE values when exercising under a carbohydratedepleted condition compared to a carbohydrate-replete condition (Noakes, 2004). ...
This study assessed: 1) the effect of fasted and non-fasted states on the relationships between RPE and V O 2 , HR V E during treadmill and cycling GXT; 2) the effect of fasted and non-fasted states on the affective state during the cycling and treadmill GXTs. Ten Muslim male physical education students (22.3 ± 1.5 y) volunteered for the study. Each student performed two GXTs while fasting during Ramadan (one on the treadmill and one on the bike) and the same two GXTs while not fasting after Ramadan. The relationships between the RPE and V E , the RPE andV O 2 and the RPE and HR were significantly higher (P < 0.05) in the non-fasted state compared to the fasted state (R 2 = 0.946 & R 2 = 0.872; R 2 = 0.949 & R 2 = 0.866; R 2 = 0.949 & R 2 = 0.829, respectively). There was no significant difference in the affective state between the fasted and non-fasted states (P > 0.05). RPE responses during the GXTs on treadmill and bike were affected during Ramadan fasting compared to a non-fasting state after Ramadan. This has very important implications especially when considering that there are numerous studies that have used sub-maximal RPE and V O 2 to predict V O 2 max. This may be due to the lower glucose level during Ramadan fasting as indicated by the lower respiratory exchange ratio in the fasted compared to the non-fasted state. However, the GXTs on treadmill and bike during Ramadan fasting were felt to be as pleasant as when not fasting after Ramadan.
... This field of inquiry exhibits great diversity, extending from basic neuroscience using animal models (Rasmussen & Hillman, 2011) to non-invasive studies in humans using blood assays (Raichlen, Foster, Gerdeman, Seillier, & Giuffrida, 2012), electroencephalography (Dishman, Thom, Puetz, O'Connor, & Clementz, 2010;Hall, Ekkekakis, & Petruzzello, 2010;Schneider, Askew, et al., 2009;Schneider, Graham, Grant, King, & Cooper, 2009;Woo, Kim, Kim, Petruzzello, & Hatfield, 2010) or functional neuroimaging (Boecker et al., 2008). An associated line of applied studies examines the influence of manipulating specific peripheral and central physiological variables, such as hydration, carbohydrate supplementation, or stimulation with caffeine (Backhouse, Biddle, Bishop, & Williams, 2011;Peacock, Thompson, & Stokes, 2012). ...
... Caffeine increases EE. Many studies have investigated the influence of caffeine on endurance exercise performance, muscle metabolism, and energy expenditure [4,5]. A possible mechanism by which caffeine affects thermogenesis involves inhibiting the phosphodiesterase-induced degradation of intracellular cyclic AMP [6,7]. ...
(A) Changes in oxygen uptake over 6 h in Experiment 1. (B) The sum of oxygen uptake over 2 h. Different superscripts mean significant differences among the groups (*P<0.05, **P<0.01, ***P<0.001).
(A) Respiratory exchange ratio (RER) over 6 h in Experiment 1. (B) Mean RER over 2 h. Different superscripts mean significant differences among the groups (**P<0.01, ***P<0.001, N.S., not significant).
(A) Carbohydrate oxidation over 6 h in Experiment 1. (B) The sum of carbohydrate oxidation over 2 h. Different superscripts mean significant differences among the groups (**P<0.01, ***P<0.001, N.S., not significant).
(A) Fat oxidation over 6 h in Experiment 1. (B) The sum of fat oxidation over 2 h. Different superscripts mean significant differences among the groups(***P<0.001, N.S., not significant).
(A) Changes in oxygen uptake over 6 h in Experiment 2. (B) The sum of oxygen uptake over 2 h. Different superscripts mean significant differences among the groups(***P<0.001, N.S., not significant).
(A) Changes in the respiratory exchange ratio (RER) over 6 h in Experiment 2. (B) Mean RER over 2 h. Different superscripts mean significant differences among the groups(***P<0.001, N.S., not significant).
(A) Changes in carbohydrate oxidation over 6 h in Experiment 2. (B) The Sum of carbohydrate oxidation over 2 h. Different superscripts mean significant differences among the groups (***P<0.001, N.S., not significant).
(A) Changes in fat oxidation over 6 h in Experiment 2. (B) The sum of fat oxidation over 2 h. Different superscripts mean significant differences among the groups (***P<0.001, N.S., not significant).
... For example, women report higher RPE values compared to men at a given exercise intensity (Faulkner and Eston, 2007), whilst low-fit individuals usually report higher RPE values at a given exercise intensity compared to persons with high fitness levels (Faulkner and Eston, 2007). Participants have also reported higher RPE values when exercising at higher intensity compared to low intensity (Al-Rahamneh and , whilst participants reported lower RPE values when exercising under caffeine conditions compared to a placebo (Backhouse et al., 2011). Participants have also reported higher RPE values when exercising under carbohydrate-depleted condition compared to carbohydrate-repleted condition (Noakes, 2004). ...
... Administration of caffeine did not improve this measure of visual attention, although it did promote higher subjective ratings of felt arousal and lower ratings of perceived exertion. The pattern observed in perceived exertion and arousal during the caffeine trial confirms adequate dosing, as our measures are consistent with previous reports documenting responses to caffeine during prolonged cycling exercise 48 . ...
... A metaanalysis of the relationship between caffeine and RPE concluded that caffeine is associated with a 5.6% decrease in RPE during constant rate exercise [12]. These findings were supported in a recent study in trained cyclists who were given caffeine before exercise and experienced attenuated RPE [13]. ...
Caffeine is a commonly used stimulant thought to have ergogenic properties. Most studies on the ergogenic effects of caffeine have been conducted in athletes. The purpose of this study was to test the hypothesis that caffeine reduces ratings of perceived exertion and increases liking of physical activity in sedentary adults. Participants completed treadmill walking at 60% to 70% of their maximal heart rate at baseline and for 6 subsequent visits, during which half of the participants were given caffeine (3 mg/kg) and half given placebo in a sports drink vehicle. To investigate the potential synergistic effects of acute and chronic caffeine on self-determined exercise duration, participants were rerandomized to either the same or different condition for the last visit, creating 4 chronic/acute treatment groups (placebo/placebo, placebo/caffeine, caffeine/placebo, caffeine/caffeine). Participants rated how much they liked the activity and perceived exertion at each visit. There was a main effect of time on liking of physical activity, with liking increasing over time and an interaction of sex and caffeine treatment on liking, with liking of activity increasing in female participants treated with caffeine, but not with placebo. There was no effect of caffeine on ratings of perceived exertion. Individuals who received caffeine on the final test day exercised for significantly longer than those who received placebo. These data suggest that repeated exposure to physical activity significantly increases liking of exercise and reduces ratings of perceived exertion and that caffeine does little to further modify these effects.
