Effects of various sodium bicarbonate loading protocols on the time-dependent extracellular buffering profile

Although much research has investigated the types of exercise that are enhanced with sodium bicarbonate (NaHCO3) ingestion, to date, there has been limited research on the dosage and timing of ingestion that optimizes the associated ergogenic effects. This study investigated the effects of various NaHCO3 loading protocols on the time-dependent blood-buffering profile. Eight male volunteers (age, 22.4 +/- 5.7 yr; height, 179.8 +/- 9.6 cm, body mass, 76.3 +/- 14.1 kg) completed Part A, measures of alkalosis throughout 120 minutes after ingestion of various single NaHCO3 dosages (0.3 gxkg-1, 0.2 gxkg-1, 0.1 gxkg-1, and placebo); and Part B, similar profiles after alternative NaHCO3 loading protocols (single morning dosage [SMD], single evening dosage [SED], and dosages ingested on 3 consecutive evenings [CED]). Results from Part A are as follows. Blood buffering in the 0.1 gxkg-1 condition was significantly lower than the 0.2 g.kg-1 and 0.3 gxkg-1 conditions (p < 0.002), but there was no significant differences between the 0.2 gxkg -1and 0.3 g.kg-1 conditions (p = 0.34). Although the blood buffering was relatively constant in the 0.1 and 0.2 conditions, it was significantly higher at 60 minutes than at 100 minutes and 120 minutes in the 0.3 gxkg-1 condition (p < 0.05). Results from Part B are as follows. Blood buffering for SMD was significantly higher than for SED and CED (p < 0.05). Blood buffering in the SMD condition was significantly lower at 17:00 hours than at 11:00 hours (p = 0.007). The single 0.2 and 0.3 gxkg-1 NaHCO3 dosages appeared to be the most effective for increasing blood-buffering capacity. The 0.2 gxkg-1 dosage is best ingested 40 to 50 minutes before exercise and the 0.3 gxkg-1 dosage 60 minutes before exercise.