Caffeine potentiates low frequency skeletal muscle force in habitual and nonhabitual caffeine consumers

Tarnopolsky, Mark A.; Cupido, Cynthia

doi:10.1152/jappl.2000.89.5.1719

Cited by 171 publications

(184 citation statements)

References 33 publications

(57 reference statements)

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“…However, the positive effect of caffeine on endurance and fatigue is well demonstrated in a large number of studies [5,[9][10][11][12][13]. It is not clear if this positive effect is related to a more effective muscular contraction.…”

Section: Musclementioning

confidence: 99%

Electrophysiological Studies in Healthy Subjects Involving Caffeine

Carvalho

Marcelino

2010

JAD

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Abstract. We review the electrophysiological studies concerning the effects of caffeine on muscle, lower and upper motor neuron excitability and cognition. Several different methods have been used, such as electromyography, recruitment analysis, H-reflex, transcranial magnetic stimulation (TMS), electroencephalography and event-related potentials. The positive effect of caffeine on vigilance, attention, speed of reaction, information processing and arousal is supported by a number of electrophysiological studies. The evidence in favor of an increased muscle fiber resistance is not definitive, but higher or lower motor neuron excitability can occur as a consequence of a greater excitation of the descending input from the brainstem and upper motor neurons. TMS can address the influence of caffeine on the upper motor neuron. Previous studies showed that cortico-motor threshold and intracortical excitatory and inhibitory pathways are not influenced by caffeine. Nonetheless, our results indicate that cortical silent period (CSP) is reduced in resting muscles after caffeine consumption, when stimulating the motor cortex with intensities slightly above threshold. We present new data demonstrating that this effect is also observed in fatigued muscle. We conclude that CSP can be considered a surrogate marker of the effect of caffeine in the brain, in particular of its central ergogenic effect.

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Section: Musclementioning

confidence: 99%

Electrophysiological Studies in Healthy Subjects Involving Caffeine

Carvalho

Marcelino

2010

JAD

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“…All subjects were asked to refrain from intense or unaccustomed exercise 24 hours before testing and to remain relatively inactive for the total duration of testing. In addition, subjects were asked to abstain from caffeine on testing days as it has been shown to affect muscular force at low activation frequencies (34).…”

Section: Subjectsmentioning

confidence: 99%

Low-Frequency Fatigue in Individuals With Spinal Cord Injury

Mahoney

Puetz

Dudley

et al. 2007

The Journal of Spinal Cord Medicine

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Background/Objective: This study examined magnitude and recovery of low-frequency fatigue (LFF) in the quadriceps after electrically stimulated contractions in spinal cord-injured (SCI) and able-bodied subjects.Subjects: Nine SCI (ASIA A-C, levels C5-T9, injured 13.6 6 12.2 years) and 9 sedentary able-bodied subjects completed this study.Methods: Fatigue was evoked in 1 thigh, and the nonfatigued leg served as a control. The fatigue test for able-bodied subjects lasted 15 minutes. For SCI, stimulation was adjusted so that the relative drop in force was matched to the able-bodied group. Force was assessed at 20 (P20) and 100 Hz (P100), and the ratio of P20/P100 was used to evaluate LFF in thighs immediately after, at 10, 20, and 60 minutes, and at 2, 4, 6, and 24 hours after a fatigue test.Results: The magnitude of LFF (up to 1 hour after fatigue) was not different between able-bodied and patients with SCI. However, recovery of LFF over 24 hours was greater in able-bodied compared with patients with SCI in both the experimental (P , 0.001) and control legs (P , 0.001). The able-bodied group showed a gradual recovery of LFF over time in the experimental leg, whereas the SCI group did not. Conclusions:These results show that individuals with SCI are more susceptible to LFF than able-bodied subjects. In SCI, simply assessing LFF produced considerable LFF and accounted for a substantial portion of the response. We propose that muscle injury is causing the dramatic LFF in SCI, and future studies are needed to test whether ''fatigue'' in SCI is actually confounded by the effects of muscle injury.

