Caffeine And Sports Performance: Just A Matter Of Timing? A Pilot Study

Caffeine (CAF) is a performance-enhancing supplement for exercise and cognitive tasks through its effects on the central nervous system. Several factors may moderate these effects, including supplement timing, though little evidence exists to support this affirmation. PURPOSE: To determine the influence of timing of CAF supplementation on its exercise- and cognitive-performance enhancing capacity. METHODS: Eight recreationally trained participants (age: 25±5 y, body mass: 70.6 ± 7.6 kg) performed a familiarization to all experimental procedures followed by two main experimental visits in which participants received either CAF (4 mg/kg, CAF) or placebo (4 mg/kg flour, PLA). A computer-based Flanker test and three 20-m sprints were performed at four time points: baseline (0M), 30 (30M), 60 (60M) and 90 (90M) min following capsule ingestion. Data were analysed with liner mixed models nested by participant ID and corrected by baseline (0M) values. RESULTS: 20-m sprints: No interaction was significant (all p≥0.33). Moderate to large effect sizes were found for mean sprint time at 30M (d=0.9), 60M (d=0.7), and 90 m (d=0.5), and for best sprint time at 30M (d=0.8), 60M (d=0.7), and 90M (d=0.6), all favouring CAF. Flanker test: Except for accuracy after incongruent stimuli at 90M (p-value for interaction=0.02, post-hoc p-value =0.009, d=1.2), no other interactions were significant (all p≥0.30). Small effects were seen for overall reaction time at 30M (d=0.3), 60M (d=0.2), and 90M (d=0.4), and small to large effects for mean response time for congruent stimuli at 30M (d=0.9), 60M (d=0.5) and 90M (d=0.4), all benefitting CAF. CONCLUSION: Caffeine did not significantly influence 20-m sprint performance, although effect sizes were moderate to large in favour of CAF at all timepoints. Similarly, some cognitive performance differences were evident with CAF based on effect sizes. A lack of statistical significance is likely due to the small sample size. Since sprint performance was not significantly different between timepoints with placebo, these pilot data suggest that these exercise and cognitive tests may be suitable to determine the influence of timing on CAF’s performance-enhancing effect. São Paulo Research Foundation: 2021/06836-0; 2020/12036-3; 2021/12116-0