title: Effects of caffeine on exercise performance of physically fit Thoroughbreds.
abstract: OBJECTIVE
  To determine the effects of a dose of caffeine (2.5 mg/kg, IV) administered to physically fit Thoroughbreds during incremental exercise testing to fatigue on a treadmill.
  
  
  METHODS
  10 conditioned Thoroughbreds.
  
  
  METHODS
  Horses were randomly assigned to receive caffeine or a control solution. Each horse received both treatments in a crossover design with a 3-week interval between treatments. Each horse was administered caffeine (2.5 mg/kg) or an equivalent amount of a control solution IV. One hour after injection, each horse performed an incremental exercise test to exhaustion. Hematologic values, heart rate, oxygen consumption, carbon dioxide production, plasma lactate concentration, urine and serum concentrations of caffeine and metabolites, and time until exhaustion were monitored. Statistical analysis was performed by use of a mixed-effects linear model.
  
  
  RESULTS
  Significant differences in measured values when horses were treated with caffeine or the control solution were not detected.
  
  
  CONCLUSIONS
  A dose of caffeine (2.5 mg/kg, IV) appears to have no effect on any performance variable of physically fit Thoroughbreds during incremental exercise testing to fatigue.
authors.affiliation: Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610-0136, USA.
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: Savage
authors.forename: Patrick T
authors.initials: PT
authors.lastname: Colahan
authors.forename: Ian R
authors.initials: IR
authors.lastname: Tebbett
authors.forename: Brett L
authors.initials: BL
authors.lastname: Rice
authors.forename: Lester L
authors.initials: LL
authors.lastname: Freshwater
authors.forename: Christie A
authors.initials: CA
authors.lastname: Jackson
mesh_terms: D000818:Animals; D002110:Caffeine / Q000097:blood / Q000494:pharmacology* / Q000652:urine; D002245:Carbon Dioxide / Q000378:metabolism; D000697:Central Nervous System Stimulants / Q000097:blood / Q000494:pharmacology* / Q000652:urine; D018592:Cross-Over Studies; D005260:Female; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006736:Horses / Q000097:blood / Q000502:physiology* / Q000652:urine; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D010805:Physical Conditioning, Animal / Q000502:physiology*; D011897:Random Allocation
chemical_list: D000697:Central Nervous System Stimulants; D002245:Carbon Dioxide; D019344:Lactic Acid; D002110:Caffeine