Sodium Bicarbonate

• Bicarbonate is an endogenously produced extracellular anion, and an integral component of the body’s primary pH buffering system. During high rates of anaerobic glycolysis (inevitable during prolonged periods of intense exercise), the muscle can produce hydrogen ions (H+) in excess, which eventuates in metabolic disturbances and ultimately may contribute to fatigue. Extracellular bicarbonate facilitates the removal of these H+, and to a point, supports the body’s ability to match the high rates of energy demand required to maintain muscle contractile function during such activity.
• Numerous studies have demonstrated that endogenous bicarbonate levels can be safely and acutely increased after the oral ingestion of between 200 and 300 mg/kg body mass (BM) of sodium bicarbonate.^1,2 The additional bicarbonate is believed to attenuate the inevitable increase in intramuscular H+, synonymous with high-intensity exercise, although the physiologic mechanisms directly responsible for performance augmentation in humans are unclear.³
  • Meta-analyses have reported that supplementation at these levels can result in an approximate 2 to 3% improvement across a variety of performance measurements (e.g. power, speed, work capacity, time to failure) during both single and repeated bouts of high-intensity exercise typically lasting 1-10 minutes in duration.^4,5,6
  • The 2018 International Olympic Committee Sports Nutrition Consensus Statement recommendations suggest that sodium bicarbonate is one of five dietary supplements that consistently improves performance in the elite athlete.⁷

• The most commonly available and economical source of sodium bicarbonate is the household/baking product baking soda. However, most athletes find ingesting sodium bicarbonate mixed in water or even diluted with cordial to be unpalatably salty.
  • Alternative powder forms of sodium bicarbonate are also found in urinary alkalinisers such as Ural Effervescent Powder (1.75 g per sachet), which also contain other ingredients (e.g. carbohydrates, citric acid and most notably sodium citrate (630 mg)).
• A more palatable delivery of sodium bicarbonate can be provided in tablet or capsule form (e.g. SodibicTM at 840 mg per tablet). While less convenient, filling enteric capsules (e.g. Capsugel®) with either bicarbonate powder or aqueous solution may also be a viable option. This capsule casing is proposed to resist the acidity of the stomach, instead dissolving in the intestine, which may also reduce gastro-intestinal (GI) symptoms of bicarbonate ingestion.⁸
• Transdermal delivery of sodium bicarbonate is commercially available (Amp Human®), however more research is needed on the efficacy of this delivery system.⁹

