CAFFEINE IMPROVES ENDURANCE PERFORMANCE
Desbrow, B., Irwin, C., Ellis, A., O'Keefe, B., Grant, G., & Leveritt, M. (2010). Caffeine withdrawal and high intensity endurance cycling performance. Presentation 924 at the 2010 Annual Meeting of the American College of Sports Medicine, Baltimore, Maryland; June 2-5.
This study investigated the impact of a controlled four-day caffeine withdrawal period on the effect of an acute caffeine dose on endurance exercise performance. Trained and familiarized male cyclists (N = 12) who were regular caffeine consumers, participated. A double-blind placebo-controlled cross-over design was employed in which all subjects participated in four experimental trials. For four days prior to all trials, Ss abstained from dietary caffeine sources and ingested capsules containing either placebo or caffeine (1.5 mg/kg). Ss then ingested capsules containing placebo or caffeine (3 mg/kg) 90 minutes prior to completing a time-trial, equivalent to one hour cycling at 75% peak sustainable power output.
Performance time improved significantly after acute caffeine ingestion by ~3.0% following a withdrawal period and ~3.6% following the non-withdrawal period. No significant difference was detected between the two acute caffeine trials. Average heart rate throughout exercise was significantly higher following acute caffeine administration compared to placebo. No differences were observed in ratings of perceived exertion between trials.
Implication. Caffeine (~3 mg/kg) significantly improves endurance exercise performance irrespective of whether or not a four-day withdrawal period is imposed on habitual caffeine users.
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