Three groups of energy drinks have been examined for sodium benzoate and caffeine using HPLC and spectrophotometer methods. Those brands include original UK brand which coded (RE), another two brands of (RL and B) which are imported from Austria to local companies, and the rest produced locally which are coded (T, FB, S and FE). The results showed that all brands contain sodium benzoate at different concentrations. FB brand comes out on top by containing around 416mg/l which was far above the permitted level by FAO/WHO, on the other hand the RE brand contained the lowest amount of sodium benzoate when analysed using HPLC. Results of caffeine examination showed that all samples contained lower levels of caffeine as it is claimed in their label to contain 300mg/l, in contrary to sodium benzoate the lowest concentration of caffeine found in the FB brand which was 13.78mg/l and the highest level of caffeine was found in FE brand which was 208.95mg/l. From the obtained results it is clear that none of the energy drink brands declared the actual content of both caffeine and sodium benzoate which usually required by food legislation and law. Therefore, it is considered as mislabelling which is recommended that the health authorities in our country to subject the local producers and the importers to present the required information on the labels without misleading consumers. It is also recommended to educate the population and put restriction on the local shops and supermarkets not to sell energy drinks to individuals under 16 years old.
The aim of the current study was to assess the effect of caffeine intake on maximal and sub-maximal physiological markers of exercise intensity and whether group (able-bodied and wheelchair users) moderated these findings. Ten able-bodied men (20.3±2.4 years, length 174.3±5.1 cm, 76.4±9.4 kg) and 9 wheelchair users (29.9±7.1 years, length 164±13 cm, 78.6±20.6 kg) participated in the study. Each participant performed 4 exercise tests. Two ramp exercise tests were used to assess the effect of caffeine intake on maximal values of power output (PO), oxygen uptake (VO 2 ), heart rate (HR), lactate and rate of perceived exertion (RPE): one performed with 6 mg/kg body mass of caffeine ingestion as gelatine capsules, and the second one with placebo. Two constant-load exercise tests at 70% PO peak to volitional exhaustion were used to assess the effect caffeine intake on sub-maximal values of VO 2 , HR, lactate and RPE: one performed with 6 mg/kg body mass of caffeine ingestion as gelatine capsules, and the second one with placebo. Two way ANOVA revealed that caffeine intake does not affect maximal values of VO 2 , HR, lactate and RPE (P>0.05). Caffeine intake reduced sub-maximal RPE at 5 min (P<0.05) and 10 min of exercise. Sub-maximal HR at 70% PO peak was higher in caffeine than placebo among wheelchair users (P<0.05). Time to exhaustion at 70% PO peak was significantly longer in caffeine than placebo (P<0.05). VO 2max and PO peak were significantly higher among able-bodied than wheelchair users (P<0.05). Caffeine has an effect on sub-maximal RPE and time to volitional exhaustion. Closed-loop exercise mode should be employed in future studies. Greater dosage of caffeine could be used but should not exceed the permitted amount of 12 mg/kg body mass. Wheelchair users should exercise and do more physical activity to enhance VO 2max and PO peak .
Background:
The purpose was to investigate the effect of caffeine (CAF) mouth rinse on peak power (PP), mean power (MP), peak power relative to body mass (rel PP), mean power relative to body mass (rel MP), fatigue index (FI) and anaerobic contribution in the Wingate test.
Methods:
Ten healthy men (age: 24.8 ± 3.7 years; body mass: 71.0 ± 7.8 kg; height: 170 ± 3 cm; body fat: 17.02 ± 4.9 %; VO2max: 44.15 ± 5.5 ml·kg-1·min-1) were recruited. A randomized, double-blind, cross-over design was employed. Participants were instructed to complete Wingate test in the fastest time possible under 2 conditions: CAF (25 ml of mint syrup with 1.2% of CAF, equivalent to 300 mg of CAF) and placebo (PLA) (25 ml of mint syrup without CAF).
Results:
There was no difference at PP (p = 0.66), MP (p = 0.16), rel PP (p = 0.82), rel MP (p = 0.18), FI (p = 0.19), anaerobic alactic (p = 0.71), anaerobic lactic (p = 0.25), total energy expenditure (p = 0.41) and peak plasma lactate concentration (p = 0.57).
Conclusions:
CAF mouth rinse did not increase peak power (PP), mean power (MP), peak power relative to body mass (rel PP), mean power relative to body mass (rel MP), fatigue index (FI) nor anaerobic contribution in the Wingate test.
Nutritional status has numerous effects on exercise metabolism and psychological responses. The effect of fed state on changes in affective valence; however, are unknown. Thus, the present study examined how fed state influenced self-selected exercise intensity, affective responses during exercise, and exercise enjoyment when exercise was completed following physical activity guidelines for public health. In a repeated-measures crossover design, 25 recreationally active men and women (age and BMI = 22.0 ± 2.0 yr and 24.3 ± 3.3 kg/m2) performed a single 30 min session of treadmill exercise at a Rating of Perceived Exertion (RPE) equal to 13 on the Borg 6-20 scale following an overnight fast (FAST) or 30 minutes after a small meal (FED). Affective valence was recorded every 3 minutes during exercise. Heart rate and gas exchange data were measured continuously using a metabolic cart, blood glucose and blood lactate concentration were measured pre/post-exercise, and enjoyment was measured 15 minutes post-exercise. There was no effect of condition on affective valence, enjoyment, or self-selected intensity (all p>0.05). However, pre-exercise blood glucose was higher in FED pre-exercise, but higher post-exercise in FAST (p<0.05). Blood lactate concentration was also higher in FAST (p<0.05). Our results reveal minimal effects of a small, high-carbohydrate pre-exercise meal on in-task and post-task affective responses, exercise enjoyment, and self-selected intensity. These data suggest that an overnight fast does not alter affective valence or reduce enjoyment of continuous exercise.
An ergogenic aid is defined as a substance, technique or device that directly improves exercise performance or indirectly removes constraints to exercise performance. Caffeine is one such substance and is a proven ergogenic aid for performance during endurance, load-incremented, short-term high-intensity and resistance exercise modalities. The primary mechanism of action seemingly responsible for caffeine’s ergogenic effect may be due to its antagonism of receptors for the neurotransmitter adenosine. Biochemically blocking adenosine receptors may have widespread effects on the body as a result of an increase in dopamine secretion. Dopamine increases attention, memory, motivation, and feelings of reward. Of importance to the present chapter, appropriate doses of caffeine can affect exercise performance while decreasing perceived exertion. All of these responses to caffeine ingestion can potentially improve exercise performance and PA adherence. In addition, blocking adenosine can decrease the activation of nociceptors, resulting in a blunted pain response to exercise. This chapter presents recent evidence for the ergogenic effects of caffeine during exercise as they pertain to perceived exertion, pain and affective responses. In addition, selected laboratory applications of the perceptual methodologies presented in previous chapters are proposed for use in studying the ergogenic effects of caffeine ingestion during exercise.
