title: Acute L-arginine supplementation has no effect on cardiovascular or thermoregulatory responses to rest, exercise, and recovery in the heat.
abstract: OBJECTIVE
  To investigate the effect of acute L-arginine (L-ARG) supplementation on cardiovascular and thermoregulatory responses to rest, exercise, and recovery in the heat.
  
  
  METHODS
  Eight healthy men (age 27 ± 6 years; stature 176 ± 6 cm; body mass 76 ± 4 kg; maximal power output 237 ± 39 W) participated in a double-blind, crossover study, attending the laboratory for two experimental trials. On each occasion, participants consumed 500 ml of a black currant-flavoured cordial beverage 30 min before completing a 90 min experiment in the heat (35 °C and 50% rh). The experiment consisted of 30 min of seated rest, followed by 30 min submaximal cycling (60% maximal power output) and 30 min passive seated recovery. On one visit the drink contained 10 g of dissolved L-ARG while on the other visit it did not.
  
  
  RESULTS
  L-ARG supplementation increased plasma L-ARG concentrations (peak +223 ± 80% after 60 min of the 90 min experiment); however, supplementation had no effect on rectal temperature, mean skin temperature, heart rate, arterial pressure, forearm skin vascular conductance, oxygen consumption or sweat loss at rest, during exercise, or during recovery in the heat (p > 0.05).
  
  
  CONCLUSIONS
  Acute ingestion of 10 g L-ARG supplementation failed to elicit any changes in the cardiovascular or thermoregulatory responses to active or passive heat exposure in young, healthy males.
authors.affiliation: Department of Life Sciences, University of Roehampton, London, SW15 4JD, England, UK. chris.tyler@roehampton.ac.uk.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Tyler
authors.affiliation: Department of Life Sciences, University of Roehampton, London, SW15 4JD, England, UK.
authors.forename: Thomas R M
authors.initials: TR
authors.lastname: Coffey
authors.affiliation: Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada.
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Hodges
mesh_terms: D000064:Acclimatization / Q000187:drug effects*; D000328:Adult; D001120:Arginine / Q000008:administration & dosage / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects*; D019587:Dietary Supplements; D015444:Exercise; D006339:Heart Rate / Q000187:drug effects*; D006358:Hot Temperature; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects; D013546:Sweating / Q000187:drug effects*
chemical_list: D001120:Arginine
keywords: Heat loss; Nitric oxide; Skin blood flow; Thermoregulation; Vasodilation