Study note • PMID 29509641
Caffeine, CYP1A2 Genotype, and Endurance Performance in Athletes.
Worth trying if it fits your goal and context.
ELI5
In plain language
Many studies have examined the effect of caffeine on exercise performance, but findings have not always been consistent. (randomized trial; n=101 athletes).
Effects on Time-trial performance are mixed or unclear from the abstract alone. Treat this as a signal, not a guarantee; confirm methods and context in the full paper.
Takeaways
What the abstract suggests
- • Study question: Many studies have examined the effect of caffeine on exercise performance, but findings have not always been consistent.
- • Effects on Time-trial performance are mixed or unclear from the abstract alone.
- • Population: n=101 athletes.
- • Protocol cues (title/abstract): 4 mg • 2 mg • 0.1 min • 0.4 min • 0.5 min.
Protocol
Protocol (as reported)
- • Intervention/exposure: caffeine (vs placebo).
- • Dose/time/duration cues in abstract/title: 4 mg • 2 mg • 0.1 min • 0.4 min • 0.5 min.
- • Outcomes: Time-trial performance, Time to exhaustion.
- • Replication note: abstracts often omit adherence and timing; confirm details before changing training or supplementation.
Fit
Who it helps, and who should skip it
Who it helps
- • Athletes similar to the study population (n=101 athletes) working on supplements.
- • Athletes who can measure Time-trial performance, Time to exhaustion with a repeatable workout or time-trial effort.
Who should skip
- • If you have symptoms or conditions that make the intervention risky, get professional guidance.
- • If you’re near race day and can’t safely test, defer the experiment.
Methods
What the study actually did
- • Design: randomized trial (double-blind, placebo-controlled).
- • Population: n=101 athletes.
- • Comparator: placebo.
- • Outcomes measured: Time-trial performance, Time to exhaustion.
- • Protocol cues mentioned: 4 mg • 2 mg • 0.1 min • 0.4 min • 0.5 min.
- • Source: PubMed PMID 29509641 (2018) — Medicine and science in sports and exercise.
Results excerpt
What the abstract reports
“Overall, 4 mg.kg caffeine decreased cycling time by 3% (mean +/- SEM) versus placebo (17.6 +/- 0.1 vs 18.1 +/- 0.1 min, P = 0.01).”
Note: excerpts are short; for full context, read the paper.
Limits
Limitations & bias
- • Abstract-only summaries can miss critical details (population, protocol, adherence, and context).
- • Single studies often don’t generalize to your event, history, and training load; treat results as a starting point.
- • If your context differs (elite vs recreational; cycling vs running), adjust expectations and be conservative.
- • This is performance information, not medical advice.
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Performance Science Lab
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Caffeine for endurance performance: a practical protocol
Evidence-informed protocol: Caffeine for endurance performance: a practical protocol. Practical steps, who it helps, and what to watch out for.
Time-trial performance research for endurance athletes
Practical performance outcome used in many studies: closer to racing than lab-only metrics.
Time to exhaustion research for endurance athletes
A lab outcome that can still guide training: it often tracks fatigue resistance.