One purpose of the present study was to evaluate the effect of elevating serum bicarbonate concentration more than had been achieved in previous studies without inducing potentially ergolytic GI distress. In order to do so, a modified SB ingestion protocol (ModSB) of 4 progressively larger doses (110 mg·kg-1 - 200 mg·kg-1) was administered. It was hypothesized that ModSB would significantly elevate serum bicarbonate concentration to a greater extent than would an acute SB ingestion protocol (AcuteSB).

This study was also designed to corroborate the results of previous studies regarding the ergogenic effects of sodium bicarbonate ingestion. Most studies have administered sodium bicarbonate in solutions, which would make the participants aware of the substance ingested due to the distinctive flavor of SB, possibly inducing a placebo effect. All doses in the present study were administered in gelatin capsules to mask the flavor of the ingested substances, maintaining participant blindness to the procedure.

Blood samples were collected at baseline and following placebo (CaCO3), acute sodium bicarbonate ingestion, and modified sodium bicarbonate ingestion to determine the effects of the ingestion protocols on serum bicarbonate, sodium and lactate concentrations, as well as on serum pH and blood hematocrit. The study design was a randomized double-blind crossover.

Inclusion Criteria:

• Peak oxygen consumption greater than 60 ml·kg-1·min-1 (men) or 50 ml·kg-1·min-1 (women)
• Currently training; defined as at least 5 days·week-1 of running
• Elite-level performance (750 or more points on the International Associations of Athletics Federations Scoring Table) for an 800m-5000m race during the preceding 6 months.

Exclusion Criteria:

-

The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Opaque gelatin capsules