title: Effects of pre-exercise alkalosis on the decrease in VO2 at the end of all-out exercise.
abstract: OBJECTIVE
  This study determined the effects of pre-exercise sodium bicarbonate ingestion (ALK) on changes in oxygen uptake (VO2) at the end of a supramaximal exercise test (SXT).
  
  
  METHODS
  Eleven well-trained cyclists completed a 70-s all-out cycling effort, in double-blind trials, after oral ingestion of either 0.3 g kg(-1) of sodium bicarbonate (NaHCO3) or 0.2 g kg(-1) body mass of calcium carbonate (PLA). Blood samples were taken to assess changes in acid-base balance before the start of the supramaximal exercise, and 0, 5 and 8 min after the exercise; ventilatory parameters were also measured at rest and during the SXT.
  
  
  RESULTS
  At the end of the PLA trial, which induced mild acidosis (blood pH = 7.20), subjects presented a significant decrease in VO2 (P < 0.05), which was related to the amplitude of the decrease in minute ventilation (VE) during the SXT (r = 0.70, P < 0.01, n = 11). Pre-exercise metabolic alkalosis significantly prevented the exercise-induced decrease in VO2 in eleven well-trained participants (PLA:12.5 ± 2.1 % and ALK: 4.9 ± 0.9 %, P < 0.05) and the decrease in mean power output was significantly less pronounced in ALK (P < 0.05). Changes in the VO2 decrease between PLA and ALK trials were positively related to changes in the VE decrease (r = 0.74, P < 0.001), but not to changes in power output (P > 0.05).
  
  
  CONCLUSIONS
  Pre-exercise alkalosis counteracted the VO2 decrease related to mild acidosis, potentially as a result of changes in VE and in muscle acid-base status during the all-out supramaximal exercise.
authors: French National Institute of Sports (INSEP), 11 Tremblay Avenue, 75012, Paris, France. claire.thomas@univ-evry.fr.|STAPS Department, University of Evry Val d'Essonne, François Mitterrand Boulevard, 91025, Evry, France. claire.thomas@univ-evry.fr.
authors: Claire
authors: C
authors: Thomas
authors: French National Institute of Sports (INSEP), 11 Tremblay Avenue, 75012, Paris, France.
authors: Rémi
authors: R
authors: Delfour-Peyrethon
authors: Institute of Sport, Exercise and Active Living (ISEAL), College of Sport and Exercise Science, Victoria University, Melbourne, Australia.
authors: David J
authors: DJ
authors: Bishop
authors: EuroMov: Movement to Health, University of Montpellier, Montpellier, France.
authors: Stéphane
authors: S
authors: Perrey
authors: Laboratory "Adaptations physiologiques à l'exercice et réadaptation à l'effort" (EA-3300), University of Picardie Jules Verne, UFR-STAPS, 80025, Amiens Cedex, France.
authors: Pierre-Marie
authors: PM
authors: Leprêtre
authors: Laboratory "Motricité, Interactions, Performance" (EA 4334), University of Nantes, 44000, Nantes, France.
authors: Sylvain
authors: S
authors: Dorel
authors: French National Institute of Sports (INSEP), 11 Tremblay Avenue, 75012, Paris, France.
authors: Christine
authors: C
authors: Hanon
mesh_terms: D000328:Adult; D000471:Alkalosis / Q000097:blood* / Q000503:physiopathology; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects; D005082:Physical Exertion / Q000187:drug effects / Q000502:physiology; D017693:Sodium Bicarbonate / Q000494:pharmacology; D013997:Time Factors; D055815:Young Adult
chemical_list: D017693:Sodium Bicarbonate
keywords: Acid–base status; Fatigue; High-intensity exercise; Minute ventilation; Oxygen uptake; Sodium bicarbonate