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

Autor(es)

Pires, Flavio O. ^[1] ; dos Anjos, Carlos A. S. ^[2] ; Covolan, Roberto J. M. ^[2] ; Fontes, Eduardo B. ^[3] ; Noakes, Timothy D. ^[4] ; Gibson, Alan St Clair ; Magalhaes, Fernando H. ^[1] ; Ugrinowitsch, Carlos ^[5]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Sch Arts Sci & Humanities, Exercise Psychophysiol Res Grp, Sao Paulo - Brazil

^[2] Univ Estadual Campinas, Gleb Wataghin Phys Inst, Neurophys Grp, Campinas, SP - Brazil

^[3] Univ Fed Rio Grande do Norte, Res Grp Phys Act Cognit & Behav, Natal, RN - Brazil

^[4] Univ Cape Town, Sports Sci Inst South Africa, Dept Human Biol, Cape Town - South Africa

^[5] Univ Sao Paulo, Sch Phys Educ & Sport, Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: FRONTIERS IN PHYSIOLOGY; v. 9, AUG 17 2018.
• Citações Web of Science: 7

Resumo

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, VO(2MAX )of 42.2 +/- 4.6 mL kg(-1) min(-1)) performed three maximal incremental tests (MITs) in control (no supplementation) and similar to 60 min after CAF and PLA ingestion. PFC oxygenation (near-infrared spectroscopy at Fpl 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 O(2)Hb (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. (AU)

• Processo FAPESP: 16/16496-3 - Efeitos do bochecho de carboidrato sobre o desempenho físico e respostas psicofisiológicas de indivíduos mentalmente fadigados durante teste de VO2MÁX
• Beneficiário: Flávio de Oliveira Pires
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 15/13096-1 - Adaptações neuromusculares associadas à prática esportiva: efeito da fadiga muscular sobre parâmetros eletromiográficos e sobre o controle postural
• Beneficiário: Fernando Henrique Magalhães
• Modalidade de apoio: Auxílio à Pesquisa - Regular