The effects of NaHCO3 and NaCl loading on hematocrit and high-intensity cycling performance

Inconsistent findings regarding the benefits of sodium bicarbonate (NaHCO₃) loading on exercise performance may be related to the use of sodium chloride (NaCl) as placebo substances. It has been postulated that the sodium content of both substances may contribute to performance benefits. The purpose of this study was to compare NaHCO₃ and NaCl to a physically inert placebo by evaluating the effect of acute loading on high-intensity cycling performance. Eight well-trained cyclists (age = 24 ± 7 yrs; mass = 77 ± 9 kg; VO₂ peak = 59.8 ± 8.6 mL•kg-1•min-1) completed a 2-min performance test on a cycling ergometer after either NaHCO₃ loading (SB), NaCl loading (SC), or placebo loading (D) in a randomized, double-blind design. Blood samples were taken pre- and post-loading and pre- and post-performance test to analyze hematocrit levels. The SB trial produced significantly higher (P < 0.05) mean power (watts) in the 2-min test (514.9 ± 49.7) when compared to the SC and D trials (504.3 ± 51.0 and 498.7 ± 50.6, respectively), with no significant difference between SC and D trials (P > 0.05). There were no significant differences in hematocrit levels at any timepoint between the 3 trials (P > 0.05). These findings indicate that NaHCO₃ loading produced significant performance enhancement when compared to both NaCl and a placebo substance.