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Caffeine and Placebo Improved Maximal Exercise Performance Despite Unchanged Motor Cortex Activation and Greater Prefrontal Cortex Deoxygenation

Pires, Flavio O.; dos Anjos, Carlos A. S.; Covolan, Roberto J. M.; Fontes, Eduardo B.; Noakes, Timothy D.; St Clair Gibson, Alan; Magalhães, Fernando H.; Ugrinowitsch, Carlos


Flavio O. Pires

Carlos A. S. dos Anjos

Roberto J. M. Covolan

Eduardo B. Fontes

Timothy D. Noakes

Fernando H. Magalhães

Carlos Ugrinowitsch


Caffeine (CAF) is an ergogenic aid used to improve exercise performance. Independent studies have suggested that caffeine may have the ability to increase corticospinal excitability, thereby decreasing the motor cortex activation required to generate a similar motor output. However, CAF has also been suggested to induce a prefrontal cortex (PFC) deoxygenation. Others have suggested that placebo (PLA) may trigger comparable effects to CAF, as independent studies found PLA effects on motor performance, corticospinal excitability, and PFC oxygenation. Thus, we investigated if CAF and CAF-perceived PLA may improve motor performance, despite the likely unchanged MC activation and greater PFC deoxygenation. Nine participants (26.4 ± 4.8 years old, VO2MAX of 42.2 ± 4.6 mL kg-1 min-1) performed three maximal incremental tests (MITs) in control (no supplementation) and ∼60 min after CAF and PLA ingestion. PFC oxygenation (near-infrared spectroscopy at Fp1 position), MC activation (EEG at Cz position) and vastus lateralis and rectus femoris muscle activity (EMG) were measured throughout the tests. Compared to control, CAF and PLA increased rectus femoris muscle EMG (P = 0.030; F = 2.88; d = 0.84) at 100% of the MIT, and enhanced the peak power output (P = 0.006; F = 12.97; d = 1.8) and time to exhaustion (P = 0.007; F = 12.97; d = 1.8). In contrast, CAF and PLA did not change MC activation, but increased the PFC deoxygenation as indicated by the lower O2Hb (P = 0.001; F = 4.68; d = 1.08) and THb concentrations (P = 0.01; F = 1.96; d = 0.7) at 80 and 100% the MIT duration. These results showed that CAF and CAF-perceived PLA had the ability to improve motor performance, despite unchanged MC activation and greater PFC deoxygenation. The effectiveness of CAF as ergogenic aid to improve MIT performance was challenged.


Pires, F. O., dos Anjos, C. A. S., Covolan, R. J. M., Fontes, E. B., Noakes, T. D., St Clair Gibson, A., …Ugrinowitsch, C. (in press). Caffeine and Placebo Improved Maximal Exercise Performance Despite Unchanged Motor Cortex Activation and Greater Prefrontal Cortex Deoxygenation. Frontiers in Physiology, 9, Article 01144.

Journal Article Type Article
Acceptance Date Jul 30, 2018
Online Publication Date Aug 17, 2018
Deposit Date Jan 27, 2021
Publicly Available Date Oct 27, 2022
Journal Frontiers in Physiology
Publisher Frontiers Media
Peer Reviewed Peer Reviewed
Volume 9
Article Number 01144
Keywords Brain regulation; Prefrontal cortex; Performance; Fatigue; VO2MAX
Public URL
Publisher URL


Published article (1.3 Mb)

Copyright Statement
Copyright © 2018 Pires, dos Anjos, Covolan, Fontes, Noakes, St Clair Gibson, Magalhães and Ugrinowitsch. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

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