Tyler N. Talik1, Mindy Millard-Stafford, FACSM1, Brian Hack1, Alec Harp1, Eduardo Macedo Penna2. 1Georgia Institute of Technology, Atlanta, GA. 2Federal University of Pará, Belem.

BACKGROUND: Effects of guarana (Paullinia cupana) seed extract, a Brazilian plant containing caffeine but with additional bioactive compounds, has been observed to potentially improve cognitive performance and mood, particularly under fatiguing conditions. Our purpose was to assess the effects of acute ingestion of guarana (GUA) compared to a matched dose of caffeine (CAF) on cognitive function and mood in endurance athletes before and after high-intensity exercise. METHODS: Eleven endurance-trained athletes (age: 20 ± 4.7 y, height: 180.2 ± 7.2 cm, body mass: 73.9 ± 8.8 kg, V̇O2max: 54.6 ± 7.8 ml/kg/min) participated in a randomized, double-blind, crossover experiment. All subjects completed three trials ingesting capsules containing: 1) 100 mg CAF, 2) 100 mg GUA or 3) placebo (P). Cognitive and mood tests were performed at baseline (pre-ingestion), 60 min post-ingestion of capsules, then again after cycling (60-min steady state at ~70% V̇O2max [SS] + 15-min maximal effort time trial). Accuracy (% correct responses) and reaction time (RT) were recorded on Simon Task (interference/conflict resolution) and N-Back Task (working memory) followed by NASA Task Load (mental workload) and Brunel Mood Scales (fatigue and other subscales). RESULTS: Accuracy was not affected (p > 0.05) by capsule treatment or time (pre-versus post-ingestion or post-exercise) for both cognitive tests. RT was only affected (p = 0.03) by time: faster post-exercise compared to pre-ingestion on the N-Back test. Neither capsule treatment nor time of measurement influenced (p > 0.05) mental workload or mood subscales. During the last 10 min of SS, there was a significant interaction effect (p = 0.042) for ratings of perceived exertion (Borg Scale): ratings were lower for GUA (14.0 ± 1.0) versus CAF (15.0 ± 1.0) and tended to be lower than P (14.8 ± 1.4). CONCLUSION: Neither guarana nor a matched dose of caffeine influenced cognitive performance or mood before or after fatiguing exercise. However, guarana appeared to reduce the perceived effort for endurance-trained athletes toward the late stage of moderate-to-vigorous intensity exercise. These findings merit additional investigation to determine whether acute guarana ingestion can attenuate fatigue in different populations (clinical, sedentary, athletic individuals). Supported in part by the Fulbright Scholar Fellowship Program

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