Effects of caffeinated gum doses combined with post-activation performance enhancement on bench-press bar velocity: a randomized crossover study

Background Evidence from randomized crossover trials indicates that both caffeine and post-activation performance enhancement (PAPE) can independently improve acute performance, but findings on their combined effects remain inconclusive. Therefore, this study examined whether 3 mg/kg or 6 mg/kg of caffeine via gum, when paired with a PAPE conditioning activity, would enhance bench-press bar velocity and total repetitions. Methods Using a randomized, double-blind, placebo-controlled crossover design, 15 male amateur boxers completed six conditions: (a) placebo gum without PAPE (NoPAPE-0); (b)3 mg/kg of caffeine via gum without PAPE (NoPAPE-3); (c) 6 mg/kg of caffeine via gum without PAPE (NoPAPE-6); (d) PAPE + placebo gum (PAPE-0); (e) PAPE + 3 mg/kg of caffeine via gum (PAPE-3), and (f) PAPE + 6 mg/kg of caffeine via gum (PAPE-6). In PAPE conditions, participants performed one set of 3 repetitions of bench press exercise at 90% 1RM. Immediately afterward, participants chewed the assigned gum for 10 min, after which they began the performance test including four 12-s bench-press sets at 60% 1RM, performed at maximal intended velocity with 2-min rests. Mean and peak bar velocity and total repetitions were analyzed with linear mixed models treating with Condition coded as a 2 × 3 factorial (PAPE: No vs. Yes; Dose: 0, 3, 6 mg/kg of caffeine), including planned contrasts for dose effects within PAPE level and for PAPE vs. NoPAPE at matched doses. Results Overall, PAPE produced significant higher mean velocity (+0.018 m/s) and peak velocity (+0.035 m/s) than NoPAPE across all caffeine doses (all p < 0.0001). Independently of PAPE, 3 mg/kg and 6 mg/kg of caffeine significantly improved velocity relative to placebo: mean velocity increased by +0.013–0.015 m/s for 3 mg/kg of caffeine and by +0.017–0.018 m/s for 6 mg/kg of caffeine with no differences between caffeine doses. For total repetitions, PAPE statistically exceeded NoPAPE only under placebo conditions (+2.87 reps; p < 0.0001). Caffeine significantly increased repetitions in NoPAPE (3 mg/kg and 6 mg/kg of caffeine > placebo; both p < 0.0001), but adding caffeine to PAPE did not increase repetition volume. Conclusion Both PAPE and caffeinated gum significantly enhanced bench press bar velocity while combining PAPE with caffeinated gum yields greater performance benefits than caffeinated gum alone, irrespective of dose. In contrast, caffeine alone increased repetition volume, and PAPE did not augment this effect. Practically, athletes seeking to maximize bar velocity may combine PAPE with 3 mg/kg of caffeine via gum, whereas those aiming to increase repetition volume may rely on caffeine alone.