Bicarbonate loading

Bicarbonates are important part of the buffering system necessary to maintain the acid-base balance of body fluids. Scientists naturally began to investigate whether performance in highly anaerobic events, in which large amounts of lactic acid are formed, could be improved by enhancing the body’s buffering capacity through elevation of the blood’s bicarbonate concentrations, a process called bicarbonate loading.

Proposed ergogenic benefits

By ingesting agents that increase the bicarbonate concentrations in the blood plasma, such as sodium bicarbonate(baking soda), subjects can increase blood pH, making the blood more alkaline. It was proposed that increasing plasma bicarbonate levels would provide additional buffering capacity, allowing higher concentrations of lactate in the blood. Theoretically, this could delay the onset of fatique in short-term, all-out anaerobic work, such as all-out sprinting.

Proven effects

Oral intake of sodium bicarbonate elevates plasma bicarbonate concentrations. However, this has little effect on intracellular concentrations of bicarbonate in muscle. Therefore, the potential benefits of bicarbonate ingestion were thought to be limited to anaerobic bouts of exercise lasting longer than 2 min, because bouts less than 2 min would be too brief to allow many hydrogen ions(H⁺, from the lactic acid) to diffuse out of the muscle fibers into the extracellular fluid where they could be buffered.

In 1990, however, Roth and Brooks described a cell membrane lactate transporter that operates in response to the pH gradient. Increasing the extracellular buffering capacity by ingesting bicarbonate increases the extracellular pH, which in turn increases transport of lactate from the muscle fiber via this membrane transporter to the blood plasma and other extracellular fluids. This should improve anaerobic performances even for events briefer than 2 min. Although the theory proposing bicarbonate ingestion as an ergogenic aid for anaerobic performance is sound, the research literature is, again, conflicting. However, Linderman and Fahey, in their review of the literature, found several important patterns in the research that might explain these conflicts. They concluded that bicarbonate ingestion had little or no effect on performances of less than 1 min or of more than 7 min but that for performances between 1 and 7 min, the ergogenic effects were evident. Furthermore, they found that the dose was important. Most studies that used a dose of 300 mg/kg of body mass showed a benefit, whereas most studies of lower dosage showed little or no benefit. Thus, it appears that bicarbonate ingestion of 300 mg/kg of body mass can enhance the performance of all-out, maximal anaerobic activities of 1 to 7 min duration.

In one study, blood bicarbonate concentrations were artificially elevated by bicarbonate ingestion before and during five sprint-cycling bouts, each lasting 1 min. Performance on final trial improved 42%! This elevation in blood bicarbonate levels reduced the concentration of free H⁺ both during and after exercise, thereby elevating blood pH. The authors concluded that in addition to improving buffering capacity, the extra bicarbonate appeared to speed the removal of H⁺ ions from the muscle fibers, thereby reducing the decrease in intracellular pH. Six years later, in 1990, Roth and Brooks reported the presence of a lactate transporter in the muscle cell membrane, and that also worked precisely.

Risks of bicarbonate loading

Although sodium bicarbonate has long been used as a remedy for indigestion, many authors studying bicarbonate loading have reported severe gastrointestinal discomfort in some of their subjects, including diarrhea, cramps, and bloating, from high doses of bicarbonate. These symptoms can be prevented if one ingests as much water as desired and divides the total bicarbonate dosage of at least 300mg/kg of body mass into five equal parts over a 1 to 2h period. Also, several studies have shown sodium citrate to have similar effects on buffering capacity and performance without gastrointestinal discomfort.