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Effects of Caffeine Ingestion on Pulmonary V˙O2 Kinetics and Muscle Fatigue During Severe-Intensity Cycling Exercise
Rafael Leal Dantas Estrela1,2, Jean de Souza Dos Santos1, Paulo Cesar do Nascimento Salvador1
1Physical Effort Laboratory, Department of Physical Education, Sports Center, Federal University of Santa Catarina (UFSC), Florianopolis, Brazil.
Introduction:
This study aimed to analyze the effect of caffeine (CAF) intake on pulmonary oxygen uptake (V˙O2) kinetics, muscle fatigue, and physiological and perceptual parameters during severe-intensity cycling exercise.
Methods:
Twelve physically active men (age: 26 ± 5 years; V˙O2peak: 46.7 ± 7.8 ml·kg-1·min-1) participated of this placebo (PLA)-controlled, randomized, double-blinded, and crossover design study. Participants performed on separate days (a) a ramp incremental test to determine V˙O2peak and gas exchange threshold and (b) four 8-min constant work rate tests at 60% of the difference between gas exchange threshold and maximal V˙O2peak (i.e., Δ60%) 1 hr after taking either 6 mg/kg of body mass of CAF or PLA. Before and immediately after constant work rate tests, a 5-s all-out isokinetic sprint was performed to assess the muscle torque. V˙O2 kinetics, blood lactate concentration ([La]), and rating of perceived exertion were analyzed during constant work rate tests.
Results:
CAF did not alter the primary time constant of V˙O2 kinetics (PLA: 38.3 ± 14; CAF: 36.7 ± 7.5 s), V˙O2 slow component (PLA: 0.5 ± 0.2; CAF: 0.5 ± 0.2 L/min), or peak torque (PLA: 144.6 ± 18.6; CAF: 143.9 ± 18.7 N·m). CAF decreased rating of perceived exertion (15.9 ± 1.8 vs. 17.0 ± 1.5 a.u.) and increased blood lactate concentration (9.0 ± 2.5 vs. 8.3 ± 2.2 mmol/L; p < .05) after constant work rate tests compared with PLA.
Conclusion:
CAF ingestion does not alter V˙O2 kinetics or muscle torque production during 8 min of severe-intensity cycling exercise.
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