Popular sports supplement has no effect on endurance

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.”