Study note • PMID 10694138
The effect of caffeine on endurance performance after nonselective beta-adrenergic blockade.
Worth trying if it fits your goal and context.
ELI5
In plain language
This study was designed to test the hypothesis that combined administration of propranolol and caffeine (Pr+C) would increase endurance performance compared with the administration of propranolol alone (Pr) if… (randomized trial; participants).
The abstract doesn’t indicate a clear change in Time-trial performance, Time to exhaustion under the tested conditions. Treat this as a signal, not a guarantee; confirm methods and context in the full paper.
Takeaways
What the abstract suggests
- • Study question: This study was designed to test the hypothesis that combined administration of propranolol and caffeine (Pr+C) would increase endurance performance compared with the administration of propranolol alone (Pr) if…
- • The abstract doesn’t indicate a clear change in Time-trial performance, Time to exhaustion under the tested conditions.
- • Population: participants.
- • Protocol cues (title/abstract): 5 mg • 20.4 min • 10.8 min • 17.2 min.
Protocol
Protocol (as reported)
- • Intervention/exposure: caffeine (vs placebo).
- • Dose/time/duration cues in abstract/title: 5 mg • 20.4 min • 10.8 min • 17.2 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 (participants) 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: participants.
- • Comparator: placebo.
- • Outcomes measured: Time-trial performance, Time to exhaustion.
- • Protocol cues mentioned: 5 mg • 20.4 min • 10.8 min • 17.2 min.
- • Source: PubMed PMID 10694138 (2000) — Medicine and science in sports and exercise.
Results excerpt
What the abstract reports
“Although there was a clear tendency for an improved performance in the Pr+C trial compared to the Pr trial, this improvement was not associated with increased plasma FFA concentration and/or reduced plasma potassium concentration in the Pr+C compared to the Pr trial.”
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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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.