Guarana (Paullinia cupana) improves anaerobic performance: a randomized, crossover, double-blind, placebo-controlled clinical trial

Introduction Assessing anaerobic performance is essential for monitoring and prescribing sports training. The 30-s continuous jump test (30CJ) is a valid, reliable tool for evaluating anaerobic capacity, particularly in team sports. Among ergogenic aids, anhydrous caffeine is widely utilized, but natural multi-compound matrices like guarana ( Paullinia cupana ) may offer distinct metabolic advantages. Objective To compare the acute effects of equalized doses of guarana and isolated caffeine supplementation on anaerobic performance using the 30CJ test. Materials and methods In a randomized, crossover, double-blind, placebo-controlled design, 18 physically active men (21.8 ± 2.5 years) ingested similar relative caffeine doses (~ 5 mg/kg) via either guarana or anhydrous caffeine capsules, or a matching placebo, 60 min prior to the 30CJ. Maximum jump height (Hmax), mean jump height (Hmean), peak power output (PPO), lowest power output (LPO), fatigue index (FI), and total number of jumps were analyzed across conditions. Results Only guarana supplementation led to a statistically significant increase in PPO compared to placebo (4.0%; d z = 0.82; p = 0.022) and Pre values (4.4%; d z = 0.55; p = 0.041), an effect not statistically replicated by caffeine ( p > 0.05). Although the inferential analysis revealed no significant main effects for Hmax, Hmean, and LPO, descriptive trends uniquely favored guarana over placebo, yielding robust, moderate-to-large pairwise effect sizes ( d z = 0.73, 0.86, and 0.58, respectively) alongside a distinct reduction in total jump volume. Although no active treatments significantly differed from one another, direct descriptive comparisons revealed that guarana consistently outperformed isolated caffeine, showing greater performance values across all measurements, specifically in Hmean (+ 1.5%), PPO (+ 1.4%), Hmax (+ 0.9%), and LPO (+ 0.7%). Conclusion Acute guarana supplementation is effective for enhancing peak anaerobic power during repeated ballistic efforts. While clearing statistical thresholds uniquely in PPO, guarana demonstrates descriptive trends toward greater mechanical efficiency per jump compared to isolated caffeine.