Can I Have My Coffee and Drink It? A Systematic Review and Meta-analysis to Determine Whether Habitual Caffeine Consumption Affects the Ergogenic Effect of Caffeine.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized/controlled caffeine supplementation trials
PubMed 35536449 · doi:10.1007/s40279-022-01685-0
What was done
Authors conducted a systematic review and three-level meta-analysis of 60 studies to evaluate whether habitual caffeine intake modifies the acute ergogenic effect of caffeine supplementation. Analyses assessed overall performance outcomes and sub-analyses based on exercise modality (endurance, power, strength), sex, training status, acute relative dose (<3, 3–6, >6 mg/kg body mass), dose relative to habitual intake (higher vs. lower), and withdrawal periods (<24, 24–48, >48 h).
What was found
Caffeine significantly improved exercise performance compared to placebo overall (standardized mean difference [SMD] = 0.25, 95% CI 0.20–0.30; p < 0.001), with no modifying effect of relative habitual caffeine consumption (p = 0.59). Ergogenic effects remained significant for acute doses <3 mg/kg (SMD = 0.26, 95% CI 0.12–0.40; p = 0.003) and 3–6 mg/kg (SMD = 0.26, 95% CI 0.21–0.32; p < 0.0001), but not >6 mg/kg (SMD = 0.11, 95% CI -0.07 to 0.30; p = 0.23). Performance improved whether the acute dose was higher (SMD = 0.26, 95% CI 0.20–0.31; p < 0.001) or lower (SMD = 0.21, 95% CI 0.06–0.36; p = 0.006) than habitual daily intake, and across all withdrawal windows. Habitual intake did not influence results across exercise types (all p ≥ 0.23), sex, or training level.
Why it matters
Habitual caffeine consumers maintain acute performance enhancements from caffeine supplementation, suggesting that pre-competition caffeine withdrawal or washouts are unnecessary to derive ergogenic benefits.
Limits
The abstract does not state the total number of individual participants across the 60 studies. Sub-analysis of doses >6 mg/kg was non-significant, potentially due to fewer studies at high doses. The findings are bounded by the reporting quality and methods of habitual caffeine intake estimation used in the underlying trials.
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- supports Recent research indicates that desensitizing yourself to caffeine by abstaining from it does not significantly alter its performance benefits.