Effects of acute alkalosis and acidosis on performance: A meta-analysis

Journal Title (Medline/Pubmed accepted abbreviation): Sports Med.
Year: 2011
Volume: 41
Issue: 10
Page numbers: 801-814

Summary of the article/Key findings:

      The acidity/alkalinity of the blood and intracellular muscle compartments may affect performance and can be regulated through supplementation. Bicarbonate is the natural buffer in the blood and, due to acid production during exercise, athletes attempt to increase the buffering capacity of the blood and/or the pH of the blood to deter acid build up. The purpose of this investigation was to globally analyze all of the studies to date (2009) that investigated the effects of pH and/or pH or buffer regulators on performance. Sodium bicarbonate and sodium citrate are alkaline supplements and ammonium chloride is an acidic supplement. In total, 59 studies that met the inclusion criteria were analyzed.  

Performance measures:
  • Sodium bicarbonate, ingested at a dose of 3.5 mmol/kg body mass, led to moderately increased speed while performing 6 × 1 min sprints. Under average test conditions, performance was improved about 2%.
  • There was not conclusive evidence that sodium citrate improved performance.
  • Ammonium chloride generally had a moderate negative effect on performance.

Physiological measures:
  • Blood pH was clearly elevated with sodium bicarbonate supplementation.
  • There was a moderate positive correlation between blood pH at the start of exercise and performance when assessing both sodium bicarbonate and ammonium chloride studies. Data from sodium citrate studies were not conclusive.

     Sodium citrate is a base that has three negative charges, whereas sodium bicarbonate only has one. Sodium citrate has also been shown to increase concentrations of bicarbonate in the blood (and, therefore, theoretically, buffering capacity). However, the authors predict that sodium citrate may need to be taken at least 180 min before exercise to exert its effect (most studies only allowed 60-90 min). It was not possible to pool all of the gastrointestinal disturbance data from all of the studies for this analysis, but the improvements in performance with sodium bicarbonate suggest that the disturbances were not severe enough to negate or confound performance benefits. 

Key practice applications:

The authors recommend sodium bicarbonate supplementation at 0.3 g/kg body weight (about 25 g for a 185 lb person) to increase performance in high intensity, short duration exercises. The authors do not recommend sodium citrate based on available data, but think that further investigations are warranted. In general, it would be prudent to avoid ammonium chloride (or other highly acidic beverages) before exercise, since a decrease in pH may be associated with a decrease in performance.


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