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Purpose: To compare the acute effects of caffeine and placebo ingestion with a control condition (ie, no supplementation) on vertical jump performance., Methods: The sample for this study consisted of 26 recreationally trained men. Following the familiarization visit, the subjects were randomized in a double-blind manner to 3 main conditions: placebo, caffeine, and control. Caffeine was administered in the form of a gelatin capsule in the dose of 6 mg·kg body weight-1. Placebo was also administered in the form of a gelatin capsule containing 6 mg·kg-1 of dextrose. Vertical jump performance was assessed using a countermovement jump performed on a force platform. Analyzed outcomes were vertical jump height and maximal power output., Results: For vertical jump height, significant differences were observed between placebo and control conditions (g = 0.13; 95% confidence interval [CI], 0.03-0.24; +2.5%), caffeine and control conditions (g = 0.31; 95% CI, 0.17-0.50; +6.6%), and caffeine and placebo conditions (g = 0.19; 95% CI, 0.06-0.34; +4.0%). For maximal power output, no significant main effect of condition (P = .638) was found., Conclusions: Ingesting a placebo or caffeine may enhance countermovement jump performance compared with the control condition, with the effects of caffeine versus control appearing to be greater than the effects of placebo versus control. In addition, caffeine was ergogenic for countermovement jump height compared with placebo. Even though caffeine and placebo ingestion improved vertical jump height, no significant effects of condition were found on maximal power output generated during takeoff.

We aimed to explore the effects of caffeinated gel ingestion on neuromuscular performance in resistance-trained men. The participants ( n = 17; mean ± standard deviation (SD): age 23 ± 2 years, height 183 ± 5 cm, body mass 83 ± 11 kg) completed two testing conditions that involved ingesting a caffeinated gel (300 mg of caffeine) or placebo. The testing outcomes included: (1) vertical jump height in the squat jump (SJ) and countermovement jump (CMJ); (2) knee extension and flexion peak torque and average power at angular velocities of 60°·s -1 and 180°·s -1 ; (3) barbell velocity in the bench press with loads corresponding to 50%, 75%, and 90% of one-repetition maximum (1RM); and (4) peak power output in a test on a rowing ergometer. Compared to the placebo, caffeine improved: (1) SJ ( p = 0.039; Cohen's d effect size ( d ) = 0.18; +2.9%) and CMJ height ( p = 0.011; d = 0.18; +3.3%); (2) peak torque and average power in the knee extensors at both angular velocities ( d ranged from 0.21 to 0.37; percent change from +3.5% to +6.9%), peak torque ( p = 0.034; d = 0.24; +4.6%), and average power ( p = 0.015; d = 0.32; +6.7%) at 60°·s -1 in the knee flexors; (3) barbell velocity at 50% 1RM ( p = 0.021; d = 0.33; +3.5%), 75% 1RM ( p < 0.001; d = 0.42; +5.4%), and 90% 1RM ( p < 0.001; d = 0.59, +12.0%). We conclude that the ingestion of caffeinated gels may acutely improve vertical jump performance, strength, and power in resistance-trained men.