Abstract
Background Ergogenic nutritional supplementation is sought by professional athletes for improving physical performance; nevertheless, scientific evidence to support the chronic use of L-Arginine among water polo players is missing. Methods Seventeen male professional water polo players were randomly assigned to assume 5 grams per day of L-Arginine (n = 9) or placebo (n = 8) for 4 weeks. The players' fitness level was assessed in the maximal speed swimming test. Ear lobe blood samples taken before and after the effort for serum lactate content were analyzed. A speed-to-lactate ratio was generated at the baseline and after 4 weeks of treatment. We also tested the effects of L-Arginine in vitro, measuring NO production, mitochondrial respiration, and gene expression in human fibroblasts. Results L-Arginine did not modify BMI, muscle strength, and maximal speed at 200 meters after 4 weeks. However, L-Arginine ameliorated oxidative metabolism to exercise as suggested by the statistically significant lower lactate-to-speed ratio, which was not observed in placebo-treated controls. In vitro, L-Arginine induced the expression of a key regulator of mitochondrial biogenesis (PGC1α) and genes encoding for complex I and increased the production of nitric oxide and the maximal oxygen consumption rate. Conclusions Chronic L-Arginine is safe and effective in ameliorating the oxidative metabolism of professional water polo players, through a mechanism of enhanced mitochondrial function.
Highlights
The amino acid L-Arginine contributes to the regulation of energetic metabolism in cells, by participating in the Krebs cycle after conversion in citrulline [1]
In an in vitro model, we evaluated the effects of chronic exposure to increased L-Arginine concentration on parameters of mitochondrial biogenesis and function
Baseline performance measured as the maximal speed at the 200 meters was not different between the control and the L-Arginine groups
Summary
The amino acid L-Arginine contributes to the regulation of energetic metabolism in cells, by participating in the Krebs cycle after conversion in citrulline [1]. NO availability improves muscle mitochondrial respiration and biogenesis [3, 4] Some studies associate these biological features of NO with the amelioration of muscle force production and endurance performance and recovery [5, 6]. L-Arginine ameliorated oxidative metabolism to exercise as suggested by the statistically significant lower lactate-to-speed ratio, which was not observed in placebo-treated controls. L-Arginine induced the expression of a key regulator of mitochondrial biogenesis (PGC1α) and genes encoding for complex I and increased the production of nitric oxide and the maximal oxygen consumption rate. Chronic L-Arginine is safe and effective in ameliorating the oxidative metabolism of professional water polo players, through a mechanism of enhanced mitochondrial function
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