Efeito Ergogênico da Cafeína e da Expectativa de Eficácia no Desempenho Físico

Abstract

Resistance training (RT) practitioners consume caffeine (CAF) with the expectation of improvement in physical performance. However, the benefits attributed may be more related to the psychological factor than the physiological property of the substance. Thus, the purpose of the study was to verify whether the consumption of (CAF) or the expected outcome would increase the strength and muscular endurance of resistance training practitioners. Eleven subjects (9 men aged 25.43 ± 2.4 years and 7 women aged 25.43 ± 5.61 years) who were physically active, with RT experience (mean 1.8 ± 0.47 years) participated in the study. They completed tests of 1RM and number of repetitions (NMR) in the bench press (SR) and in the machine squat (AM). For this purpose, we use the double-dissociative model that aims to isolate the expectation of results that exist in consuming a certain substance. In order to carry out the tests, all participants were subjected to four conditions, where the expectation was manipulated by the percentage of certainty (0%, 50%, 50% and 100%) of what was being delivered by the researchers. In the 100% condition, it was said that it was CAF and CAF was delivered; in the 50% CAF condition, it was informed that it could be CAF or not, but CAF was delivered; in the other condition, 50% PLA, the same doubt was raised, but a placebo was delivered; and the other condition served as a 0% control, where there was no consumption of capsules. CAF capsules or placebo were consumed 1h before the tests, each containing 345 ± 69.02 mg of CAF per kg of body weight. The results showed that neither the CAF nor the expectation promoted an increase in physical performance in the 1RM tests in the SR and AM did not reach significance (p> 0.41 and p> 0.95). In the NMR test done SR and AM the values of were p> 0.38 and p> 0.45, also did not reach statistical significance. We conclude that the consumption of CAF in order to increase muscle strength or endurance is not justified according to the data presented here in this study.