Purpose: 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, [latin capital V with dot above]O2peak = 45.3 +/- 3.1 mL[middle dot]kg-1[middle dot]min-1) volunteered for the study, which had received ethics clearance. The athletes ingested two doses of either 0.2 g[middle dot]kg-1 of NaHCO3 or 0.138 g[middle dot]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 ~2-min blocks: all-out 4-s sprint, 100 s of active recovery at 35% [latin capital V with dot above]O2peak, 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. [latin capital V with dot above]O2 was also recorded at regular intervals throughout the IST. Results: Resting plasma bicarbonate concentration ([HCO3-]) averaged 22.6 +/- 0.9 mmol[middle dot]L-1, and at 90 min postingestion was 21.4 +/- 1.5 and 28.9 +/- 2.8 mmol[middle dot]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 preingestion. 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.
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