The time course for changes in plasma [h+] after sodium bicarbonate ingestion.

Numerous studies have demonstrated that induced alkalosis through ingestion of a sodium bicarbonate (NaHCO 3 ) solution can enhance performance during maximalintensity exercise of varying durations, as well as maintain performance during high-intensity intermittent exercise. Several studies have investigated the effect of dose ingested on subsequent exercise performance. For example, Horswill et al demonstrated that doses of less than 0.2 g/kg were ineffective in improving performance during 2 minutes of maximal cycle exercise, whereas Wilkes et al improved run performance of similar duration using a dose of 0.3 g/kg. Most studies have used a dose of 0.3 g/kg, and this seems to be the largest that can safely be consumed without an unacceptable risk of side effects of gastrointestinal distress. Although there is some consensus with regard to the optimal dose of NaHCO 3 that should be ingested, the timing of ingestion in relation to the start of exercise seems to vary from study to study. Matson and Tran conducted a meta-analysis and found that studies that produced a large effect size in terms of improved exercise performance were associated with larger doses (0.278 ± 0.60 g/kg) and produced greater decreases in preexercise plasma [H] and greater increases in [H] after exercise than in studies that used lower doses (0.236 ± 0.70 g/kg). Because it appears that the magnitude of the induced change in plasma [H] determines the success or lack thereof of NaHCO 3 as an ergogenic aid, it is necessary to establish the time course for changes in plasma [H] after ingestion of the most commonly reported dose. This will allow identification of the optimal time of ingestion in relation to the subsequent maximum change in plasma [H] and thus the timing of the commencement of exercise.