Background
L-citrulline is an amino acid that is an endogenous precursor of L-arginine and contributes to generating nitric oxide (NO). L-citrulline is known for increasing plasma L-arginine and NO more effectively than equivalent doses of L-arginine. NO plays an important role in sport performance but it is presently unknown whether L-citrulline enhances sport performance during rowing ergometer competition in humans. The aim of this study is to investigate the effect of oral supplementation of L-citrulline on cycling time trial performance.