Strenuous exercise can result in an inability of the central nervous system to drive skeletal muscle effectively, a phenomenon known as central fatigue. The impact of central fatigue on the oculomotor system is currently unexplored. Fatigue that originates in the central nervous system may be related to perturbations in the synthesis and metabolism of several neurotransmitters. In this study we examine central fatigue in the oculomotor system after prolonged exercise. The involvement of central neurotransmission was explored by administering caffeine during exercise. Within a double-blind, randomized, repeated measures, crossover design, 11 cyclists consumed a placebo or caffeine solution during 180 min of stationary cycling. Saccadic eye movements were measured using infra-red oculography. Exercise decreased saccade velocity by 8% (placebo trial). This effect was reversed by caffeine, whereby velocity was increased by 11% after exercise. A non-oculomotor perceptual task (global motion processing) was unaffected by exercise. The human oculomotor system is impaired by strenuous exercise of the locomotor system. Caffeine exerts a protective effect on oculomotor control, which could be related to up-regulated central neurotransmission. In addition, cortical processes supporting global motion perception appear to be robust to fatigue.
Caffeine is consumed worldwide through a variety of sources. It is a popular stimulant known for its mood and cognitive enhancement, as well as its impact as an ergogenic aid for athletic performance. Primarily for running and cycling endurance events, 3-6mgkg-1 caffeine helps to increase time-to-exhaustion, promote a greater work capacity, and reduce perceived exertion. Caffeine peaks in the blood within 30-75 minutes after consumption, so timing is an important component to its effects on performance. A person's caffeine intake, including dosing and timing, should be based on individual tolerance. The effect of caffeine weakens over time in habitual users, so to maximize athletic performance, one should abstain from caffeine for at least 7 days prior to an athletic event. Likewise, if using caffeine to enhance performance, an individual should experiment with caffeine intake prior to the event, as it can produce negative side effects in the caffeine naïve individual. An average intake of <400mg/day is shown to be safe for a healthy person, but individual variation should be borne in mind. Provided that one remembers the importance of dosing, timing, and frequency of caffeine intake, combined with a person's habitual intake, caffeine can be a successful tool to enhance cognition, alertness, and athletic performance.
Background: Exercise improves cognition, but whether fitness status and caffeine modulate this effect remains unclear. Purpose: To determine if sustained attention is improved following exercise with and without caffeine in endurance-trained vs. sedentary adults. Methods: A continuous performance task (CPT), that is, a 20 min measure of sustained attention to assess accuracy and precision, was used to induce mental fatigue. Following the 20 min CPT, trained (n = 12) and sedentary (n = 12) participants completed either 30-min rest or 30-min moderate-intensity cycling below lactate threshold. Exercise trials were completed with placebo and caffeine (3 mg/kg) followed by cycling to volitional fatigue. Results: Exercise, as compared to rest, improved (p
Regular physical activity is important for a healthy lifestyle. The physical activity should be performed with the right individual intensity. Today it is common to use the heart rate as indicator for the optimal individual training intensity, but the subjective intensity of the trainee is not considered. In this paper we present an approach which focuses on the perceived exertion of the trainee and helps to reach and keep a user-defined intensity level.
Combining an exercise and nutritional intervention is arguably the optimal method of creating energy imbalance for weight loss. This study sought to determine if combining exercise and caffeine supplementation was more effective for promoting acute energy deficits and manipulations to substrate metabolism than exercise alone. Fourteen recreationally-active participants (Mean ± SD BMI: 22.7 ± 2.6 kg∙m-2) completed a resting control trial (CON), a placebo exercise trial (EX), and a caffeine exercise trial (EX+CAF, 2x 3 mg∙kg-1 of caffeine 90 min before and 30 min after exercise) in a randomized, double-blinded design. Trials were 4 h in duration with 1 h of rest, 1 h of cycling at ~65 % power at VO2max or rest, and a 2 h recovery. Gas exchange, appetite perceptions, and blood samples were obtained periodically. Two hours after exercise, participants were offered an ad libitum test meal where energy and macronutrient intake were recorded. EX+CAF resulted in significantly greater energy expenditure and fat oxidation compared to EX (+250 kJ; +10.4 g) and CON (+3126 kJ; +29.7 g) (P < 0.05). A trend for reduced energy and fat intake compared to CON (-718 kJ; -8 g) (P = 0.055) was observed. Consequently, EX+CAF created a greater energy deficit (P < 0.05). Caffeine also led to exercise being perceived as less difficult and more enjoyable (P < 0.05). Combining caffeine with exercise creates a greater energy deficit and the implications of this protocol for weight loss or maintenance over longer time periods in overweight/obese populations require further investigation.
Purpose
– The paper aims to describe the effects of caffeine intake on exercise performance as well on diabetes, cirrhosis and asthma.
Design/methodology/approach
– The review includes the most updated studies found in Pub‐Med all of which are in relation to caffeine and exercise performance as well as its effects on disease issues.
Findings
– The majority of studies show that caffeine ingestion of about 6 mg of body weight mass may have a positive effect on endurance and anaerobic exercise performance. In addition, if it is consumed together with carbohydrates, it may also improve post‐recovery glycogen synthesis. Intake of caffeine was also found to have a positive effect on the prevention of liver cirrhosis, reducing asthma attacks and lowering the risk of type 2 diabetes.
Originality/value
– The paper gives information to nutritionists, clinical dietitians and sports nutritionists on the newest data about the effects of caffeine on exercise performance and disease issues.
The purpose of this study was to investigate the influence of an energy drink (ED) on cycling performance and immune-related variables. Eleven trained male cyclists (33.4 ± 8.9 yr, 81 ± 7.6 kg, maximal VO2 52 ± 3.4 ml[BULLET OPERATOR]kg[BULLET OPERATOR]min) consumed 500 mL of 1)ED (2.0g taurine, 1.2 g glucuronolactone, 160mg caffeine, 56g carbohydrate (CHO), and B vitamins), 2) cola matched for caffeine and CHO (CC), or 3) flavored placebo (PL- sparking water and flavoring) 50 min prior to racing in a randomized, cross-over design. Performance was measured as time to complete (TTC) a 25-mile simulated road race. Blood was collected at baseline (BASE), 30 minutes after drink consumption (PODR), during exercise at miles 5 (M5), 15 (M15), and immediately (POEX) and 30 min post-exercise (30minPO). TTC was not different (p>0.05) among trials (ED 68.6 ± 2.7, CC 68.9 ± 3.8, PL 69.6 ± 3.8 min). CC and ED elicited a mile hypoglycemia during cycling. POEX IL-6 was greatest after ED while CC IL-6 was greater than PL (10.2±1.6, 6.7±0.6, 4.8±0.7 pg[BULLET OPERATOR]ml, respectively, p<0.001). Cycling increased leukocyte number in all conditions with ED leukocyte number greater than that of PL at M15 (9.8±0.6, 8.5±0.3 x10 cells[BULLET OPERATOR]mL). ED induced an earlier recruitment of monocytes to the blood stream than CC. Mean fat oxidation was greater in PL compared to CC (0.43±0.06, 0.28±0.04 g[BULLET OPERATOR]min, p=0.033), but did not differ between ED (0.32±0.06) and PL. Lactate was higher in ED compared to CC and PL at M5 and M15(p=0.003), but there was no significant influence of either ED or CC on performance. CHO and caffeine consumption prior to endurance cycling significantly increased the IL-6 release and leukocytosis, and the additional ingredients in ED appear to have further augmented these responses.