• Current ingestion recommendations are to consume between 200 to 400 mg/kg BM with a small, carbohydrate dense meal (~1.5 g/kg BM CHO) approximately 120 to 150 min prior to exercise.⁷
  • Broad ingestion recommendations should only serve as a starting point, as several practical issues associated with sodium bicarbonate may influence the efficacy of this supplement such as ingestion timing, individual tolerability and/or susceptibility to GI distress, and the potential co-ingestion of other supplements.^10,11,12 Where practicable, monitoring of blood bicarbonate concentrations and pH in response to sodium bicarbonate ingestion, warm-up and event are also strongly encouraged. Experience at the AIS has shown that this frequently uncovers issues that can be manipulated to enhance outcomes for the individual athlete.
  • There is some preliminary evidence that timing an individual’s ingestion protocol in order to commence competition at their individualized peak blood buffering capacity may improve performance. However, this requires periodically measuring blood bicarbonate changes over multiple testing sequences.¹⁰
  • If individualizing the ingestion strategy is not feasible, ingestion at the higher end of the recommended doses (e.g. 300 to 400 mg/kg BM) 2 to 3 hours pre-competition should significantly elevate blood buffering capacity to levels presumed to be ergogenic (~ 5 – 6 mmol/L increase) with effects lasting for 3 to 4 hours. Co-ingestion with a small high carbohydrate meal supports blood alkalosis while reducing the occurrence of GI symptoms. This method of delivery would allow more time for those athletes susceptible to GI distress (which typically peaks 90 min post-ingestion) to resolve any potential issues before competition.
• There is good evidence for the use of bicarbonate by athletes competing in high-intensity activity lasting from 1 to 7 minutes – for example, swimming, rowing and middle-distance running events.⁴
  • It should be recognized that in many events of this type, competition may require the athlete to undertake several events within a relatively short timeframe, or to compete later the same day. This competition schedule may require an adjustment of sodium bicarbonate loading protocols to account for repeated events. In this example, “split” strategies of loading may be incorporated around time constraints, or alternatively using a “top-up” approach with smaller amounts (e.g. 100 mg/kg BM) consumed once or twice over the remainder of the competition timeframe.⁷ As there is no published data on the efficacy of split- or top-up approaches, this would need to be trialed in training.
  • Alternatively, a bicarbonate supplementation protocol involving multiple divided doses over several days before competition may be appropriate. This involves a higher daily bicarbonate dose (500mg/kg BM) in several even doses (e.g., 100mg/ kg BM with 3 main meals and ² snacks) up to 5 days before competition, as well as the day of competition.¹³
• Over the past decade, there have been a few studies reporting benefits in physical performance improvements in skill-based sports requiring prolonged, repeated high-intensity efforts (e.g. team, racquet and combat sports).
  • Given this evidence, high-intensity events of up to an hour which are conducted at work rates just below an individual’s anaerobic/lactate threshold may also be relevant for sodium bicarbonate supplementation. In this instance, the additional buffering capacity may support the athlete’s ability to increase their pace/work output for strategic periods (e.g. surges, sprint finishes).
• There is a growing body of evidence that suggests increases in aerobic adaptability (e.g. increased oxidative and mitochondrial function) are augmented with sodium bicarbonate supplementation during blocks of interval training sessions.^14,15
  • There is also evidence supporting fatigue attenuation after acute sodium bicarbonate supplementation in measures of explosive power (e.g. rate of force development).^16,17
• There have been studies investigating the efficacy of co-ingestion with other supplements (e.g. caffeine, creatine, beta-alanine, ketone bodies), however presently the evidence is equivocal (with the exception of sodium bicarbonate appearing to counteract the acidity induced by ketosis).

• The major side effect associated with sodium bicarbonate supplementation is gastrointestinal distress, with symptoms including nausea, stomach pain, diarrhoea and vomiting. This is a serious practical consideration for athletes in a competition setting, and this may counteract the potential performance benefits from enhanced buffering.
  • Research undertaken at the AIS systematically studied a series of sodium bicarbonate supplementation protocols, varying the time taken to consume the load (spreading it over 30 to 60 mins), the form of the delivery (flavoured powder or capsules) and the consumption of various amounts of fluid or food with the sodium bicarbonate.4 Of the protocols tested, the best strategy to optimise blood bicarbonate levels and to reduce the occurrence of GI symptoms was to consume capsules in a spread-out protocol, commencing 120 to 150 min before the start of exercise and, if practical, at the same time as consuming a meal composed of carbohydrate-rich food choices and some fluid.
• It is generally advised to ingest sodium bicarbonate capsules or dissolvable powder with sufficient fluid to decrease the risk of hyperosmotic diarrhea (~ 10ml/kg BM).
  • Given the significant amount of fluid intake recommended to alleviate GI distress, consideration may be given toward the additional weight gain this might induce for weight-dependent sports.
• Repeated use of acute loading protocols (e.g. heats and finals in a single or multi-day competition) may require individualized attention to exacerbate the risk of side-effects. This may be reduced if the athlete uses lower doses on subsequent occasions to compensate for bicarbonate remaining in the body.
• Anecdotal feedback from athletes also suggests that those unfamiliar with sodium bicarbonate supplementation may need to experience the supplement on a number of occasions prior to competition, due to the potential for impaired perceptive feedback from the working muscles.
• Changes in urinary pH are expected following bicarbonate supplementation. If an athlete is selected for a drug test, they may need to wait several hours before urinary pH returns to the levels that are acceptable to drug testing authorities. This may cause some disruption to the athlete’s routine.

