Bicarbonate Supplements Benefit High-Intensity Exercise

A new study is consistent with the older bicarbonate literature, but extends it in a way that is much more relevant to road cycling.

Historically, the performance data on sodium bicarbonate as an exercise supplement have been most convincing for hard efforts lasting roughly 30 seconds to 12 minutes, with doses around 0.2 to 0.5 g/kg improving performance during high-intensity cycling and other high-intensity exercise.

The mechanism is extracellular buffering. Bicarbonate raises blood bicarbonate and pH, increasing the gradient for H+ movement out of working muscle and helping maintain high rates of glycolysis.

What is different here? These cyclists first rode for three hours at 95% of their gas-exchange threshold while consuming 80 g/hour of carbohydrate. They then performed sprints, a 2-minute time trial, and finally a 12-minute time trial. Bicarbonate did nothing measurable for the 6-second sprints or the 2-minute time trial, but increased 12-minute power from 239 to 251 W, about 5%.

These results support an emerging idea: bicarbonate may be useful not merely for a fresh, short high-intensity effort, but for improving a hard effort after several hours of accumulated fatigue.

The other genuinely new feature is delivery. Instead of taking a large bicarbonate dose before exercise, subjects consumed four bicarbonate-containing gels during the three-hour ride, totaling 18 g of sodium bicarbonate plus 2 g of potassium bicarbonate. Blood bicarbonate rose by about 5.8 mmol/L, yet GI problems were negligible.

Traditional bicarbonate supplementation has been limited by its GI side effects: bloating, nausea, and diarrhea. In this study, using split doses while riding minimized that problem.

The lack of significant GI problems with split dosing now makes bicarbonate a practical and potentially important supplement for racers who, after several hours of racing, might be facing a 10- to 15-minute decisive climb, sustained attack, or hard finish.

For the rest of us, there is little here to suggest any benefit beyond regular training, with intervals, and good carbohydrate replacement while on the bike.