Effects of induced metabolic alkalosis on prolonged intermittent-sprint performance.
OBJECTIVE
Previous studies have shown that induced metabolic alkalosis, via sodium bicarbonate (NaHCO3) ingestion, can improve short-term, repeated-sprint ability. The purpose of this study was to assess the effects of NaHCO3 ingestion on a prolonged, intermittent-sprint test (IST).


METHODS
Seven female team-sport athletes (mean +/- SD: age = 19 +/- 1 yr, VO2peak = 45.3 +/- 3.1 mL x kg(-1) x min(-1)) volunteered for the study, which had received ethics clearance. The athletes ingested two doses of either 0.2 g x kg(-1) of NaHCO3 or 0.138 g x kg(-1) of NaCl (placebo), in a double-blind, random, counterbalanced order, 90 and 20 min before performing the IST on a cycle ergometer (two 36-min "halves" of repeated approximately 2-min blocks: all-out 4-s sprint, 100 s of active recovery at 35% VO2peak, and 20 s of rest). Capillary blood samples were drawn from the ear lobe before ingestion, and before, during, and after each half of the IST. VO2 was also recorded at regular intervals throughout the IST.


RESULTS
Resting plasma bicarbonate concentration ([HCO3-]) averaged 22.6 +/- 0.9 mmol x L(-1), and at 90 min post-ingestion was 21.4 +/- 1.5 and 28.9 +/- 2.8 mmol x L-1 for the placebo and NaHCO3 conditions, respectively (P < 0.05). Plasma [HCO3-] during the NaHCO3 condition remained significantly higher throughout the IST compared with both placebo and pre-ingestion. There was a trend toward improved total work in the second (P = 0.08), but not first, half of the IST after the ingestion of NaHCO3. Furthermore, subjects completed significantly more work in 7 of 18 second-half, 4-s sprints after NaHCO3 ingestion.


CONCLUSIONS
The results of this study suggest that NaHCO3 ingestion can improve intermittent-sprint performance and may be a useful supplement for team-sport athletes.
Bishop
David
D
Team Sport Research Group, School of Human Movement and Exercise Science, The University of Western Australia, Crawley, WA, Australia. dbishop@cyllene.uwa.edu.au
Claudius
Brett
B
D000328:Adult; D000471:Alkalosis / Q000139:chemically induced / Q000503:physiopathology*; D001639:Bicarbonates / Q000097:blood; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D016552:Ergometry; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000097:blood; D010101:Oxygen Consumption / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012420:Running / Q000502:physiology*; D017693:Sodium Bicarbonate / Q000494:pharmacology*
D001639:Bicarbonates; D019344:Lactic Acid; D017693:Sodium Bicarbonate