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“…However, the main pharmacological effects of caffeine appear to be mediated via the CNS where caffeine counterbalances the inhibitory neuromodulation of adenosine in order to induce effects on both the CNS and peripheral nervous system to reduce pain and exertion perception [21], to improve motor recruitment [22] and to increase excitation-contraction coupling [23,24].…”

mentioning

confidence: 99%

Potential pitfalls when investigating the ergogenic effects of caffeine in mice

Solano¹,

Scheffer²,

Alves³

et al. 2017

J Syst Integr Neurosci

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Caffeine (1,3,7-trimethylxantine) is the most commonly consumed social drug in western society for increased physical and cognitive performance [1][2][3][4][5], and it is the main ergogenic resource used by athletes [6]. Initially controversial, caffeine was banned by the International Olympic Committee from 1980-2003 [1,6,7], but then in 2004 its use was approved by the World Anti-doping Agency (WADA), and later this year by the U.S. Anti-doping Agency (USADA; 2016). However, caffeine has remained on the lists of monitored substances of these anti-doping agencies. Caffeine is rapidly and completely absorbed by the gastrointestinal tract and is readily distributed throughout all tissues of the body, including muscles and the central nervous system (CNS), which are believed to be the main recipients of caffeine's ergogenic effects [2,14]. Ergogenic doses of caffeine ranging from 3 to 9 mg/kg body mass [6] appear to have no adverse effects. A moderate oral dose of 6 mg/ kg body mass, which elicits peak plasma levels of about 60 µmol/L concentrations after 30 to 60 min, with half-life for elimination range between 2.5-10 h, is known to enhance physical and cognitive performance [5,6,10,14,15]. Blood levels of 1 -2 mmol/L are known to be toxic and even lethal [14], and have been associated with suicides [16]. Caffeine's molecular mechanisms for increasing physical performance are still virtually undefined. However, due to its ability to cross the blood-brain barrier at blood concentrations generated by a moderate ergogenic dose, and because of its properties as a stimulant psychotropic drug [15,17], mechanisms involving metabolic and central effects have been proposed.Metabolic effects of caffeine have been mainly related to the enhancement of lipolysis, fatty acid oxidation and energy expenditure via the stimulation of the sympathetic nervous system [18,19] and a sequential sparing of muscle glycogen [20]. However, the main pharmacological effects of caffeine appear to be mediated via the CNS where caffeine counterbalances the inhibitory neuromodulation of adenosine in order to induce effects on both the CNS and peripheral nervous system to reduce pain and exertion perception [21], to improve motor recruitment [22] and to increase excitation-contraction coupling [23,24].Caffeine is a non-selective competitive adenosine receptor antagonist (A 1 R and A 2 AR subtypes) that increases neurotransmission via dopamine D 2 receptors (D 2 R) [25,26]. The striatum expresses high levels of A 2 AR where they are co-expressed with postsynaptic D 2 R, forming A 2 AR-D 2 R heterodimers [25]. In this scenario, caffeine fails to be ergogenic in the mouse lacking A 2 AR [27], or in wild type rats treated with the selective A 2 AR agonist 5'-N-ethylcarboxamidoadenosine (NECA) [26], which denotes the participation of these receptors in caffeine's central-mediated ergogenic effects.When designing experimental models to better define the molecular mechanisms involved in the enhanced capacity of caffeine to positively modulate physical ...

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Caffeine potentiates low frequency skeletal muscle force in habitual and nonhabitual caffeine consumers

Cited by 171 publications

References 33 publications

Electrophysiological Studies in Healthy Subjects Involving Caffeine

Electrophysiological Studies in Healthy Subjects Involving Caffeine

Low-Frequency Fatigue in Individuals With Spinal Cord Injury

Potential pitfalls when investigating the ergogenic effects of caffeine in mice

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