Does citrulline make you cycle longer?
Ergogenic effects of a 10-day L-citrulline supplementation on time to exhaustion and cardiorespiratory and metabolic responses in healthy individuals: a double-blind, randomised, placebo-controlled crossover trial
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
L-citrulline raised arginine levels as expected—but none of the downstream physiological markers (heart output, oxygen use, lactate) improved.
The entire theory behind citrulline is that more arginine = more nitric oxide = better blood flow = better performance. This study proves that chain can break between biochemistry and real results.
Practical Takeaways
If you’re a cyclist or endurance athlete, skip citrulline for now—this study says it won’t help you last longer on the bike.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
L-citrulline raised arginine levels as expected—but none of the downstream physiological markers (heart output, oxygen use, lactate) improved.
The entire theory behind citrulline is that more arginine = more nitric oxide = better blood flow = better performance. This study proves that chain can break between biochemistry and real results.
Practical Takeaways
If you’re a cyclist or endurance athlete, skip citrulline for now—this study says it won’t help you last longer on the bike.
Publication
Journal
Frontiers in Sports and Active Living
Year
2025
Authors
M. Willems, Noah D ’ Unienville, O. Moser, Ergogenic, J. Schierbauer, L. Francis, F. Greco, P. Zimmermann
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Claims (6)
Taking L-citrulline by mouth raises your blood levels of L-arginine better than taking L-arginine directly, because your body processes L-citrulline more efficiently and doesn’t break it down too early in the liver.
Taking L-citrulline might only help with short, intense workouts like sprinting or weightlifting, but it doesn’t seem to make a difference in long, hard cycling rides—even if you take enough of it for long enough.
Taking L-citrulline pills for 10 days at a specific dose doesn’t seem to make healthy young adults feel sick—only a few people might get a little stomach upset.
Taking a specific amino acid supplement called L-citrulline for 10 days might help young women bike harder for a little longer, but the results weren’t strong enough to be sure — so scientists think it might work differently for women than for men, and more research is needed.
Taking a specific dose of L-citrulline for 10 days doesn’t make you bike harder, faster, or feel less tired—even though some people think it might help. Your heart, lungs, and muscles act the same as if you didn’t take it.