Caffeine expectancy does not improve interval running performance in trained runners
In a randomized controlled crossover trial, trained runners who believed they had consumed caffeine (placebo) showed no significant improvement in total session time for 5 x 1000-m interval running compared to a control condition (1021.50 ± 114.01 vs. 1017.23 ± 109.08 s, p = 0.270, ES = 0.31). No differences were found in pacing, heart rate, perceived exertion, or running kinematics, but participants reported increased feelings of activeness and some caffeine-related side effects (e.g., increased urine production, sleep disturbances) under the placebo condition.
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Caffeine expectancy does not improve interval running performance in trained runners The current body of evidence comprises 1 study, including 1 randomized controlled trial. EvidenceHub rates the overall confidence at 44/100 (low).
The Claim
Caffeine expectancy does not improve interval running performance in trained runners
This conclusion is most relevant to: Moderately trained runners (14 participants).
What the Research Shows
The conclusion draws on 1 linked study. Highlights from the cited literature:
- ▸Caffeine Expectancy Does Not Affect Interval Running Performance, Physiological Responses, or Running Kinematics in Trained Runners: A Randomized Controlled Crossover Trial. (Nutrients, 2026) —
How It Works
The proposed biological pathway:
- ▸Participants ingested a placebo capsule believed to contain caffeine
- ▸Expectancy of caffeine intake was created
- ▸Physiological and performance measures were recorded during interval running
- ▸No significant ergogenic effect was observed, but subjective side effects were reported
Who Might Benefit
Evidence fit by population:
- ▸Moderately trained runners (14 participants)
Recommended Dose
N/A
Limitations & Caveats
Important context when interpreting this evidence:
- ▸Small sample size (n=14) may limit statistical power
- ▸Only moderately trained runners, not elite athletes
- ▸Single dose of placebo (3 mg·kg-1) may not reflect typical caffeine doses
- ▸Outdoor track conditions may introduce variability
Frequently Asked Questions
Does caffeine expectancy improve running performance?▼
No, this study found no significant improvement in interval running performance when runners believed they had consumed caffeine.
What was the effect size for the difference in performance?▼
The effect size was 0.31, which is small, and the difference was not statistically significant (p = 0.270).
Did caffeine expectancy affect any outcomes?▼
Yes, participants reported greater feelings of activeness and higher ratings of some caffeine-related side effects, such as increased urine production and sleep disturbances.
Who were the participants in this study?▼
The study included 14 moderately trained runners who completed two 5 x 1000-m interval training sessions.
References
- 1.Valero F, González-Mohíno F, Alda-Blanco A, Rodríguez-Barbero S, Muñoz de la Cruz V, Juárez Santos-García D, Salinero JJ. “Caffeine Expectancy Does Not Affect Interval Running Performance, Physiological Responses, or Running Kinematics in Trained Runners: A Randomized Controlled Crossover Trial..” Nutrients, 2026. PMID: 42588115 DOI: 10.3390/nu18152492