This review summarizes properties, health effects and analytical methods for determination of caffeine.
This study examined the effects of a carbohydrate-electrolyte drink on voluntary fluid intake, affect and self-selected intensity during recreational exercise after fluid restriction. In a randomised counterbalanced design, ten physically active adults were dehydrated via a 24-h period of fluid restriction before completing two 20-min bouts of cardiovascular exercise, 20-min of resistance exercise and 20 min on a cycle ergometer at a self-selected intensity with ad libitum access to water (W) or a carbohydrate-electrolyte solution (CES). Fluid restriction induced hypohydration of ∼1.2% initial body mass. Fluid intake during exercise was greater with CES (2105 ± 363 vs. 1470 ± 429 mL; P<0.01) and resulted in more adequate hydration (-0.03 ± 0.65 vs. -1.26 ± 0.80%; P<0.01). Plasma glucose concentrations (4.48 ± 0.40 vs. 4.28 ± 0.32 mmol⋅L(-1); P<0.01) and pleasure ratings (2.63 ± 1.17 vs. 1.81 ± 1.37; P<0.01) were greater with CES than W. Mean power output during exercise performed at a self-selected intensity was 5.6% greater with CES (171 ± 63 vs. 162 ± 60 Watts; P<0.05). In physically active adults performing a 'real-life' recreational exercise simulation, CES resulted in more adequate hydration and an enhanced affective experience that corresponded with an increase in self-selected exercise intensity.
Affective states and the cognitive appraisal of exertion during exercise may determine whether or not an individual will persist at an activity. Relationships among affect, cognition, and sensory information (physiological cues) are predicted by the parallel-processing model. The purpose of this study was to examine (a) changes in affect and perceived exertion; (b) the relationship of affect to perceived exertion; and (c) the relationship of affect and perceived exertion to the physiological cues of heart rate, ventilation, and glucose during a two-hour run. Results revealed that as exercise continued, perceived exertion increased and affect became more negative. In addition, as running continued after 60 min the magnitude of the negative relationship of affect to RPE increased slightly. It was expected that as fatigue increased, physiological cues would become more salient and their relationship to perceived exertion and affect would increase. This did not occur. Instead RPE maintained a consistent moderate positive relationship with ventilation and demonstrated a moderate negative relationship with plasma glucose after 90 min of running. Whereas affect demonstrated a moderate positive relationship with plasma glucose after 90 min of running. These results demonstrated that while running at a moderate intensity affect became more negative, RPE increased and physiological cues related to affect and RPE differed as the run continued beyond 60 min.
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.
Factor-analytic evidence has led most psychologists to describe affect as a set of dimensions, such as displeasure, distress, depression, excitement, and so on, with each dimension varying independently of the others. However, there is other evidence that rather than being independent, these affective dimensions are interrelated in a highly systematic fashion. The evidence suggests that these interrelationships can be represented by a spatial model in which affective concepts fall in a circle in the following order: pleasure (0), excitement (45), arousal (90), distress (135), displeasure (180), depression (225), sleepiness (270), and relaxation (315). This model was offered both as a way psychologists can represent the structure of affective experience, as assessed through self-report, and as a representation of the cognitive structure that laymen utilize in conceptualizing affect. Supportive evidence was obtained by scaling 28 emotion-denoting adjectives in 4 different ways: R. T. Ross's (1938) technique for a circular ordering of variables, a multidimensional scaling procedure based on perceived similarity among the terms, a unidimensional scaling on hypothesized pleasure–displeasure and degree-of-arousal dimensions, and a principal-components analysis of 343 Ss' self-reports of their current affective states. (70 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Caffeine is the most widely consumed centralnervous-system stimulant. Three main mechanisms of action of caffeine on the central nervous system have been described. Mobilization of intracellular calcium and inhibition of specific phosphodiesterases only occur at high non-physiological concentrations of caffeine. The only likely mechanism of action of the methylxanthine is the antagonism at the level of adenosine receptors. Caffeine increases energy metabolism throughout the brain but decreases at the same time cerebral blood flow, inducing a relative brain hypoperfusion. Caffeine activates noradrenaline neurons and seems to affect the local release of dopamine. Many of the alerting effects of caffeine may be related to the action of the methylxanthine on serotonine neurons. The methylxanthine induces dose-response increases in locomotor activity in animals. Its psychostimulant action on man is, however, often subtle and not very easy to detect. The effects of caffeine on learning, memory, performance and coordination are rather related to the methylxanthine action on arousal, vigilance and fatigue. Caffeine exerts obvious effects on anxiety and sleep which vary according to individual sensitivity to the methylxanthine. However, children in general do not appear more sensitive to methylxanthine effects than adults. The central nervous system does not seem to develop a great tolerance to the effects of caffeine although dependence and withdrawal symptoms are reported.
0895-2779 The exercise psychology literature includes an intriguing, albeit not frequently discussed, paradox by juxtaposing two conclusions: (a) that exercise makes most people feel better and (b) that most people are physically inactive or inadequately active. In this article, we propose that this might be an artifact rather than a paradox. Specifically, we question the generality of the conclusion that exercise makes people feel better by proposing that (a) occasional findings of negative affective changes tend to be discounted, (b) potentially relevant negative affective states are not always measured, (c) examining changes from pre- to postexercise could miss negative changes during exercise, and (d) analyzing changes only at the level of group aggregates might conceal divergent patterns at the level of individuals or subgroups. Data from a study of 12 men participating in a 90-min walk–run protocol designed to simulate the demands of sports games (e.g., soccer) are used to illustrate these points. Published Refereed
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.
There is little evidence regarding the benefits of caffeine ingestion on cognitive function and skillful actions during sporting performance, especially in sports that are multifaceted in their physiological, skill, and cognitive demands.
To examine the influence of caffeine on performance during simulated soccer activity.
Twelve male soccer players completed two 90-min soccer-specific intermittent running trials interspersed with tests of soccer skill (LSPT). The trials were separated by 7 days and adhered to a randomized crossover design. On each occasion participants ingested 6 mg/kg body mass (BM) of caffeine (CAF) or a placebo (PLA) in a double-blind fashion 60 min before exercise. Movement time, penalties accrued, and total time were recorded for the LSPT. Physiological and performance markers were measured throughout the protocol. Water (3 ml/kg BM) was ingested every 15 min.