Gatorade Sports Science Institute www.gssiweb.org/en/sports-science-exchange/Article/sse-124-buffers-and-their-role-in-the-nutritional-preparation-of-athletes, opens in a new tab

Supplement safety information www.sportintegrity.gov.au/what-we-do/anti-doping/supplements-sport, opens in a new tab

1. Price M, Singh M. (2008). Time course of blood bicarbonate and pH three hours after sodium bicarbonate ingestion. Int J Sports Physiol Perform, 3, 240-242.
2. Siegler JC, Midgley AW, Polman RCJ, Lever R. (2010). Effects of various sodium bicarbonate loading protocols on the time-dependent extracellular buffering profile. J Strength Cond Res, 24(9), 2551-2557.
3. Siegler JC, Marshall PWM, Bishop D, Shaw G, Green G. (2016). Mechanistic insights into the efficacy of sodium bicarbonate supplementation to improve athletic performance. Sports Medicine – Open, 2, 41.
4. Carr AJ, Hopkins WG, Gore CJ. (2011). Effects of acute alkalosis and acidosis on performance: a meta-analysis. Sports Med, 41(10), 801-814.
5. Peart DJ, Siegler JC, Vince RV. (2012). Practical recommendations for coaches and athletes: a meta-analysis of sodium bicarbonate use for athletic performance. J Strength Cond Res, 26(7), 1975-1983.
6. Hadzic M, Eckstein ML, Schugardt M. (2019). The impact of sodium bicarbonate on performance in response to exercise duration: a systematic review. J Sports Sci Med, 18(2), 271-281.
7. Maughan RJ, Burke LM, Dvorak J, Larson-Meyer DE, Peeling P et al. (2018). IOC consensus statement: dietary supplements and the highperformance athlete. Br J Sports Med, 52(7), 439-455.
8. Hilton NP, Leach NK, Sparks SS, Gough LA, Craig MM, Deb SK, McNaughton LR. A novel ingestion strategy for sodium bicarbonate supplementation in a delayed-release form: a randomized crossover study in trained males. Sports Med – Open, 5, 4.
9. McKay A, Peeling P, Binnie M, Goods P, Sim M, Cross R, Siegler J. (2021). Topical sodium bicarbonate: No improvement in blood buffering capacity or exercise performance. Int J Sports Physiol Perform. (ahead of print)
10. Heibel AB, Perim PHL, Oliveira LF, McNaughton LR, Saunders B. (2018). Time to optimize supplementation: modifying factors influencing the individual responses to extracellular buffering agents. Front Nutr, 5, 35.
11. Boegman S, Stellingwerff T, Shaw G, Clarke N, Graham K, Cross R, Siegler JC. (2020). The impact of individualizing sodium bicarbonate supplementation strategies on world-class rowing performance. Front Nutur, 7, 138.
12. de Oliveira LF, Saunders B, Yamaguchi G, Swinton P, Artioli GG. (2020). Is individualization of sodium bicarbonate ingestion based on time to peak necessary? Med Sci Sports Exerc, ahead of print.
13. McNaughton L, Backx K, Palmer G, Strange N. (1999). Effects of chronic bicarbonate ingestion on the performance of high-intensity work. Eur J Appl Physiol, 80, 333-336.
14. Edge J, Bishop D, Goodman C. (2006). Effects of chronic NaHCO3 ingestion during interval training on changes to muscle buffer capacity, metabolism, and short-term endurance performance. J Appl Physiol, 101, 918-925.
15. Percival ME, Martin BJ, Gillen JB, Skelly LE, MacInnis MJ, Green AE, Tarnopolsky MA, Gibala MJ. (2015). Sodium bicarbonate ingestion augments the increase in PGC-1 m RNA expression during recovery from intense interval exercise in human skeletal muscle. J Appl Physiol, 119, 1303-1312.
16. Siegler JC, Marshall PW, Raftry S, Brooks C, Dowswell B, Romero R, Green S. (2013). The differential effect of metabolic alkalosis on maximum force and rate of force development during repeated, high-intensity cycling. J Appl Physiol, 115, 1634-1640.
17. Siegler JC, Marshall PW, Finn H, Cross R, Mudie K. (2018). Acute attenuation of fatigue after sodium bicarbonate supplementation does not manifest into greater training adaptations after 10-weeks of resistance training exercise. PLOS One, 13, 5.