Abstract
This study aimed to examine the effect of L-ornithine hydrochloride ingestion on lipid oxidation during submaximal endurance exercise following resistance exercise. Ten healthy young male adults with no history of regular resistance exercise (age: 26.0 +/- 4.4) conducted resistance exercise after L-ornithine hydrochloride or placebo ingestion (0.1 g/kg). Subjects exercised for 60 min on an ergometer at 50% VO2peak 120 min after resistance exercise. Plasma ornithine concentrations measured immediately, 120min and 180min after resistance exercise in the L-ornithine hydrochloride ingestion condition were significantly greater than those in the placebo condition. No significant difference was found in serum growth hor mone concentrations between both conditions (F = 4.4, p = 0.065). Serum free fatty acid concentrations were significantly greater immediately after submaximal ergometer bicycle exercise in both conditions than those before ingestion, immediately after resistance exercise and 120min after resistance exercise (F = 43.4, p .001, 300% - 508%), but no significant difference was found between both conditions (F = 3.6, p = 0.090). A similar trend was observed in serum ketone bodies as well. Although total energy production during submaximal ergometer exercise did not significantly differ (t = 0.74, p = 0.238), a significant difference was found in energy production via carbohydrate and lipid oxidation; the former was greater in the Lornithine hydrochloride ingestion condition (t = 1.89, p = 0.046, d = 0.44, 106%), and the latter was greater in the placebo condition (t = 1.89, p = 0.046, d = 0.78%, 145%). From the above, L-ornithine hydrochloride ingestion may not affect lipid metabolism during submaximal endurance exercise following resistance exercise. It may be involved in energy production via carbohydrate oxidation with glucogenic amino acid.
Highlights
A training program composed of resistance and endurance exercises has been widely recommended to control body mass and to maintain health [1,2,3,4]
This study aimed to examine the effect of L-ornithine hydrochloride ingestion on lipid oxidation during submaximal endurance exercise following resistance exercise
Total energy production during submaximal ergometer exercise did not significantly differ (t = 0.74, p = 0.238), a significant difference was found in energy production via carbohydrate and lipid oxidation; the former was greater in the L-ornithine hydrochloride ingestion condition (t = 1.89, p = 0.046, d = 0.44, 106%), and the latter was greater in the placebo condition
Summary
A training program composed of resistance and endurance exercises has been widely recommended to control body mass and to maintain health [1,2,3,4]. Various combinations of these two exercise modes are generally conducted on the same day. Resistance exercise, which preceded endurance exercise in this experiment, stimulates the endocrine response and markedly increases hormone secretion [6]. Growth hormone secretion is enhanced by resistance exercise and aerobic exercise, and oral ingestion of free amino acids such as ornithine and arginine [11,12,13,14]
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