Dose-response effects of caffeine during an intermittent protocol of specific skills in soccer players: a double‑blind, placebo‑controlled, crossover study

Given the discrepancies in the existing literature, it is important to investigate the dose–response effects of caffeine during intermittent efforts involving changes of direction. Therefore, this study aimed to examine the acute effects of different doses of caffeine (2, 4, and 6 mg·kg⁻¹) on performance during an intermittent protocol of soccer-specific skills. Eleven male amateur soccer players completed four experimental sessions under the following conditions: placebo, 2, 4, and 6 mg·kg⁻¹ of caffeine, using a randomized, double-blind, placebo-controlled, crossover design. Participants performed four intermittent bouts of the Loughborough Soccer Passing Test (LSPT). Rating of perceived exertion (RPE) was recorded before and after each session. There was no main effect of condition on the sum of movement time (p = 0.48), sum of penalty time (p = 0.61), or sum of total performance time (p = 0.49). Caffeine supplementation at any of the tested doses did not enhance intermittent soccer-specific skills performance in amateur players.