31-P MRS analysis of muscle energetics changes associated to citrulline-malate in humans

Aim - The purpose of this study was to determine the effects of citrulline malate (CM) supplementation on high-energy phosphate metabolism. Materials and methods - Eighteen male subjects were included in the study A rest-exercise (fingers flexions)recovery protocol was performed twice before (D-7 and D0), three times during and once after (D22) a 15-day supplementation protocol in which 6 g/day of CIM were ingested by the subjects. High energy phosphate metabolism was analysed by 31-P magnetic resonance spectroscopy at 4. 7 T: Results - Results obtained twice before the CM ingestion did not show any difference thereby demonstrating the high reproducibility of the measurements and showing no learning effect due to the repetition of the protocol. The statistical analysis of the metabolic changes associated to CM ingestion in the whole group tended to demonstrate an improvement of the mechanical performance whereas PCr consumption and acidosis were similar (R2 = 0.29 +/- 0.03 pH unit/W before treatment vs 0.23 +/- 0.02 pH unit/W during treatment, p = 0.02). Also, the recovery kinetics of PCr improved after treatment as a sign of a faster oxidative ATP production (Virec = 16.8 +/- 2.8 mM PCr/min before treatment vs 24.1 +/- 3.1 mM PCr/min during treatment, p = 0.01). Metabolic parameters measured after treatment were not significantly different from those measured before. Conclusion - These results are in favour of a transient activation of mitochondrial metabolism induced by CM treatment likely as a result of an enhanced malate supply. (C) 2001 Editions scientifiques et medicales Elsevier SAS.