Acute versus chronic sodium bicarbonate ingestion and anaerobic work and power output

Background. The aim of this study was to compare and contrast the effects of acute versus chronic sodium bicarbonate ingestion. Methods. Participants: eight male, (mean±SE): age, 20.8±0.4 yrs; height, 179.6±0.6 cm; body mass, 79.4±0.85 kg, ∑7skf, 48.6±4.8 mm, V̇O_2max=55.9±0.8 ml·kg·1·min^-1) volunteer subjects, ingested NaHCO₃ in either a dose of 0.5 g.kg-1 body mass acutely or the same dose daily over a period of six days in order to determine whether there were any differences in performance of 90 sec maximal cycling ergometry. Intervention: after subjects undertook an initial control (C) test session, all were then randomly assigned to one of two groups, acute or chronic NaHCO₃ ingestion. Subjects in the acute ingestion (AI) group completed their supplemented test on day one, and then on the following day. Chronic ingestion (CI) subjects completed the test after one day of chronic ingestion as well as following six days of bicarbonate ingestion. Following ten days rest, subjects repeated the protocol in the opposite group. Measures: blood samples were taken pre- and postingestion, daily, and pre- and postexercise and were analysed for, pH, Base excess (BE), HCO₃^-, PO₂, PCO₂, Na⁺, K⁺, Cl^-, and lactate. Results. Both the chronic (CI) and acute ingestion (AI) groups were significantly different to the control (C) value (p<0.001 and p<0.05, respectively). Conclusions. We would suggest using chronic ingestion as a means to improve high intensity work rather than the acute ingestion of sodium bicarbonate. The ingestion of sodium bicarbonate, over a period of six days, significantly improved work output two days after bicarbonate ingestion ceased.