l-Citrulline supplementation improves O2 uptake kinetics and high-intensity exercise performance in humans

May 30, 2015Journal of applied physiology (Bethesda, Md. : 1985)

l-Citrulline supplements improve oxygen use and high-intensity exercise performance in people

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Abstract

Plasma nitrite concentration increased with l-arginine supplementation and may increase with l-citrulline supplementation.

L-citrulline supplementation significantly increased plasma citrulline concentration, while l-arginine did not.
Nitric oxide biomarkers showed an increase in plasma nitrite with l-arginine, and a tendency to increase with l-citrulline compared to placebo.
Mean arterial blood pressure was lower after l-citrulline supplementation.
L-citrulline reduced the mean response time for oxygen uptake during severe-intensity cycling.
Exercise tolerance and total work completed improved with l-citrulline but were unaffected by l-arginine supplementation.

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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 (V̇o2) kinetics, and exercise performance. In a randomized, placebo (Pla)-controlled, crossover study, 10 healthy adult men completed moderate- and severe-intensity cycling exercise on days 6 and 7 of a 7-day supplementation period with Pla, Arg (6 g/day), and Cit (6 g/day). Compared with Pla, plasma Arg concentration was increased by a similar magnitude with Arg and Cit supplementation, but plasma Cit concentration was only increased (P < 0.001) with Cit supplementation. Plasma nitrite (NO2 (-)) concentration was increased with Arg supplementation (P < 0.05) and tended to increase with Cit supplementation (P = 0.08) compared with Pla (83 ± 25, 106 ± 41, and 100 ± 38 nM with Pla, Arg, and Cit, respectively); however, mean arterial blood pressure was only lower (P < 0.05) after Cit supplementation. The steady-state V̇o2 amplitude during moderate-intensity cycle exercise was not significantly different between supplements, but Cit lowered the V̇o2 mean response time (59 ± 8 and 53 ± 5 s with Pla and Cit, respectively, P < 0.05) during severe-intensity exercise, improved tolerance to severe-intensity exercise (589 ± 101 and 661 ± 107 s with Pla and Cit, respectively), and increased the total amount of work completed in the exercise performance test (123 ± 18 and 125 ± 19 kJ with Pla and Cit, respectively, 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, V̇o2 kinetics, and exercise performance in healthy adults.

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l-Citrulline supplementation improves O2 uptake kinetics and high-intensity exercise performance in humans

Abstract

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