Background: The aim of the present study was to investigate the effects of sodium bicarbonate supplementation on anaerobic performance and some plasma metabolites.Material/Methods: 16 young male athletes (age 20.58±3.25, Height 175.33±2.48 cm and BMI 21.57±2.68 kg/m2) participated in two 400 m running sessions one hour following sodium bicarbonate or placebo (calcium bicarbonate) supplementation with the counterbalanced order. There were three blood sampling phases (resting condition, 30 min after supplementation and 2 min after 400 m running) in both of the sessions and the blood pH; ammonia, lactate, and HCO--3 levels were measured.Results: The results showed that running time in the sodium bicarbonate session was significantly lower (57.41±0.11 sec) than the placebo (59.01±0.78 sec) session (P<0.05). The blood HCO--3 levels (29.53±2.64 mmol/L) increased with respect to the resting values (23.13±1.84 mmol/L) with sodium bicarbonate administration; however, it decreased to the pre-exercise level (20.45±1.92 mmol/L) after running (P<0.05). The HCO--3 levels (17.89±2.48 mmol/L) also decreased under the resting values (23.31±2.15 mmol/L) after running in the placebo session (P<0.05). Significant increases were observed in blood lactate levels in both of the sessions; however, blood pH significantly decreased only in the placebo session (P<0.05).Conclusions: It can be concluded that alkalosis can be considered as an ergogenic method and can prevent a decrease in blood HCO--3 during high intensity exercise.