ORIGINAL RESEARCH article
Front. Sports Act. Living
Sec. Sport and Exercise Nutrition
Volume 7 - 2025 | doi: 10.3389/fspor.2025.1627743
Ergogenic Effects of a 10-Day L-Citrulline Supplementation on Time to Exhaustion and Cardiorespiratory and Metabolic Responses in Healthy Individuals. A Double-Blind, Randomized, Placebo-Controlled Crossover Trial
Provisionally accepted
- 1University of Bayreuth, Bayreuth, Germany
- 2University of Rome Foro Italico, Rome, Italy
- 3Medical University of Graz, Graz, Austria
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L-citrulline supplementation has been the topic of debate for its potential to augment L-arginine bioavailability, nitric oxide production, however, it remains uncertain whether it can truly serve as an ergogenic aid in endurance exercise performance. While it was previously recommended to include higher continuous doses of L-citrulline over ≥7 days, this study aimed to investigate whether relative dosing strategies using 100 mg•kg-1 per day over 10 days improve time to exhaustion (TTE) in young healthy adults.Twenty healthy, moderately active adult participants (9 females, age: 24.4±0.9 years, BMI: 24.0±2.5 kg•m-2 , VO2max: 43.5±6.3 mL•min-1•kg-1 ) received 100 mg•kg-1 per day for ten days of either L-citrulline (CIT) or a placebo (PLA) in a double-blind, randomized, placebocontrolled crossover trial before they performed two TTE tests at 5 % above the second lactate turnpoint (LTP2). Cardiac output (Q), oxygen uptake (VO2), glucose [Glu-] and lactate concentrations [La-] as well as rating of perceived exertion (RPE) were quantified during each test.There was no statistically significant difference in TTE between the trial arms (CIT: 20.5±7.3 vs. PLA: 19.8±5.7 minutes, p=0.43), however, a trend was observed for the female subgroup (24.4±6.2 vs. 21.9±4.8 minutes, p=0.06). Cardiac output (Q) also did not show significant differences between mean (CIT: 18.3±3.7 L•min-1 ; PLA: 19.0±4.5 L•min-1 , p=0.40) and maximum values (CIT: 28.7±5.7 L•min-1 ; PLA: 26.6±4.9 L•min-1 , p=0.22) in comparison of trial arms. Mean V ̇O2 was 1.77 ± 0.28 L•min -1 (CIT) and 1.84 ± 0.25 L•min -1 (PLA, p = 0.06), respectively. Mean maximum systolic (165 ± 17 vs. 171 ± 18 mm Hg, p = 0.23) and diastolic (81 ± 6 vs. 83 ± 6 mm Hg, p = 0.19) blood pressures were also not significantly different between CIT and PLA trial arms.Higher continuous doses of L-citrulline over 10 days do not increase TTE in healthy, moderately active individuals when compared to a placebo. Therefore, it is reasonable to assume that L-citrulline does not offer an ergogenic benefit for endurance performance.However, future research may focus on female populations or exercise protocols that involve longer distances to simulate competition.
Keywords: endurance performance, lactate turnpoint, Nitric Oxide, Cardiac Output, Cycling
Received: 13 May 2025; Accepted: 04 Aug 2025.
Copyright: © 2025 Schierbauer, Francis, Greco, Zimmermann and Moser. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Janis Schierbauer, University of Bayreuth, Bayreuth, Germany
Othmar Moser, University of Bayreuth, Bayreuth, Germany
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