title: Ingestion of tyrosine: effects on endurance, muscle strength, and anaerobic performance.
abstract: Acute tyrosine ingestion is thought to improve aerobic endurance, muscle strength and endurance, and anaerobic power of men undergoing severe physiologic stress. In a double-blind, crossover study, 20 men (32 +/- 1 y old) underwent 2 loadcarriage treadmill sessions, 1 after taking tyrosine (150 mg/ kg L-crystalline tyrosine) and 1 after taking placebo. Tyrosine dosage was based on subject weight and ingested 30 min before load carriage. A physical performance battery was administered after the load carriage: maximal and submaximal handgrip, pull-ups, and stair stepping with weight. Total time on treadmill was not significantly lengthened with ingestion of tyrosine (118.9 +/- 1.4 min) as compared with placebo (119.2 +/- 1.2 min). Total power for stair stepping (tyrosine 223 +/- 8 watts, placebo 216 +/- 9 watts) and muscle strength and endurance (handgrip) was not significantly improved by tyrosine ingestion. The results indicate that acute ingestion of tyrosine by healthy men has no measurable effect on endurance, muscle strength, or anaerobic power.
authors.affiliation: Dept of Military and Emergency Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA.
authors.forename: Erin E
authors.initials: EE
authors.lastname: Sutton
authors.forename: M Regina
authors.initials: MR
authors.lastname: Coill
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Deuster
mesh_terms: D000328:Adult; D015308:Anaerobic Threshold; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005080:Exercise Test; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D010807:Physical Endurance / Q000187:drug effects* / Q000502:physiology; D014443:Tyrosine / Q000008:administration & dosage / Q000494:pharmacology*; D014891:Weight Lifting / Q000502:physiology*
chemical_list: D014443:Tyrosine