Plain language summary
Caffeine is a widely used supplement in competitive sports, and numerous studies have examined the acute performance-enhancing effects of caffeine intake. The aim of this randomised, crossover, double-blind study was to assess the acute effects of various doses of caffeine on power output in 15 athletes habitually consuming caffeine. Participants performed four different experimental sessions with a one-week washout period between sessions. Power output was assessed through a bench press exercise under the four different conditions of placebo, low-dose caffeine (3mg/kg/b.m.), mid-dose caffeine (6mg/kg/b.m.) and high-dose caffeine (9mg/kg/b.m.). This study found that in habitual caffeine consumers, there was no statistically significant difference in acute power output during the bench press exercise between any of the conditions. Based on these results, the authors suggest other forms of exercise and intensities of exercise should be considered in the future.
Abstract
BACKGROUND Previously studies confirm ergogenic effects of caffeine (CAF); however there is no available scientific data regarding the influence of acute CAF intake on power output in athletes habitually consuming CAF. The main goal of this study was to assess the acute effect of 3, 6, 9 mg/kg/b.m. doses of CAF intake on power output and bench press bar velocity in athletes habitually consuming CAF. METHODS The study included 15 healthy strength-trained male athletes (age = 26.8 ± 6.2 years, body mass = 82.6 ± 9.7 kg; BMI = 24.8 ± 2.7; bench press 1RM = 122.3 ± 24.5 kg). All participants were habitual caffeine consumers (5.2 ± 1.2 mg/kg/b.m.; 426 ± 102 mg of caffeine per day). This study had a randomized, crossover, double-blind study design where each participant performed four different experimental sessions, with one week interval between each trial. In every experimental session participants performed bench press, three sets of five repetitions at 50% 1RM. The power output and bar velocity assessments under four different conditions: a placebo (PLAC), and three doses of caffeine ingestion: 3 mg/kg/b.m. (CAF-3), 6 mg/kg/b.m. (CAF-6) and 9 mg/kg/b.m. (CAF-9). RESULTS The statistical significance was set at p < 0.05. The repeated measures ANOVA between PLAC and CAF-3; CAF-6; CAF-9 revealed no statistically significant differences in power output and velocity of the bar during the bench press exercise. A large effect size (ES) in mean power-output was found between PLAC and CAF-9 in Sets 1 and 2. A large ES in peak power-output was found between PLAC and CAF-6 in Set 2, and between PLAC and CAF-9 in Sets 1 and 2. A large ES in peak velocity was found between PLAC and CAF-9 in Sets 1-3. CONCLUSION The results of the present study indicate that acute doses of CAF before exercise does not have a significant effect on power output and bar velocity in a group of habitual caffeine users.
Methodological quality
Jadad score
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3
Allocation concealment
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Not applicable
