The effects of acute caffeine supplementation on performance in trained CrossFit® athletes: A randomized, double-blind, placebo-controlled, and crossover trial

Objectives. - The present study aimed to evaluate the effects of caffeine on muscle strength, using a test involving one maximum repetition of the back squat, as well as on local muscular endurance. Equipment and methods. - Eight trained men (mean age = 30.1 +/- 6.5 years; height = 1.79 +/- 0.07 meters; body mass = 81.5 +/- 7.7 kg) were included in a double-blind, randomized, crossover study. The participants consumed caffeine (6 mg.kg(-1)) or placebo (cellulose) 60 minutes before starting the tests, with one week of washout. The participants underwent the one maximum repetition back squat test. Subsequently, they were instructed to perform the maximum number of repetitions with 60% of the maximum load to test local muscular endurance. Shapiro-Wilk and paired t-test were performed. Results. - Local muscular endurance score was higher for the caffeine group compared to placebo (3515.0 + 1073.1 vs. 2846.5 + 768.0 kg, P = 0.029) but not in the one maximum rep-etition test (156.6 + 26.2 vs. 153.9 + 29.5 kg, P = 0.224). The average number of repetitions were higher in the caffeine group (37.8 + 11.1 vs. 31.4 + 9.3 repetitions, P = 0.033). Caffeine had an ergogenic effect on CrossFit (R) athletes in terms of the number of repetitions, mainly when a more aerobic component (local muscular endurance) was involved; however, no effects were observed in the one maximum repetition test. (c) 2023 Elsevier Masson SAS. All rights reserved.