The Study
Comparative effects of caffeine and paraxanthine on rowing performance and sleep quality: a randomized crossover study
This study tested what happens when rowers take different pills before racing. It found that taking both caffeine and paraxanthine together might help them row a little faster, but taking either one alone didn't clearly help. It also found that caffeine made people feel like they slept worse. But because only 14 people were tested, we can't be super sure these results are true for everyone.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Scientists tested if caffeine, its natural byproduct (paraxanthine), or both help rowers go faster and sleep better after evening workouts.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 562 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1A 3.3-second improvement in a 2000m row is small but could matter in close races; better sleep from paraxanthine could help recovery for athletes training late.
- 2When rowers took both caffeine and paraxanthine together, they rowed 3.3 seconds faster and produced 8 more watts of power.
- 3Paraxanthine alone didn’t help speed or power.
- 4But when rowers took caffeine (alone or with paraxanthine), they reported worse sleep and more daytime tiredness than when they took paraxanthine alone.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of the International Society of Sports Nutrition
Year
2026
Authors
Azize Bingol Diedhiou, Ulas Can Yildirim, Serhat Ozdenk, Dilara Erkan, Izzet Karakulak, Selin Yıldırım Tuncer, Murat Turğut, Mehmet Can Gundem, Mehmet Veysi Bora, Fırat Akça
Related Content
Claims (6)
A 200 mg dose of paraxanthine does not improve rowing performance time or power output in male university rowers compared to a placebo.
Male university rowers who consume caffeine report worse sleep quality and more daytime sleepiness the next day than when they consume paraxanthine alone.
In athletes training in the evening, 200 mg of paraxanthine is linked to improved sleep quality compared to caffeine, with no measurable difference in athletic performance.
When caffeine and paraxanthine are taken together, the performance improvement is caused by the body converting caffeine into paraxanthine, not by the two substances working together directly.
Male university rowers who consumed 200 mg caffeine and 200 mg paraxanthine together rowed 2000 meters 3.3 seconds faster and produced 8 watts more average power than when they took a placebo during evening training.
Consuming caffeine in the afternoon or evening reduces sleep quality.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.