Effects of caffeine on central and peripheral fatigue following closed- and open-loop cycling exercises

Abstract

We 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%, P40.05). 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.

Efeito dose-resposta da utilização oral de cafeína na performance de exercícios aeróbicos: uma revisão sistemática e meta-análise

“…Dentre os exercícios realizados, se identificou uma maior prevalência de testes contrarrelógios de ciclismo (36 artigos [≅73,5%]) (ACKER-HEWITT et al, 2012;ASTORINO et al, 2011;ROUPOLI;VALDIVIESO, 2012a;ASTORINO et al, 2012b;BORTOLOTTI et al, 2014;CONWAY;ORR;STANNARD, 2003;COUTO et al, 2022;COX et al, 2002;DESBROW et al,2009;DESBROW et al, 2012;DEAN;BRAAKHUIS;PATON, 2009;FELIPPE et al, 2018;FERREIRA VIANA et al, 2020;FRANCO-ALVARENGA et al, 2019;GLAISTER et al, 2015;GLAISTER et al, 2021;GONÇALVES et al, 2017;GRAHAM-PAULSON et al,2016;GUEST. et al, 2020;HODGSON;RANDELL;JEUKENDRUP, 2013;IRWIN et al, 2011;JACOBSON et al, 2001;KILDING;OVERTON;GLEAVE, 2012;MORALES et al, 2020;PITCHFORD et al, 2014;POLLOW et al, 2016;POTGIETER;SMITH, 2018;QUINLIVAN et al, 2015;ROELANDS et al, 2011;SANTOS et al, 2013;SANTOS et al, 2020;…”