Participants accrued significantly less penalty time in the CAF trial (9.7 +/- 6.6 s vs. PLA 11.6 +/- 7.4 s; p = .02), leading to a significantly lower total time in this trial (CAF 51.6 +/- 7.7 s vs. PLA 53.9 +/- 8.5 s; p = .02). This decrease in penalty time was probably attributable to an increased passing accuracy in the CAF trial (p = .06). Jump height was 2.7% (+/- 1.1%) higher in the CAF trial (57.1 +/- 5.1 cm vs. PLA 55.6 +/- 5.1 cm; p = .01).
Caffeine ingestion before simulated soccer activity improved players' passing accuracy and jump performance without any detrimental effects on other performance parameters.
Caffeine is thought to act as a central stimulant and to have effects on physical, cognitive, and psychomotor functioning.
To examine the effects of ingesting a performance bar, containing caffeine, before and during cycling exercise on physical and cognitive performance.
Twenty-four well-trained cyclists consumed the products [a performance bar containing 45 g of carbohydrate and 100 mg of caffeine (CAF), an isocaloric noncaffeine performance bar (CHO), or 300 mL of placebo beverage (BEV)] immediately before performing a 2.5-h exercise at 60% VO2max followed by a time to exhaustion trial (T2EX) at 75% VO2max. Additional products were taken after 55 and 115 min of exercise. Cognitive function measures (computerized Stroop and Rapid Visual Information Processing tests) were performed before exercise and while cycling after 70 and 140 min of exercise and again 5 min after completing the T2EX ride.
Participants were significantly faster after CAF when compared with CHO on both the computerized complex information processing tests, particularly after 140 min and after the T2EX ride (P < 0.001). On the BEV trial, performance was significantly slower than after both other treatments (P < 0.0001). There were no speed-accuracy tradeoffs (P > 0.10). T2EX was longer after CAF consumption compared with both CHO and BEV trials (P < 0.05), and T2EX was longer after CHO than after BEV (P < 0.05). No differences were found in the ratings of perceived exertion, mean heart rate, and relative exercise intensity (% VO2max; P > 0.05).
Caffeine in a performance bar can significantly improve endurance performance and complex cognitive ability during and after exercise. These effects may be salient for sports performance in which concentration plays a major role.
The alerting effects of caffeine were assessed using a standard physiological measure of daytime sleepiness/alertness, the Multiple Sleep Latency Test (MSLT). Healthy young men (n = 24) were randomly assigned to receive caffeine 250 mg or placebo administered double blind, at 0900 and 1300 hours on each of 2 days. On the 3rd day both groups received placebo to test for conditioning to the alerting effects of caffeine. Each day sleep latency was measured at 1000, 1200, 1400, and 1600 hours and performance (divided attention at 1030 hours and auditory vigilance at 1430 hours) was assessed. Caffeine increased sleep latency (i.e., improved alertness) and auditory vigilance performance compared to placebo. Tolerance to the effects of caffeine on sleep latency developed over the four administrations. On the conditioning test (day 3) the group receiving caffeine the previous two days was more alert and performed better than the placebo group.
The effects of three carbohydrate electrolyte solutions (CES) containing different amounts of caffeine on cognitive function and the combined effects of these drinks and exercise on cognitive functions were investigated in a double-blind, cross-over study. On five separate occasions, fifteen endurance trained male athletes (23.3 years) received water placebo, CES placebo (68.8 g/l), and three CES drinks containing low, medium and high dosages of caffeine (150, 225 and 320 mg/l). Each occasion, 8 ml/kg of the drink was consumed before -- and 6 ml/kg of the drink was consumed during an all-out 1 hour time trial on a bicycle ergometer. Cognitive (attentional, psychomotor, and memory) tests were carried out immediately before and immediately after exercise. Before exercise, long term memory was improved by CES plus low dose caffeine compared to both placebos. Immediately after exercise, all cognitive functions were improved by CES plus low- and medium-dose caffeine compared to placebo. These results comprise the first practical demonstration of the cognition improving effects of low amounts of caffeine in CES after strenuous physical exercise.
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 been 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.
This paper addresses areas where there is controversy regarding caffeine as an ergogenic aid and also identifies topics that have not been adequately addressed. It is clear that caffeine, in moderate amounts, can be used orally as an ergogenic aid in aerobic activity lasting for more than 1 min. It increases endurance and speed, but not maximal VO2 and related parameters. While there are fewer well-controlled studies for resistance exercise, the literature would suggest similar improvements: increased endurance at submaximal tension and power generated in repeated contractions and no change in maximal ability to produce force. It is likely that theophylline (a related methylxanthine) has similar actions and it has been suggested that the combination of caffeine and sympathomimetics may be a more potent erogenic aid. The voids in our understanding of caffeine include the dose (what amount is optimal, what vehicle is used to deliver the drug as well as method, pattern, and mode of administration), the potential side effects (particularly in competitive settings), health implications (insulin resistance and if combined with ephedrine, cardiovascular risks) and mechanisms of action. It appears unlikely that increased fat oxidation and glycogen sparing is the prime ergogenic mechanism.
The literature suggests that the following effects on behavior of adult humans may occur when individuals consume moderate amounts of caffeine. (1) Caffeine increases alertness and reduces fatigue. This may be especially important in low arousal situations (e.g. working at night). (2) Caffeine improves performance on vigilance tasks and simple tasks that require sustained response. Again, these effects are often clearest when alertness is reduced, although there is evidence that benefits may still occur when the person is unimpaired. (3) Effects on more complex tasks are difficult to assess and probably involve interactions between the caffeine and other variables which increase alertness (e.g. personality and time of day). (4) In contrast to the effects of caffeine consumption, withdrawal of caffeine has few effects on performance. There is often an increase in negative mood following withdrawal of caffeine, but such effects may largely reflect the expectancies of the volunteers and the failure to conduct "blind" studies. (5) Regular caffeine usage appears to be beneficial, with higher users having better mental functioning. (6) Most people are very good at controlling their caffeine consumption to maximise the above positive effects. For example, the pattern of consumption over the day shows that caffeine is often consumed to increase alertness. Indeed, many people do not consume much caffeine later in the day since it is important not to be alert when one goes to sleep. In contrast to effects found from normal caffeine intake, there are reports that have demonstrated negative effects when very large amounts are given or sensitive groups (e.g. patients with anxiety disorders) were studied. In this context caffeine has been shown to increase anxiety and impair sleep. There is also some evidence that fine motor control may be impaired as a function of the increase in anxiety. Overall, the global picture that emerges depends on whether one focuses on effects that are likely to be present when caffeine is consumed in moderation by the majority of the population or on the effects found in extreme conditions. The evidence clearly shows that levels of caffeine consumed by most people have largely positive effects on behavior. Excessive consumption can lead to problems, especially in sensitive individuals.
