Carnitine in muscle, serum, and urine of nonprofessional athletes: effects of physical exercise, training, and L-carnitine administration.

TitleCarnitine in muscle, serum, and urine of nonprofessional athletes: effects of physical exercise, training, and L-carnitine administration.
Publication TypeJournal Article
Year of Publication1991
AuthorsArenas, J, Ricoy, JR, Encinas, AR, Pola, P, D'Iddio, S, Zeviani, M, DiDonato, S, Corsi, M
JournalMuscle Nerve
Volume14
Issue7
Pagination598-604
Date Published1991 Jul
ISSN0148-639X
KeywordsAdult, Carnitine, Exercise, Female, Humans, Male, Muscles, Physical Education and Training, Physical Endurance, Running
Abstract

Efficient utilization of fatty acids to sustain prolonged physical efforts is thought to be dependent on the carnitine shuttle of muscle. A study has been carried out in 24 athletes (13 long-distance runners and 11 sprinters). These subjects received placebo or L-carnitine (1 g/orally b.i.d.) during a 6-month period of training. In endurance athletes, training induced lowering of total and free muscle carnitine. Increase of esterified muscle carnitine was also observed. Post-exertional overflow of acetylcarnitine and long-chain acylcarnitine, as well as reduction of the free fraction was also noticed in the blood. Fasting plasma carnitine levels, however, were not affected in carnitine-treated athletes at rest. These changes were likely related with the significantly increased urinary excretion of esterified and total carnitine which occurred after physical exercise. In the sprinters only, a decrease in free and total carnitine of muscle was detected after training. Both these potentially unfavorable effects were prevented by oral administration of L-carnitine. Our data suggest that training in endurance athletes, and to a lesser extent, in sprinters, is associated with a decrease in free and total carnitine of muscle, due to an increased overflow of short-chain carnitine esters in urine.

DOI10.1002/mus.880140703
Alternate JournalMuscle Nerve
Citation Key10.1002/mus.880140703
PubMed ID1922166