Effects of sodium bicarbonate ingestion on prolonged intermittent exercise

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, VO_2max 4.21 ± 0.51 L·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% VO_2max, 60 s at 60% VO_2max 14-s maximal sprint, 16-s rest) after ingestion of either sodium bicarbonate (NaHCO₃; 0.3 g·kg^-1) or sodium chloride (NaCl; 0.045 g·kg^-1). Expired air, blood lactate (BLa), bicarbonate (HCO₃^-), and pH were measured at rest, 30 and 60 min postingestion, and during the 40% VO_2max 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·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.