Abstract
Background: Caffeine has been used by some athletes to improve short-term high-intensity exercise performance; however, the literature is equivocal. Objectives: The objective of this study was to investigate the effects of caffeine on plasma potassium and catecholamine concentrations, pain and fatigue perception, to determine whether potassium ion handling and altered perception related to the central nervous system are associated with enhanced performance during a 1 km cycling time trial. Methods: Thirteen well trained men with a mean age of 27 ± 6 yrs (body mass: 76.4 ± 6.4 kg, height: 180 ± 7 cm, and max: 57.5 ± 4.6 ml·kg -1 ·min -1 ) were recruited. Participants were randomized to a caffeine (5 mg·kg -1 ) or a placebo condition using a double blind, cross over design. Results: Caffeine had no significant effects on the 1 km time-trial performance indicators of time (82.1 ± 2.4 vs. 81.9 ± 3.9s), peak (633.0 ± 83.6 vs. 638.7 ± 110.1 watts) or average power (466.0 ± 37.3 vs. 467.5 ± 59.9 watts; caffeine and placebo conditions respectively). In addition, caffeine had no significant effect on oxygen consumption () (4.11 ± 0.24 vs 4.06 ± 0.29 L),the perception of pain (5.6 ± 2.4 vs. 5.5 ± 2.6) or fatigue (7.1 ± 1.8 vs.7.1 ± 1.8: caffeine and placebo conditions respectively). There was a significantly greater increase in post-exercise blood lactate (p<0.05) and catecholamines (p<0.05) as well as a lower pre-exercise blood potassium concentration (p<0.05) in the caffeine condition. Conclusions: The results suggest that caffeine can enhance certain metabolic parameters, but these changes were unable to augment short-distance (1km), high-intensity cycling performance. Keywords: ergogenic, anaerobic exercise, performance, oxygen consumption
Highlights
1.1 Review of LiteratureCaffeine has been used as a supplement to improve exercise performance of various durations and intensities
The purpose of this study was to investigate the effects of caffeine on pain and fatigue perception, plasma catecholamine and potassium concentrations to determine whether altered central nervous system perception and/or potassium ion handling were associated with any changes in performance during a 1 km cycling time trial in trained cyclists
Blood lactate concentrations were significantly increased post exercise in both the caffeine and placebo condition when compared to pre-1 km cycling time-trial concentrations
Summary
1.1 Review of LiteratureCaffeine has been used as a supplement to improve exercise performance of various durations and intensities. Little research has investigated the effects of caffeine on plasma potassium levels after short-term high-intensity exercise (Davis & Green, 2009). Caffeine influences the central nervous system via an increase in catecholamines (Berkowitz et al, 1970) that were greater during high intensity anaerobic exercise compared to placebo (Bell et al, 2001; Doherty et al, 2002; Greer et al, 1998). Objectives: The objective of this study was to investigate the effects of caffeine on plasma potassium and catecholamine concentrations, pain and fatigue perception, to determine whether potassium ion handling and altered perception related to the central nervous system are associated with enhanced performance during a 1 kg, km cycling height: 180 time ± 7 ctrmia,l.anMd eV thOod sm: aTxh:ir5t7ee.5n well trained men with a mean age of ± 4.6 ml·kg-1·min-1) were recruited. There was a significantly greater increase in post-exercise blood lactate (p
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