Couto, P. G.Silva-Cavalcante, M. D.Mezêncio, B.Azevedo, R. A.Cruz, R.Bertuzzi, R.Lima-Silva, A. E.Kiss, M. A. P. D.2024-08-132024-08-132022-02-28COUTO, P.G. et al. Effects of caffeine on central and peripheral fatigue following closed- and open-loop cycling exercises. Brazilian Journal of Medical and Biological Research, Ribeirão Preto, v. 55, e11901, 28 feb. 2022.1414-431Xhttps://doi.org/10.1590/1414-431X2021e11901http://www.sbicafe.ufv.br/handle/123456789/14533We examined whether endurance performance and neuromuscular fatigue would be affected by caffeine ingestion during closed- and open-loop exercises. Nine cyclists performed a closed-loop (4,000-m cycling time trial) and an open-loop exercise (work rate fixed at mean power of the closed-loop trial) 60 min after ingesting caffeine (CAF, 5 mg/kg) or placebo (PLA, cellulose). Central and peripheral fatigue was quantified via pre- to post-exercise decrease in quadriceps voluntary activation and potentiated twitch force, respectively. Test sensitivity for detecting caffeine-induced improvements in exercise performance was calculated as the mean change in time divided by the error of measurement. Caffeine ingestion reduced the time of the closed-loop trial (PLA: 375.1±14.5 s vs CAF: 368.2±14.9 s, P=0.024) and increased exercise tolerance during the open-loop trial (PLA: 418.2±99.5 s vs CAF: 552.5±106.5 s, P=0.001), with similar calculated sensitivity indices (1.5, 90%CI: 0.7-2.9 vs 2.8, 90%CI: 1.9-5.1). The reduction in voluntary activation was more pronounced (P=0.019) in open- (-6.8±8.3%) than in closed-loop exercises (-1.9±4.4%), but there was no difference between open- and closed-loop exercises for the potentiated twitch force reduction (-25.6±12.8 vs -26.6±12.0%, P>0.05). Caffeine had no effect on central and peripheral fatigue development in either mode of exercise. In conclusion, caffeine improved endurance performance in both modes of exercise without influence on post-exercise central and peripheral fatigue, with the open-loop exercise imposing a greater challenge to central fatigue tolerance.pdfenOpen accessOpen AccessEndurance performance;Neuromuscular fatigueCentral fatiguePeripheral fatigueErgogenic aidCafeicultura::Café e saúdeArtigo