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PRICE, M., P. MOSS, and S. RANCE. Effects of Sodium Bicarbonate Ingestion on Prolonged Intermittent Exercise. Med. Sci. Sports Exerc., Vol. 35, No. 8, pp. 1303-1308, 2003.

Purpose: The aim of this study was to determine the effects of sodium bicarbonate ingestion on prolonged intermittent exercise and performance.

Methods: Eight healthy male subjects (mean /- SD: age 25.4 /- 6.4 yr, mass 70.9 /- 5.1 kg, height 179 /- 7 cm, [latin capital V with dot above]O2max 4.21 /- 0.51 L[middle dot]min-1) volunteered for the study, which had received ethical approval. Subjects undertook two 30-min intermittent cycling trials (repeated 3-min blocks; 90 s at 40% [latin capital V with dot above]O2max, 60 s at 60% [latin capital V with dot above]O2max, 14-s maximal sprint, 16-s rest) after ingestion of either sodium bicarbonate (NaHCO3; 0.3 g[middle dot]kg-1) or sodium chloride (NaCl; 0.045 g[middle dot]kg-1). Expired air, blood lactate (BLa), bicarbonate (HCO3-), and pH were measured at rest, 30 and 60 min postingestion, and during the 40% [latin capital V with dot above]O2max component of exercise (4, 10, 16, and 29 min).

Results: After ingestion, pH increased from rest to 7.46 /- 0.03 and 7.40 /- 0.01 for NaHCO3 and NaCl, respectively (main effect for time and trial; P < 0.05). Values decreased at 15 min of exercise to 7.30 /- 0.07 and 7.21 /- 0.06, respectively, remaining at similar levels until the end of exercise. BLa peaked at 15 min (12.03 /- 4.31 and 10.00 /- 2.58 mmol[middle dot]L-1, for NaHCO3 and NaCl, respectively; P > 0.05) remaining elevated until the end of exercise (P < 0.05). Peak power expressed relative to sprint 1 demonstrated a significant main effect between trials (P < 0.05). Sprint 2 increased by 11.5 /- 5% and 1.8 /- 9.5% for NaHCO3 and NaCl, respectively. During NaHCO3, sprint 8 remained similar to sprint 1 (0.2 /- 17%), whereas a decrease was observed during NaCl (-10.0 /- 16.0%).

Conclusion: The results of this study suggest that ingestion of NaHCO3 improves sprint performance during prolonged intermittent cycling.

(C)2003The American College of Sports Medicine