Effect of L-carnitine on submaximal exercise metabolism after depletion of muscle glycogen

The effect of L-carnitine on energy metabolism at a high lipolytic flux was studied. Nine healthy male subjects received L-carnitine (CARN) (3 g.d-1) for 7 d, or a placebo (CONT), both with Ca pentothenate. The treatment increased resting nitrogen excretion slightly (+15%, P < 0.02). After an ove...

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Bibliographic Details
Published in:Medicine and science in sports and exercise 1993-06, Vol.25 (6), p.733-740
Main Authors: Decombaz, J, Deriaz, O, Acheson, K, Gmuender, B, Jequier, E
Format: Article
Language:English
Subjects:
Adult
Bicarbonates - metabolism
Calorimetry - methods
Carbohydrate Metabolism
Carbon Dioxide - metabolism
Carnitine - blood
Carnitine - pharmacology
Carnitine - urine
Cell Membrane Permeability - drug effects
Double-Blind Method
Energy Metabolism - drug effects
Exercise Test
Glycogen - metabolism
Humans
Lactates - blood
Lipid Metabolism
Male
Muscles - metabolism
Nitrogen - urine
Oxygen Consumption - drug effects
Physical Exertion - physiology
Placebos
Pulmonary Gas Exchange
Space life sciences
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Summary:The effect of L-carnitine on energy metabolism at a high lipolytic flux was studied. Nine healthy male subjects received L-carnitine (CARN) (3 g.d-1) for 7 d, or a placebo (CONT), both with Ca pentothenate. The treatment increased resting nitrogen excretion slightly (+15%, P < 0.02). After an overnight fast, the subjects were submitted successively to 20 min bicycle exercise at 43 +/- 2 (SEM) %VO2max, a glycogen depletion routine involving high intensity bouts to exhaustion, 1-2 h of rest, again 20 min at the initial load, and finally 20 min at 57 +/- 3 %VO2max. After glycogen depletion, blood short-chain acylcarnitine concentrations increased 5 times as much in CARN as in CONT (P < 0.02). Fat oxidation estimated from respiratory gas exchange doubled after glycogen depletion for the same exercise intensity. However, there were no treatment differences in nonprotein RQ, heart rate, perceived fatigue, and blood parameters. It is concluded that during submaximal exercise after glycogen depletion (i.e., at a high lipid flux) substrate metabolism is not influenced by L-carnitine supplementation.
ISSN:0195-9131
DOI:10.1249/00005768-199306000-00014