title: Effect of tyrosine ingestion on cognitive and physical performance utilising an intermittent soccer performance test (iSPT) in a warm environment.
abstract: OBJECTIVE
  The aim of this study was to investigate the effect of tyrosine (TYR) ingestion on cognitive and physical performance during soccer-specific exercise in a warm environment.
  
  
  METHODS
  Eight male soccer players completed an individualised 90 min soccer-simulation intermittent soccer performance test (iSPT), on a non-motorised treadmill, on two occasions, within an environmental chamber (25 °C, 40 % RH). Participants ingested tyrosine (TYR; 250 mL sugar free drink plus 150 mg kg body mass(-1) TYR) at both 5 h and 1 h pre-exercise or a placebo control (PLA; 250 mL sugar free drink only) in a double-blind, randomised, crossover design. Cognitive performance (vigilance and dual-task) and perceived readiness to invest physical effort (RTIPE) and mental effort (RTIME) were assessed: pre-exercise, half-time, end of half-time and immediately post-exercise. Physical performance was assessed using the total distance covered in both halves of iSPT.
  
  
  RESULTS
  Positive vigilance responses (HIT) were significantly higher (12.6 ± 1.7 vs 11.5 ± 2.4, p = 0.015) with negative responses (MISS) significantly lower (2.4 ± 1.8 vs 3.5 ± 2.4, p = 0.013) in TYR compared to PLA. RTIME scores were significantly higher in the TYR trial when compared to PLA (6.7 ± 1.2 vs 5.9 ± 1.2, p = 0.039). TYR had no significant (p > 0.05) influence on any other cognitive or physical performance measure.
  
  
  CONCLUSIONS
  The results show that TYR ingestion is associated with improved vigilance and RTIME when exposed to individualised soccer-specific exercise (iSPT) in a warm environment. This suggests that increasing the availability of TYR may improve cognitive function during exposure to exercise-heat stress.
authors.affiliation: Department of Sport Science and Physical Activity, Institute for Sport and Physical Activity Research (ISPAR), University of Bedfordshire, Bedford, UK.
authors.forename: Nicole A
authors.initials: NA
authors.lastname: Coull
authors.forename: Samuel L
authors.initials: SL
authors.lastname: Watkins
authors.forename: Jeffrey W F
authors.initials: JW
authors.lastname: Aldous
authors.forename: Lee K
authors.initials: LK
authors.lastname: Warren
authors.forename: Bryna C R
authors.initials: BC
authors.lastname: Chrismas
authors.forename: Benjamin
authors.initials: B
authors.lastname: Dascombe
authors.forename: Alexis R
authors.initials: AR
authors.lastname: Mauger
authors.forename: Grant
authors.initials: G
authors.lastname: Abt
authors.forename: Lee
authors.initials: L
authors.lastname: Taylor
mesh_terms: D001143:Arousal / Q000187:drug effects; D054874:Athletic Performance; D003071:Cognition / Q000187:drug effects*; D019587:Dietary Supplements; D005080:Exercise Test; D006358:Hot Temperature; D006801:Humans; D008297:Male; D012916:Soccer / Q000502:physiology; D014443:Tyrosine / Q000008:administration & dosage / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D014443:Tyrosine