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.

Background: Intermittent fasting (IF) can improve inflammatory status, but its effects may be dependent on the mode of fasting. Objectives: We performed a systematic review with pairwise and network meta-analyses to investigate the effects of different modes of IF on inflammatory markers in adults. Methods: Three database searches were conducted, including PubMed, Scopus, and Web of Science, from inception to June 2024. The searches used two keyword groups: “intermittent fasting” and “inflammatory markers”. Randomized and non-randomized trials investigating any IF mode on inflammatory markers, including interleukin (IL)-6, tumor necrosis factor (TNF)α, C-reactive protein (CRP), leptin, and adiponectin, were included. Standardized mean differences (SMDs) were calculated using random effects models for both analyses. Results: A total of 21 studies (839 participants) were included. Compared with controls, IF reduced TNF-α [SMD: −0.31, p = 0.009], CRP [SMD: −0.19, p = 0.04], and leptin [SMD: −0.57, p = 0.005] but did not significantly affect IL-6 or adiponectin. Among the IF modes, time-restricted feeding (TRF) showed the largest reduction in TNF-α [−0.39, p = 0.001]. TRF had the highest probability ranking for changes in IL-6, TNF-α, leptin, and adiponectin; however, the effects on IL-6 and adiponectin were not statistically significant. The 5:2 diet ranked highest for CRP. Conclusions: IF may be an effective dietary therapy for improving some inflammatory markers, with effects potentially influenced by the mode of IF. TRF had the highest rankings across multiple markers, though the findings were not uniformly significant. Additional longer-term trials are needed to fully elucidate the anti-inflammatory potential of IF.

Caffeine (CAF) mouth rinsing has been considered a practical nutritional strategy among athletes. Recent studies indicate that this nutritional strategy’s efficacy may depend on the athlete’s prandial state. Therefore, the main aim of the current study is to determine the effect of CAF mouth rinsing on a battery of soccer-specific tests of soccer players in fasted (FST) or fed states (FED). Thirteen male soccer players (age: 18.1 ± 0.9 years, body mass: 60.1 ± 8.4 kg, height: 174.2 ± 7.3 cm, and body mass index: 20.14 ± 2.7 kg/m ² ) randomly participated in a randomized, double-blind, Latin square study design. Participants completed four experimental trials while performing eight serial mouth rinses of 750-mg CAF or a taste-matched placebo (PLA) for 15 s and then immediately expectorated. Two trials commenced 2 hr after a high-carbohydrate breakfast (FED), and two trials were performed after an overnight fast (FST). Following the final mouth rinse, sprint test, countermovement jump, Yo-Yo Intermittent Recovery Test Level 1, and rating of perceived exertion were measured, respectively. There was a main effect of condition for Yo-Yo Intermittent Recovery Test Level 1 performance ( p = .021), while interaction between Condition × Prandial ( p = .671) and the main effect of prandial state ( p = .437) was not significant for Yo-Yo Intermittent Recovery Test Level 1 (CAF-FST = 2,155 ± 484 m, PLA-FST = 1,933 ± 549 m, CAF-FED = 2,098 ± 679 m, and PLA-FED = 1,864 ± 535 m). In addition, there was no significant main effect of condition, prandial, and interaction between Condition × Prandial for the sprint test and countermovement jump and the rating of perceived exertion (all p > .5). These data suggest that CAF mouth rinsing increases intermittent running performance in soccer players. This improvement is likely to be similar in the FST and FED states.