Effect of ingested sodium bicarbonate on muscle force, fatigue, and recovery

The influence of acute ingestion of NaHCO₃ on fatigue and recovery of the quadriceps femoris muscle after exercise was studied in six healthy male subjects. A bicycle ergometer was used for exercising under three loading conditions: test A, load corresponding to maximal oxygen consumption; test B, load in test A + 17%; test C, load in test B but performed 1 h after acute ingestion of NaHCO₃. Functional electrical stimulation (FES) was applied to provoke isometric contraction of the quadriceps femoris. The resulting knee torque was monitored during fatigue (2-min chronic FES) and recovery (10-s FES every 10 min, for 40 min). Quadriceps torques were higher in the presence of NaHCO₃ (P < 0.05): with NaHCO₃ the peak, residual; and recovery (after 40 min) normalized torques were, respectively, 0.68 ± 0.05 (SD), 0.58 ± 0.05, and 0.73 ± 0.05; without NaHCO₃ the values were 0.45 ± 0.04, 0.30 ± 0.06, and 0.63 ± 0.06. The increased torques obtained after acute ingestion of NaHCO₃ indicate the possible existence of improved nonoxidative glycolysis in isometric contraction, resulting in reduced fatigue and enhanced recovery.