l-Citrulline-malate influence over branched chain amino acid utilization during exercise
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Exhaustive exercise induces disturbances in metabolic homeostasis which can result in amino acid catabolism and limited l-arginine availability. Oral l-citrulline supplementation raises plasma l-arginine concentration and augments NO-dependent signalling. Our aim was to evaluate the effects of diet supplementation with l-citrulline-malate prior to intense exercise on the metabolic handle of plasma amino acids and on the products of metabolism of arginine as creatinine, urea and nitrite and the possible effects on the hormonal levels. Seventeen voluntary male pre-professional cyclists were randomly assigned to one of two groups: control or supplemented (6 g l-citrulline-malate 2 h prior exercise) and participated in a 137-km cycling stage. Blood samples were taken in basal conditions, 15 min after the race and 3 h post race (recovery). Most essential amino acids significantly decreased their plasma concentration as a result of exercise; however, most non-essential amino acids tended to significantly increase their concentration. Citrulline-malate ingestion significantly increased the plasma concentration of citrulline, arginine, ornithine, urea, creatinine and nitrite (p < 0.05) and significantly decreased the isoleucine concentration from basal measures to after exercise (p < 0.05). Insulin levels significantly increased after exercise in both groups (p < 0.05) returning to basal values at recovery. Growth hormone increased after exercise in both groups, although the increase was higher in the citrulline-malate supplemented group (p < 0.05). l-citrulline-malate supplementation can enhance the use of amino acids, especially the branched chain amino acids during exercise and also enhance the production of arginine-derived metabolites such as nitrite, creatinine, ornithine and urea.
KeywordsOxidative stress Insulin Growth hormone Nitric oxide Arginine
This work has been granted the Spanish Ministry of Science and Education [Projects DEP2005-00238-CO4-01/EQUI and DEP2005-00238-CO4-02/EQUI], the Spanish Ministry of Health [DPS2008-07033-C03-03] and the FEDER funding. The authors are grateful to Laboratorio Pérez Giménez, Córdoba, Spain. All the authors state that the results of the present study do not constitute endorsement by ACSM.
Conflicts of interest statement
Authors do not have conflict of interest with any organisation with a financial interest, direct or indirect, in the subject matter or materials discussed in the manuscript that may affect the conduct or reporting of the work submitted.
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