OBJECTIVES: High exercise intensity may be associated with reduced adherence to exercise programmes, possibly because it is perceived as aversive. However, several authors have suggested that an intensity as high as 60% or 70% of maximal aerobic capacity (VO(2max)) is necessary for exercise to elicit positive affective changes. To elucidate this discrepancy, the affective responses to increasing levels of exercise intensity were examined. DESIGN: In total, 30 volunteers rated their affect every minute as they ran on a treadmill while the speed and grade were progressively increased. METHOD: The methodology was unique in three respects: (1) affect was assessed in terms of the dimensions of the circumplex model instead of distinct affective states, (2) affect was assessed repeatedly before, during, and after exercise, not only before and after, and (3) exercise intensity was standardized across participants in terms of metabolically comparable phases (beginning, ventilatory threshold, VO(2max)) instead of percentages of maximal capacity. RESULTS: Pre-to-post-exercise comparisons indicated affective benefits in the form of increased energetic arousal and decreased tense arousal. During exercise, however, affective valence deteriorated beyond the ventilatory threshold and until VO(2max), a trend that reversed itself instantaneously during cool-down. CONCLUSIONS: Exercise intensity that requires a transition to anaerobic metabolism can have a transient but substantial negative impact on affect and this may, in turn, reduce adherence to exercise programmes.
Negative affective states such as depression are associated with premature mortality and increased risk of coronary heart disease, type 2 diabetes, and disability. It has been suggested that positive affective states are protective, but the pathways through which such effects might be mediated are poorly understood. Here we show that positive affect in middle-aged men and women is associated with reduced neuroendocrine, inflammatory, and cardiovascular activity. Positive affect was assessed by aggregating momentary experience samples of happiness over a working day and was inversely related to cortisol output over the day, independently of age, gender, socioeconomic position, body mass, and smoking. Similar patterns were observed on a leisure day. Happiness was also inversely related to heart rate assessed by using ambulatory monitoring methods over the day. Participants underwent mental stress testing in the laboratory, where plasma fibrinogen stress responses were smaller in happier individuals. These effects were independent of psychological distress, supporting the notion that positive well-being is directly related to health-relevant biological processes.
• cortisol
• well-being
• fibrinogen
• heart rate
This study was designed to determine the effects of ingesting a carbohydrate (CHO) solution on affective states and rating of perceived exertion (RPE) during prolonged intermittent high-intensity exercise. Seventeen male soccer players completed a prolonged intermittent high-intensity exercise protocol for 90 min on two occasions, separated by at least 7 days. Participants consumed either a 6.4% CHO (0.6 g/kg body mass (BM)/h) or an artificially sweetened placebo (PLA) solution immediately before (8 mL/kg BM) and every 15 min (3 mL/kg BM) during exercise in a double-blind, counterbalanced design. Pleasure-displeasure, perceived activation, RPE and plasma glucose concentration was assessed. The results showed that compared with the CHO trial, perceived activation were lower in the placebo trial during the last 30 min of exercise and this was accompanied by lowered plasma glucose concentrations. In the CHO trial, RPE was maintained in the last 30 min of exercise but carried on increasing in the PLA trial. Therefore, CHO ingestion during prolonged high-intensity exercise appears to elicit an enhanced perceived activation profile that may impact upon task persistence and performance. This finding is in addition to the physiological and metabolic benefits of the exogenous energy supply.
Caffeine is the most popular psychoactive substance in the world, and one of the widest-traded commodities in the forms of coffee, tea and cola soft drinks. But is consumption of caffeine safe in terms of physical and mental health? Addressing this question, the author traces how caffeine consumption evolved as well as how caffeine is absorbed, distributed and metabolized in our bodies. He then discusses the effects of caffeine on: psychomotor and cognitive performance; psychological well-being; blood pressure and cardiovascular health; carcinogenic potentials; pregnancy and perinatal health; athletic performance; and diagnostic and therapeutic applications. The book addresses the question of whether caffeine is a drug of abuse, and summarizes the main conclusions to be drawn from the vast body of relevant science.
10 18–23 yr old telic-dominant and 10 20–22 yr old paratelic-dominant Ss performed a task that represented a video car-racing simulation. 12 of these Ss were interviewed on what they did the previous day, lifestyle, and planning orientation. Data obtained from a survey (110 undergraduates measured for telic or paratelic dominance), the task, and the interview support the construct validity of the telic (serious-minded, planning oriented, arousal avoiding) and paratelic (playful, here-and-now oriented, arousal seeking) constructs. Physiological measurements taken during task performance showed that telic Ss had steeper EMG gradients, higher tonic skin conductance, and greater thoracic respiratory amplitudes than did paratelic Ss. (28 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
232 undergraduates participated in 3 experiments that evaluated the feeling scale (FS) by W. J. Rejeski et al (1987) as a measure of affect during exercise. In Exp 1, Ss were instructed to check adjectives on the Multiple Affective Adjective Checklist—Revised that they would associate with either a "good" or a "bad" feeling during exercise. As predicted, discriminant function analysis indicated that the good/bad dimension of the FS appears to represent a core of emotional expression. In Exp 2, Ss rated how they felt during exercise at 3 rates of perceived exertion (RPE). Exp 3 involved 3 4-min bouts of exercise at 30, 60, and 90% of maximum oxygen consumption. RPE and the FS were moderately related, but only at easy and hard workloads. FS ratings evidenced greater variability as metabolic demands increased, and RPEs consistently had stronger ties to physiologic cues than responses to the FS. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
An analysis was made of data from over 4000 postepisiotomy, uterine cramping, and postsurgical patients complaining of moderate or severe pain. They had received 325, 650, or 1300 mg aspirin or placebo while they were subjects in 10 analgesic clinical trials. On the average, for the same verbally expressed pain intensity level and the same treatment, more relief was obtained by a patient with uterine cramping than one with episiotomy pain, who in turn obtained more relief than a patient with surgical pain. A new mathematical model which characterizes the probability that an analgesic provides complete relief as a function of dose, severity of pain intensity, and pain etiology is developed. The model utilizes the data itself to estimate the numerical score corresponding to verbal pain intensities. The results indicate that the numerical score quantifying severe surgical pain is 1.4 times greater than the score for severe episiotomy pain, which in turn is 3.2 times greater than the score for severe uterine cramping. Clinical trials must be designed to take these differences into account. Also, clinicians must be cognizant of such differences when choosing among drugs and dosages for patients with different pain intensity and etiology.
