L-citrulline supplementation improves O2 uptake kinetics and high-intensity exercise performance in humans
Bailey, Stephen J.; Blackwell, James R.; Lord, T; et al.Vanhatalo, A; Winyard, Paul G.; Jones, Andrew M.
Date: 28 May 2015
Journal of Applied Physiology
American Physiological Society
The purpose of this study was to compare the effects of L-citrulline (CIT) and L-arginine (ARG) supplementation on nitric oxide (NO) biomarkers, pulmonary O2 uptake (VO2) kinetics and exercise performance. In a randomised, placebo-controlled, cross-over study, ten healthy adult males completed moderate- and severe-intensity cycling ...
The purpose of this study was to compare the effects of L-citrulline (CIT) and L-arginine (ARG) supplementation on nitric oxide (NO) biomarkers, pulmonary O2 uptake (VO2) kinetics and exercise performance. In a randomised, placebo-controlled, cross-over study, ten healthy adult males completed moderate- and severe-intensity cycling exercise on days 6 and 7 of a 7 day supplementation period with placebo (PLA), 6 g•day(-1) of ARG and 6 g•day(-1) of CIT. Compared to PLA, plasma [ARG] was increased by a similar magnitude with ARG and CIT supplementation, but plasma [CIT] was only increased (P<0.001) with CIT supplementation. Plasma nitrite concentration ([NO2 (-)]) was increased with ARG (P<0.05), and tended to increase with CIT (P=0.08), compared to PLA (PLA: 83 ± 25, ARG: 106 ± 41, CIT: 100 ± 38 nM); however, mean arterial blood pressure was only lower (P<0.05) after CIT supplementation. The steady state VO2 amplitude during moderate-intensity cycle exercise was not significantly different between supplements, but CIT speeded overall VO2 kinetics (PLA: 59 ± 8, CIT: 53 ± 5 s; P<0.05) during severe-intensity exercise, improved tolerance to severe-intensity exercise (PLA: 589 ± 101, CIT: 661 ± 107 s) and increased the total amount of work completed in the exercise performance test (PLA: 123 ± 18, CIT: 125 ± 19 kJ; P<0.05). These variables were not altered by ARG supplementation (P>0.05). In conclusion, these results suggest that short-term CIT, but not ARG, supplementation can improve blood pressure, VO2 kinetics and exercise performance in healthy adults.
Institute of Biomedical & Clinical Science
College of Medicine and Health
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