What Is Sodium Bicarbonate and How Does It Work?

Sodium bicarbonate (NaHCO3), often simply called bicarb, is a widely researched ergogenic aid in performance sport, which acts as an extracellular buffer (Siegler et al, 2016). It is sometimes called bicarbonate of soda, and is literally the same compound as in baking soda, found in store cupboards across the world, but when used correctly can be just the performance booster you need.

During high-intensity exercise, the rate of energy demand exceeds the ability of the aerobic system to supply ATP (). As a result, muscle cells rely more heavily on anaerobic glycolysis, which rapidly breaks down glucose to produce ATP. This process leads to production of lactic acid, and the associated accumulation of hydrogen ions (H⁺) as lactic acid dissociates into lactate and hydrogen ions (Brooks, 2020). This reaction causes a decrease in muscle pH, a condition often referred to as muscle acidosis which compromises muscle function. The lower pH (acidity) can interfere with enzyme activity, calcium handling, and the interaction between actin and myosin, contributing to muscular fatigue and a reduced ability to generate force (Robergs et al, 2004).

How bicarb works for athletes.

Scientists started experimenting with bicarb alkalosis, or sodium bicarbonate loading, in the 1930s, but as research has built and been refined, our understanding has improved. As an alkaline substance (with a high pH) bicarb consumption can lead to acute metabolic alkalosis in the blood, and NaHCO3 can act like a sponge to absorb the acidic H+ ions. Termed an extracellular buffer (found in the blood and interstitial fluid), bicarbonate can delay or reduce muscle acidosis that can give the burning sensation and fatigue of high intensity work. In turn this has led to a consensus that supplementation with bicarb can boost performance in high intensity activity (Lopes–Silva and Correia-Oliveira, 2023).

Can Sodium Bicarbonate Improve Hyrox Performance?

As a Hyrox event consists of eight different workout stations completed at high intensity, lactate production, and muscle acidosis are limiting factors for athletes (Brandt et al, 2025). Therefore by boosting muscle alkalosis, and the body’s capacity to buffer H+ ions, an appropriate bicarbonate dose can aid Hyrox race performance by reducing muscle acidity and delaying fatigue onset.

Whilst scientific studies haven’t yet tested sodium bicarbonate against placebo specifically in a Hyrox event, the wealth of research already conducted would seem very applicable to this type of event. With workout stations typically lasting from 1 to 6 minutes, bicarb has repeatedly been effective in improving performance on tasks of this duration (McNaughton et al, 2008, Saunders et al, 2014 and Bird et al, 1995).

In terms of Hyrox specificity, Brandt et al (2025) assessed the body’s acute physiological response to a simulated Hyrox event, and suggested lactate threshold to be a determining factor in predicting athlete performance. Probably the first specific study on the relatively new sport of Hyrox, this highlighted lactate accumulation as a key performance consideration, alongside oxygen consumption characteristics.

It was also observed that highest blood lactate was recorded in the final station, the wall balls. As Dalle et al (2021) demonstrated bicarb ‘s ability to aid sprint performance at the end of a longer endurance event, this appears effective in reducing the effects of lactic acid production during the closing stages of a Hyrox race. Bicarb has also been concluded to acutely enhance high intensity intermittent running (Grgic et al, 2021), which logically translates well to a Hyrox doubles race.

Sodium Bicarbonate for Endurance and High-Intensity Exercise – What the Science Says

Sodium bicarb supplementation gained significant attention during the Paris 2024 Olympics, with reports suggesting that many elite middle-distance runners were using bicarbonate systems to buffer muscle acidosis and delay fatigue.

The scientific evidence supporting sodium bicarbonate as a performance aid is particularly for high-intensity endurance exercise. An umbrella review of multiple meta-analyses found that bicarbonate supplementation consistently improves performance in events lasting approximately 45 seconds to 8 minutes, with benefits observed across cycling, running, rowing and swimming disciplines (Grgic et al., 2021). 

More specifically, a meta-analysis of cycling time-trial studies reported improvements in both mean power output and overall performance time following bicarbonate ingestion, highlighting its ability to help athletes sustain higher intensities when fatigue begins to build (Lopes-Silva et al., 2022). For endurance athletes, this buffering effect helps counter the accumulation of hydrogen ions associated with hard efforts, delaying the onset of muscular fatigue.

Research on muscular endurance also demonstrates meaningful benefits. A systematic review and meta-analysis by Grgic et al. (2020) found that sodium bicarbonate significantly improved muscular endurance performance, increasing the number of repetitions athletes could complete before reaching failure. Similar findings have been reported in resistance-training studies, where bicarbonate supplementation enhanced total training volume and maintained power output during repeated sets. These outcomes are particularly relevant for functional fitness athletes who must repeatedly produce force under fatigue, as improved buffering capacity can help preserve movement quality and output when muscles are under sustained stress (Grgic et al., 2020).

Research suggests bicarbonate is most effective when exercise involves repeated high-intensity efforts combined with incomplete recovery. This closely mirrors the demands of HYROX, where competitors alternate between running and challenging functional stations such as sled pushes, lunges, rowing and wall balls. By helping to manage exercise-induced acidosis, sodium bicarbonate may allow athletes to maintain a faster running pace, sustain higher work rates during stations and reduce the performance drop-off that often occurs in the latter stages of competition. Taken together, the current scientific literature indicates that bicarbonate supplementation can be a valuable tool for HYROX athletes seeking to improve both endurance and fatigue resistance during race-day efforts (Grgic et al., 2021; Grgic et al., 2020; Lopes-Silva et al., 2022).

