Berjisian, Efran ORCID: 0000-0003-3077-3605, Naderi, Alireza ORCID: 0000-0002-8539-4306, Mojtahedi, Shima, Grgic, Jozo ORCID: 0000-0002-6929-2844, Ghahramani, Mohammad Hossein, Karayigit, Raci ORCID: 0000-0001-9058-1918, Forbes, Jennifer L, Amaro-Gahete, Francisco J ORCID: 0000-0002-7207-9016 and Forbes, Scott C ORCID: 0000-0001-6896-5552 (2022) Are caffeine’s effects on resistance exercise and jumping performance moderated by training status? Nutrients, 14 (22). ISSN 2072-6643

Abstract

This study aimed to explore if the effects of caffeine intake on resistance exercise and jumping performance are moderated by training status. We included ten resistance-trained and ten recreationally active males in a randomized, double-blind, crossover study. Participants were categorized into groups according to their resistance to training experience and muscular strength levels. Exercise performance outcomes included weight lifted and mean velocity during a one-repetition maximum (1RM) bench press and squat; repetitions were performed to muscular failure in the same exercises with 70% of 1RM and countermovement jump (CMJ) height. Exercise performance was evaluated on three occasions, following no substance ingestion (control), caffeine (6 mg/kg), and placebo. There was a main effect on the condition for all the performance outcomes (all p ≤ 0.02), except for the 1RM squat mean velocity (p = 0.157) and 1RM bench press mean velocity (p = 0.719). For weight lifted in the 1RM bench press, there was a significant difference when comparing the caffeine vs. control, caffeine vs. placebo, and placebo vs. control. For weight lifted in the 1RM squat, a significant difference was found when comparing the caffeine vs. control. For muscular endurance outcomes and jump height, a significant difference was found when caffeine was compared to the control or placebo. Effect sizes were trivial for muscular strength (Hedges’ g: 0.04–0.12), small for the jump height (Hedges’ g: 0.43–0.46), and large for muscular endurance (Hedges’ g: 0.89–1.41). Despite these ergogenic effects, there was no significant training status × caffeine interaction in any of the analyzed outcomes. In summary, caffeine ingestion is ergogenic for muscular strength, endurance, and jump height. These effects are likely to be of a similar magnitude in resistance-trained and recreationally active men.

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