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The purpose of the present study was to investigate the effects of caffeine ingestion on pacing strategy and energy expenditure during a 4000-m cycling time-trial TT. Eight recreationally-trained male cyclists volunteered and performed a maximal incremental test and a familiarization test on their first and second visits, respectively. On the third and fourth visits, the participants performed a 4000-m cycling TT after ingesting capsules containing either caffeine 5 mg.kg−1 of body weight, CAF or cellulose PLA. The tests were applied in a double-blind, randomized, repeated-measures, cross-over design. When compared to PLA, CAF ingestion increased mean power output 219.1±18.6 vs. 232.8±21.4 W; effect size ES  = 0.60 95% CI = 0.05 to 1.16, p = 0.034 and reduced the total time 419±13 vs. 409±12 s; ES = −0.71 95% CI = −0.09 to −1.13, p = 0.026. Furthermore, anaerobic contribution during the 2200-, 2400-, and 2600-m intervals was significantly greater in CAF than in PLA p<0.05. However, the mean anaerobic 64.9±20.1 vs. 57.3±17.5 W and aerobic 167.9±4.3 vs. 161.8±11.2 W contributions were similar between conditions p>0.05. Similarly, there were no significant differences between CAF and PLA for anaerobic work 26363±7361 vs. 23888±6795 J, aerobic work 68709±2118 vs. 67739±3912 J, or total work 95245±8593 vs. 91789±7709 J, respectively. There was no difference for integrated electromyography, blood lactate concentration, heart rate, and ratings of perceived exertion between the conditions. These results suggest that caffeine increases the anaerobic contribution in the middle of the time trial, resulting in enhanced overall performance.



Autor: Ralmony de Alcantara Santos, Maria Augusta Peduti Dal Molin Kiss, Marcos David Silva-Cavalcante, Carlos Rafaell Correia-Oliveira,

Fuente: http://plos.srce.hr/



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