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Cited by 30Thermoregulation and physiological responsesMuscle metabolism and nutritionExercise and Physiological Responses

Failure of oral tyrosine supplementation to improve exercise performance in the heat

TUMILTY, LES, DAVISON, GLEN, BECKMANN, MANFRED, THATCHER, RHYS·2014·Medicine & Science in Sports & Exercise
DOI 10.1249/mss.0000000000000243
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Abstract

PURPOSE: Acute oral tyrosine administration has been associated with increased constant-load, submaximal exercise capacity in the heat. This study sought to determine whether self-paced exercise performance in the heat is enhanced with the same tyrosine dosage. METHODS: After familiarization, seven male endurance-trained volunteers, unacclimated to exercise in the heat, performed two experimental trials in 30°C (60% relative humidity) in a crossover fashion separated by at least 7 d. Subjects ingested 150 mg·kg(-1) body mass tyrosine (TYR) or an isocaloric quantity of whey powder (PLA) in 500 mL of sugar-free flavored water in a randomized, double-blind fashion. Sixty minutes after drink ingestion, the subjects cycled for 60 min at 57% ± 4% peak oxygen uptake (VO2peak) and then performed a simulated cycling time trial requiring completion of an individualized target work quantity (393.1 ± 39.8 kJ). RESULTS: The ratio of plasma tyrosine plus phenylalanine (tyrosine precursor) to amino acids competing for brain uptake (free-tryptophan, leucine, isoleucine, valine, methionine, threonine, and lysine) increased 2.5-fold from rest in TYR and remained elevated throughout exercise (P < 0.001), whereas it declined in PLA from rest to preexercise (P = 0.004). Time-trial power output (P = 0.869) and performance (34.8 ± 6.5 and 35.2 ± 8.3 min in TYR and PLA, respectively; P = 0.4167) were similar between trials. Thermal sensation (P > 0.05), RPE (P > 0.05), core temperature (P = 0.860), skin temperature (P = 0.822), and heart rate (P = 0.314) did not differ between trials. CONCLUSIONS: These data indicate that acute tyrosine administration did not influence self-paced endurance exercise performance in the heat. Plasma tyrosine availability is apparently not a key determinant of fatigue processes under these conditions.

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  • One study used an isocaloric whey protein drink as placebo, which contained some tyrosine but less than the active condition.

    “In one study, the placebo was an isocaloric whey protein drink, which means it contained some tyrosine, though less than the amount of tyrosine in the active condition (Tumilty et al., 2014).”

    From Behavioral and cognitive effects of tyrosine intake in healthy human adults (2015) · cites this paper as Tumilty et al., 2014

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Authors
TUMILTY, L., DAVISON, G., BECKMANN, M., & THATCHER, R.
Affiliations
  • Aberystwyth University (GB)
  • Universities at Medway (GB)
ORCID
Venue
Medicine & Science in Sports & Exercise
Publisher
Ovid Technologies (Wolters Kluwer Health)
Published
2014-07
Volume
46
Issue
7
Pages
1417-1425
ISSN
0195-9131 (ISSN-L)
DOI
10.1249/mss.0000000000000243
OpenAlex
W1979562144
Cited by
30
References
39
Citations by year
2026: 1 · 2025: 4 · 2024: 2 · 2023: 1 · 2022: 2 · 2021: 2 · 2020: 2 · 2019: 1 · 2018: 4 · 2017: 3 · 2016: 1 · 2015: 6 · 2014: 1
FWCI
2.44
Type
journal article
Language
en
Open access
closed
Locations
  • Medicine & Science in Sports & Exercise (publishedVersion)
  • PubMed (publishedVersion)
  • Kent Academic Repository (University of Kent) (submittedVersion)
Funders
Medical Research Council (MR/J010308/1)
Topics
  • Health Sciences › Medicine › Physiology › Thermoregulation and physiological responses
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Muscle metabolism and nutrition
  • Health Sciences › Medicine › Rehabilitation › Exercise and Physiological Responses
Keywords
tyrosine supplementation, exercise in the heat, self-paced cycling, endurance exercise performance, plasma tyrosine, phenylalanine, thermal sensation, perceived exertion, core body temperature, fatigue
MeSH terms
Administration, Oral, Adult, Amino Acids, Beverages, Bicycling, Body Temperature, Double-Blind Method, Heart Rate, Hot Temperature, Humans, Male, Phenylalanine, Skin Temperature, Thermosensing, Tyrosine, Exercise Tolerance, Cross-Over Studies, Dietary Supplements, Young Adult

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