What the study found
Caffeine, glucose and their combination extended the final time-to-exhaustion test compared with placebo in simulated altitude conditions.
Participants and protocol
Eight active young men completed four double-blind crossover cycling trials, including ninety minutes of moderate work followed by a harder exhaustion test in a hypoxic chamber.
What this cannot establish
A percentage gain in time to exhaustion is not the same as that percentage improvement in race time. The small acute study does not establish a personal caffeine dose or a benefit at normal altitude.
Publication details
- Record
- PubMed 39519456
- Publication types
- research-article · Randomized Controlled Trial
- Indexed subjects
- Caffeine · Glucose · Blood Glucose · Exercise · Cross-Over Studies
- Source record checked
- 2026-10-18
Publication type and subject indexing describe the record; they are not a quality grade or proof of a benefit. An abstract does not replace a review of the full methods and results.
Adaptive AI coach for iPhone
Meet your adaptive AI coach.
Tell your coach what you are training for. It builds the plan, follows the work you complete, and adapts upcoming training when recovery, your schedule, or real life changes.
Keep going
Performance Science Lab
Research summaries for endurance athletes, with study context, practical protocols, and clear limitations.
Open guideSupplements performance research
Supplements are optional. Only a few reliably move the needle, and context matters.
Open guideTime-trial performance research for endurance athletes
Practical performance outcome used in many studies: closer to racing than lab-only metrics.
Open guide