November 6, 2002 (Cox News Service) -- An amino acid supplement called L-tyrosine, recommended by fitness trainers and sold by supplement outlets as an endurance booster, has no effect on endurance, according to a new Brigham Young University study.
"There wasn't any indication from our tests that tyrosine had an effect in the blood or in the brain," said Allen Parcell, assistant professor in the Human Performance Research Center at BYU. "Tyrosine didn't improve endurance performance in our subjects."
The results of the study, financed in part by the Gatorade Sports Science Institute, are reported in the November issue of the Journal of Applied Physiology .
The BYU team followed up on previous studies in animals that suggested the possibility of "fooling" the brain to prevent fatigue.
Parcell and his colleagues tested the supplement with sports cyclists, giving each a sports drink. Some of the drinks contained tyrosine, others a basic carbohydrate like glucose, and others a combination of both.
In the end, the cyclists taking tyrosine saw no change in their endurance.
Copyright 2002 Cox News Service. All rights reserved.