There is a great demand for perceptual effort ratings in order to better understand man at work. Such ratings are important complements to behavioral and physiological measurements of physical performance and work capacity. This is true for both theoretical analysis and application in medicine, human factors, and sports. Perceptual estimates, obtained by psychophysical ratio-scaling methods, are valid when describing general perceptual variation, but category methods are more useful in several applied situations when differences between individuals are described. A presentation is made of ratio-scaling methods, category methods, especially the Borg Scale for ratings of perceived exertion, and a new method that combines the category method with ratio properties. Some of the advantages and disadvantages of the different methods are discussed in both theoretical-psychophysical and psychophysiological frames of reference.
Potential ergogenic effects of caffeine at the cellular level are mediated by three main mechanisms of action which are: intracellular mobilization of calcium from sarcoplasmic reticulum and increased sensitivity of myofibrilles to calcium; inhibition of phosphodiesterases leading to an increase in cyclic-3',5'-adenosine monophosphate (cAMP) in various tissues including muscle; and the antagonism at the level of adenosine receptors, mainly in the central nervous system. The main mechanism of action of caffeine at the level usually encountered in vivo after the ingestion of a few cups of coffee is undoubtedly linked to the antagonism of caffeine at adenosine receptors. Caffeine also increases production of plasma catecholamines that allow the body to adapt to the stress created by physical exercise. Catecholamine production increases probably, in turn, the availability of free fatty acids as muscle substrates during work, thus allowing glycogen sparing. Caffeine is able to increase muscle contractility, has no ergogenic effect on intense exercise of brief duration, but can improve the time before exhaustion. Caffeine is also able to improve physical performance and endurance during prolonged activity of submaximal intensity. Glycogen sparing resulting from increased rate of lipolysis could contribute to the prolonged time to exhaustion. Finally, tolerance to the methylxanthine should be taken into account when an athlete wants to draw any benefit from caffeine absorption prior to a sports event.
Caffeine is present in many widely consumed drinks and some foods. In the fairly extensive literature on the psychostimulant effects of caffeine, there are few dose-response studies and even fewer studies of the effects of doses of caffeine lower than 50 mg (the range of the amounts of caffeine contained in, for example, a typical serving of tea or cola).
This study measured the effects of 0, 12.5, 25, 50 and 100 mg caffeine on cognitive performance, mood and thirst in adults with low and moderate to high habitual caffeine intakes.
This was a double-blind, within-subjects study. Following overnight caffeine abstinence, participants (n=23) completed a test battery once before and three times after placebo or caffeine administration. The test battery consisted of two performance tests, a long duration simple reaction time task and a rapid visual information processing task, and a mood questionnaire (including also an item on thirst).
Effects on performance and mood confirmed a psychostimulant action of caffeine. All doses of caffeine significantly affected cognitive performance, and the dose-response relationships for these effects were rather flat. The effects on performance were more marked in individuals with a higher level of habitual caffeine intake, whereas caffeine increased thirst only in low caffeine consumers.
After overnight caffeine abstinence, caffeine can significantly affect cognitive performance, mood and thirst at doses within and even lower than the range of amounts of caffeine contained in a single serving of popular caffeine-containing drinks. Regular caffeine consumers appear to show substantial tolerance to the thirst-increasing but not to the performance and mood effects of caffeine.
This study was designed to examine the effects of carbohydrate-electrolyte ingestion on physical and mental function associated with the performance of intermittent high-intensity (IHI) exercise similar to many common competitive sporting events.
Physically active men (N = 5) and women (N = 5), experienced in competitive soccer or basketball, completed three practice sessions and two experimental trials of an IHI shuttle running protocol designed to closely stimulate the demands of an actual competitive sporting event such as basketball. The experimental trials consisted of four 15-min quarters (QTR) of intermittent shuttle running at various percentages of .VO(2max) (walking, jogging, running, sprinting and jumping), separated by a 20-min halftime rest period (HALF) and followed by a shuttle run to fatigue. Various tests of physical and mental function (shuttle run to fatigue, 20-m maximal sprint, 10-repetition maximal vertical jumping, whole body motor skill test (MS-Test), profile of mood states (POMS), and Stroop Color-Word Test) were performed throughout the experimental trial. Carbohydrate-electrolyte (CHO) or placebo (P) drinks were consumed before exercise (5 mL.kg(-1); 6% solution) and at halftime (5 mL.kg(-1); 18% solution). Smaller volumes (3 mL.kg(-1); 6% solution) were given after QTR-1, HALF, QTR-3, and QTR-4.
CHO ingestion resulted in a 37% longer run time to fatigue and faster 20-m sprint time during QTR-4 (P < 0.05). MS-Test performance was also improved during the latter stages of exercise along with self-reported perceptions of fatigue (subscale of POMS) (P < 0.05) in CHO versus P.
These results suggest a beneficial role of carbohydrate-electrolyte ingestion on physical and mental function during intermittent exercise similar to that of many competitive team sports.
Caffeine ingestion can delay fatigue during exercise, but the mechanisms remain elusive. This study was designed to test the hypothesis that blockade of central nervous system (CNS) adenosine receptors may explain the beneficial effect of caffeine on fatigue. Initial experiments were done to confirm an effect of CNS caffeine and/or the adenosine A(1)/A(2) receptor agonist 5'-N-ethylcarboxamidoadenosine (NECA) on spontaneous locomotor activity. Thirty minutes before measurement of spontaneous activity or treadmill running, male rats received caffeine, NECA, caffeine plus NECA, or vehicle during four sessions separated by approximately 1 wk. CNS caffeine and NECA (intracerebroventricular) were associated with increased and decreased spontaneous activity, respectively, but caffeine plus NECA did not block the reduction induced by NECA. CNS caffeine also increased run time to fatigue by 60% and NECA reduced it by 68% vs. vehicle. However, unlike the effects on spontaneous activity, pretreatment with caffeine was effective in blocking the decrease in run time by NECA. No differences were found after peripheral (intraperitoneal) drug administration. Results suggest that caffeine can delay fatigue through CNS mechanisms, at least in part by blocking adenosine receptors.
Effects of caffeine and fatigue are discussed with special attention to adenosine-dopamine interactions. Effects of caffeine on human cognition are diverse. Behavioural measurements indicate a general improvement in the efficiency of information processing after caffeine, while the EEG data support the general belief that caffeine acts as a stimulant. Studies using ERP measures indicate that caffeine has an effect on attention, which is independent of specific stimulus characteristics. Behavioural effects on response related processes turned out to be mainly related to more peripheral motor processes. Recent insights in adenosine and dopamine physiology and functionality and their relationships with fatigue point to a possible modulation by caffeine of mechanisms involved in the regulation of behavioural energy expenditure.
