Efeito de diferentes doses da suplementação de teacrina sobre o desempenho em uma prova contrarrelógio de ciclismo de 4 Km

Abstract

There are currently many supplements that promise an improvement in exercise performance. One of them is Theacrine (1,3,7,9-tetramethyluric acid), which has been recently studied as a promising supplement to improve sport performance. The aim of the present study was to verify the effects of different doses of theacrine on performance during a 4-km cycling time trial. Thus, 19 recreationally trained cyclists (11 men and 8 women; Age: 30.8 ± 10.0 years; Weight: 71.7 ± 11.8 kg; Height: 170.1 ± 9.0 cm; body fat percentage: 17.0 ± 6.2 %) were invited to complete five visits to the laboratory, with a minimum interval of 48 hours between the visits. The first visit consisted of an anthropometric assessment, followed by an incremental test and a 4- km cycling time trial for familiarization with the procedures. On the second visit, two more familiarization sessions with experimental procedures were performed. On the third, fourth and fifth visits, in a counterbalanced, randomized, and double-blind manner, 4-km time trials were performed after ingesting theacrine 3 mg/kg (TEA 3), theacrine 6 mg/kg (TEA 6) or placebo (PLA); the participants were instructed to complete the trial as fast as possible and were free to adopt their own pacing strategy. Pre-test (two hours after supplementation) heart rate (HR), motivation to perform the task, and perception of tiredness were not different between conditions (p > 0.05). However, pre-test systolic blood pressure (SBP) and diastolic blood pressure (DPB) were lower in the PLA than in the TEA 6 condition (p < 0.05). An interaction effect was found for power output (p < 0.05); however, the post-hoc analysis did not locate where the differences were, demonstrating only a borderline effect for the first 100 m, in which the power output tended to be greater in the TEA 6 than in TEA 3 (p = 0.07). There was also an interaction effect for HR (p < 0.05), where values at 100 m of the TEA 6 were lower than in the PLA condition (p = 0.01). However, no significant differences were found for performance time between the conditions (PLA: 403.3 ± 24.2 s; TEA 3: 403.5 ± 27.9 s; TEA 6: 401.1 ± 24.6 s). In conclusion, theacrine supplementation at different doses (3 and 6 mg/kg) does not seem to improve 4 km cycling time trial performance, and has marginal effect in some physiological parameters.