Effects of acute versus chronic L-carnitine L-tartrate supplementation on metabolic responses to steady state exercise in males and females

Twelve healthy active subjects (6 male, 6 female) performed 60 min of exercise (60% VO2max) on 3 occasions after supplementing with L-Carnitine L-tartrate (LCLT) or placebo. Each Subject received a chronic dose, an acute dose, and placebo in a randomized, double-blind crossover design. Dietary intake and exercise were replicated for 2 d prior to each trial. In males there was a significant difference in rate of carbohydrate (CHO) oxidation between placebo and chronic trials (P = 0.02) but not placebo and acute trials (P = 0.70), and total CHO oxidation was greater following chronic supplementation vs. placebo (mean +/- standard deviation) of 93.8 (17.3) g/hr and 78.2 (23.3) g/h, respectively). In females, no difference in rate of, or total, CHO oxidation was observed between trials. No effects on fat oxidation or hematological responses were noted in either gender group. Under these experimental conditions, chronic LCLT supplementation increased CHO oxidation in males during exercise but this was not observed in females.