The purpose of this study was to use the meta-analytic approach to examine the effects of caffeine ingestion on ratings of perceived exertion (RPE). Twenty-one studies with 109 effect sizes (ESs) met the inclusion criteria. Coding incorporated RPE scores obtained both during constant load exercise (n=89) and upon termination of exhausting exercise (n=20). In addition, when reported, the exercise performance ES was also computed (n=16). In comparison to placebo, caffeine reduced RPE during exercise by 5.6% (95% CI (confidence interval), -4.5% to -6.7%), with an equivalent RPE ES of -0.47 (95% CI, -0.35 to -0.59). These values were significantly greater (P<0.05) than RPE obtained at the end of exercise (RPE % change, 0.01%; 95% CI, -1.9 to 2.0%; RPE ES, 0.00, 95% CI, -0.17 to 0.17). In addition, caffeine improved exercise performance by 11.2% (95% CI; 4.6-17.8%). Regression analysis revealed that RPE obtained during exercise could account for approximately 29% of the variance in the improvement in exercise performance. The results demonstrate that caffeine reduces RPE during exercise and this may partly explain the subsequent ergogenic effects of caffeine on performance.
It has been reported that perceptions of exertion are attenuated during prolonged cycle exercise, following CHO ingestion. However, no studies to date have examined the influence of such feedings on psychological affect during prolonged exercise, even though affect and perceived exertion are different constructs.
To examine the influence of regular CHO beverage ingestion on affect (pleasure-displeasure) and perceived exertion during prolonged cycle exercise.
In a randomized, double-blind, counterbalanced design, nine endurance trained males cycled for 2 h at 70% VO2max on two occasions, separated by 1 wk. On each occasion, they consumed either a water placebo (PLA) or a 6.4% carbohydrate-electrolyte solution (CHO) immediately before they cycled (5 mL x kg(-1) body mass) and every 15 min thereafter (2 mL x kg(-1) body mass). Pleasure-displeasure was assessed before, during, and after the prolonged bout of cycling.
During exercise, reported pleasure initially improved and was subsequently maintained in the CHO trial, in contrast to a decline reported in the PLA trial. Ratings of pleasure-displeasure were more positive during recovery in the CHO trial compared with the PLA trial (P < 0.05) and the only significant increase (P < 0.05) in pleasure occurred 15 min postexercise in the CHO trial only. RPE increased (P < 0.05) over the course of the bout of cycling and was lower (P < 0.05) 75 min into exercise in the CHO trial. Immediately postexercise, plasma glucose concentration was higher in the CHO compared with the PLA trial (P < 0.05). A main effect of trial was found for plasma cortisol concentration, with higher values reported in PLA trial.
Results suggest that CHO ingestion enhanced feelings of pleasure during and following prolonged cycling and highlighted the importance of assessing not only "what," but also "how" a person feels.
This double-blind, within-subjects experiment examined the effects of ingesting two doses of caffeine on perceptions of leg muscle pain during moderate-intensity cycling exercise among females.
Low-caffeine-consuming college-aged females (N = 11) ingested one of two doses of caffeine (5 or 10 mg x kg(-1) body weight) or a placebo and 1 h later completed 30 min of cycling on an ergometer at approximately 60% VO2peak. The conditions were completed in a counterbalanced order. Perceptions of leg muscle pain as well as power output, heart rate, systolic blood pressure, and oxygen consumption (VO2) were recorded during exercise.
Caffeine had a significant effect on leg muscle pain ratings [F (2,20) = 10.63, P = 0.001, n2 = 0.52]. The mean pain intensity scores during exercise after ingesting 10 mg x kg(-1) body weight caffeine, 5 mg x kg(-1) body weight caffeine, and placebo were 1.6 +/- 1.1, 1.3 +/- 0.7, and 2.4 +/- 1.1, respectively.
The results support that caffeine ingestion has a large effect on reducing leg muscle pain during exercise among females, but this effect does not appear to be dose-dependent between 5 and 10 mg.kg body weight caffeine.
This study investigated the effect of caffeine ingestion on neutrophil oxidative burst responses to prolonged cycling. In a two part study, 19 endurance trained male cyclists (Part A--11; Part B--8) performed 90 min of exercise at 70% VO2max 1 h after ingesting 6 mg/kg body mass of caffeine (CAF) or placebo (PLA). CAF ingestion had no effect on the PMA-stimulated oxidative burst response (Part A), yet it attenuated the exercise-induced decline in f-MLP stimulated response that occurred with PLA (Part B). CAF ingestion significantly increased serum caffeine concentration and plasma adrenaline concentration following exercise. In addition, circulating lymphocyte count was increased following CAF ingestion whereas there was no effect on neutrophil number. Therefore, although CAF ingestion was associated with an increase in adrenaline, this was not associated with an expected decrease in neutrophil function. This suggests that in the present study, CAF ingestion influenced neutrophil function via alternative mechanisms.
Although both contain behaviourally significant concentrations of caffeine, tea is commonly perceived to be a less stimulating drink than coffee. At least part of the explanation for this may be that theanine, which is present in tea but not coffee, has relaxing effects. There is also some evidence that theanine affects cognitive performance, and it has been found to reduce blood pressure in hypertensive rats.
To study the subjective, behavioural and blood pressure effects of theanine and caffeine administered alone and together, in doses relevant to the daily tea consumption of regular tea drinkers.
In a randomised, double-blind, placebo-controlled study, healthy adult participants (n = 48) received either 250-mg caffeine, 200-mg theanine, both or neither of these. They completed ratings of mood, including anxiety, and alertness, and had their blood pressure measured before and starting 40 min after drug administration. Anxiety was also assessed using a visual probe task.
Caffeine increased self-rated alertness and jitteriness and blood pressure. Theanine antagonised the effect of caffeine on blood pressure but did not significantly affect jitteriness, alertness or other aspects of mood. Theanine also slowed overall reaction time on the visual probe task.
Theanine is a physiologically and behaviourally active compound and, while it is unclear how its effects might explain perceived differences between tea and coffee, evidence suggests that it may be useful for reducing raised blood pressure.
This study was undertaken to examine self-reported caffeine consumption and reasons for its use, amongst UK athletes, following its removal from the 2004 World Anti-Doping Agency (WADA) Prohibited List. A convenience sample of track and field athletes (n = 193) and cyclists (n = 287) completed a postal or Web-based questionnaire. Messages were posted on athletics and cycling club Web sites and mailing lists to direct athletes to the Web-based questionnaire. Postal questionnaires were distributed at domestic sporting events. A higher proportion of cyclists (59.9 %) compared with track and field athletes (32.6 %) consumed caffeine to enhance performance (p < 0.001). A higher proportion of elite as opposed to sub-elite athletes representing cycling (p = 0.031) and athletics (p = 0.010) used caffeine to enhance performance. Of all caffeine containing products used, coffee, energy drinks, pharmaceutical preparations and caffeinated sports supplements were most prevalent. Results revealed that amongst UK athletes, the intention to use caffeine as an ergogenic aid was high, and that use was more widespread and accepted in competitive sport, especially at elite level, when compared to recreational sport.
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Mechanism of action of caffeine
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Time for tea: mood, blood pressure and cognitive performance effects of caffeine and theanine administered alone and together
- P Rogers
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