Corey Grozier, Andrea Bryant, Bandar Alghamdi, Lauren Killen, Hunter Waldman. University of North Alabama, Florence, AL.

BACKGROUND: Caffeine is one of the most examined ergogenic aids over the past 30 years, yet little research has evaluated the placebo effect of caffeine during this time. Furthermore, there is a scarcity of research conducted within the female population. Therefore, the primary aim of this study was to examine the effects of caffeine and the placebo effect in women on markers of anaerobic performance. METHODS: Sixteen females completed five sessions consisting of two familiarization trials and three experimental trials. Prior to the start of the experimental trials, participants were given either a 300 mg form of caffeinated gum or a placebo gum. For the last trial, participants were given a placebo and told they were receiving caffeinated gum. During the experimental trials, participants completed a repeated Wingate protocol consisting of four, 15-s Wingates followed by a 2.5 min recovery. Additionally, heart rate and rating of perceived exertion (RPE) were collected following completion of each Wingate. RESULTS: Wingate variables, RPE, and heart rate were analyzed via a 3x4 repeated measures analysis of variance (RMANOVA). If significant main effects or interaction effects were observed, post hoc testing was performed with Bonferroni’s correction. Additionally, a 1-way RMANOVA was conducted to examine possible changes across resting heart rate in each group. Regarding max power, average power and fatigue index, there were no significant differences found (P>0.05). Regarding RPE, there was not a significant interaction or main effect found (P>0.05), however a significant time effect was found (P<0.001). Specifically, RPE increased across each stage, regardless of supplement. As it relates to heart rate, a significant interaction was not found (P>0.05), however a significant main effect (P=0.02) and a significant time effect (P=0.006) were found. Caffeine increased heart rate compared to either placebo or deception, although no differences between placebo or deception were found for heart rate. Additionally, heart rate increased across each Wingate, regardless of supplement consumed. Moreover, a significant main effect was found for resting heart rate (P=0.02). Caffeine increased resting heart rate compared to the placebo group (P=0.01), but not deception group (P=0.25). Further, deception increased resting heart rate significantly more than the placebo (P=0.03). CONCLUSIONS: Although the deception trial produced no statistical changes regarding performance markers, there was an increase in resting heart rate (~6 bpm) during the deception trial suggesting a psychological component to participants receiving a ‘known’ supplement. Further research is needed however, to determine the exact magnitude of this effect as our study was likely underpowered to observed statistical changes beyond resting heart rate.

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