How Much Sodium Bicarbonate Should You Take for Hyrox?

Bicarb Dosage recommendations

Sports science consensus suggests a dose of 0.3g of bicarb per kg of body weight provides an effective performance gain (Siegler et al, 2016). Some research trials found a smaller benefit associated with a smaller dose, for example 0.2g/kg, and this can be a useful way to trial bicarb and see how your body responds. As an example an 80kg athlete aiming for a full competition dose of 0.3g/kg would target 24g of sodium bicarbonate.

How long before Hyrox should you use Bicarb?

Meta-analysis of multiple studies ranging between 72 hours and 90 minutes prior to exercise have shown a performance benefit from bicarb supplements (Lino et al, 2021), but a window of 2 to 3 hours seems most well-supported (Grgic et al, 2020), and this can be influenced by the method of delivery of the bicarbonate.

There is also evidence that time topeak blood bicarbonate (HCO3− peak) varies between individuals, and also as an effect of undertaking a warm up prior to racing (Lassen et al, 2021). Great benefit was seen amongst athletes who followed a bicarb system personalised to them, so experimentation in training may allow athletes to work out the best time for them to consume bicarbonate.

VOOM Bicarb Charger delivers bicarbonate in enteric coated capsules, so the higher end of recommended time range is most effective, allowing time for the capsules to leave the stomach, reach the small intestine and release the bicarb for absorption into the blood. The advantage of this is the consumption is well clear of any warm up period, meaning one less thing to think about in the final hour or two before competing.

What Are the Risks and Side Effects of Bicarb?

While sodium bicarbonate is one of the most effective performance supplements available, gastrointestinal (GI) discomfort remains its most common drawback (Peart et al, 2012). Symptoms can include bloating, nausea, stomach cramps, belching and diarrhoea, particularly when large doses are consumed close to exercise. In one study using the standard performance-enhancing dose of 0.3 g/kg body weight, 91% of participants experienced diarrhoea, 64% reported bloating and thirst, and 45% experienced nausea (Kahle et al., 2013). 

Fortunately, several evidence-based strategies can help improve tolerance. Research suggests that consuming sodium bicarbonate alongside a carbohydrate-rich meal and allowing 2–3 hours before exercise can reduce GI symptoms while still achieving the desired increase in blood bicarbonate levels (Carr et al., 2011).

Sodium bicarbonate also contains a significant amount of sodium—approximately 27% by weight—meaning a typical ergogenic dose can exceed the recommended daily sodium intake in a single serving (Kahle et al., 2013). For this reason, athletes with hypertension, kidney disease, cardiovascular conditions, or those following medically prescribed low-sodium diets should consult a healthcare professional before using it. It’s also important for athletes to consider overall sodium intake if using electrolyte supplements which are typically designed to replenish sodium losses.

Splitting the dose into smaller servings, using delayed-release capsules, or choosing advanced delivery systems such as encapsulated bicarbonate products may also help minimise stomach discomfort while maintaining performance benefits. As with any race-day nutrition strategy, athletes should trial sodium bicarbonate during training rather than for the first time in competition to determine their individual tolerance and optimal dosing approach.

Should I use Sodium Bicarbonate for my next Hyrox?

Sodium bicarbonate is one of the most extensively researched performance supplements available and may offer a meaningful advantage for HYROX athletes by helping to delay fatigue during repeated high-intensity efforts. Athletes competing for personal bests, podium positions or qualification spots are likely to benefit most, particularly if they have already optimised the fundamentals of training, nutrition and hydration. 

However, it is not a magic bullet, and the potential 2-3% performance gains must be weighed against the risk of gastrointestinal discomfort and the practical challenges of dosing. For recreational competitors, first-time HYROX participants or anyone who experiences significant side effects during training, the benefits may not justify the hassle. As with any performance strategy, the key is to test thoroughly in training, refine your protocol and only use it on race day if you know it works for you.

References & Articles on Bicarb

Bird, S.R., Wiles, J. and Robbins, J. (1995). The effect of sodium bicarbonate ingestion on 1500-m racing time. Journal of Sports Sciences. 13(5). pp. 399–403.

Brandt, T., Ebel, C., Lebahn, C. and Schmidt, A. (2025). Acute physiological responses and performance determinants in Hyrox© – a new running-focused high intensity functional fitness trend. Frontiers in Physiology. 16. Article 1519240.

Brooks, G.A. (2020). Lactate as a fulcrum of metabolism. Redox Biology. 35. Article 101454.

Carr, A.J., Hopkins, W.G. and Gore, C.J. (2011). Effects of acute alkalosis and acidosis on performance: A meta-analysis. Sports Medicine. 41(10). pp. 801–814.

Dalle S, Koppo K, Hespel P. Sodium bicarbonate improves sprint performance in endurance cycling. J Sci Med Sport. 2021;24(3):301–6.

Douroudos, I.I., Fatouros, I.G., Gourgoulis, V., Jamurtas, A.Z., Tsitsios, T., Hatzinikolaou, A., Margonis, K. and Taxildaris, K. (2006). Dose-related effects of prolonged NaHCO₃ ingestion during high-intensity exercise. Medicine & Science in Sports & Exercise. 38(10). pp. 1746–1753.

Edge, J., Bishop, D. and Goodman, C. (2006). Effects of chronic NaHCO₃ ingestion during interval training on changes to muscle buffer capacity, metabolism, and short-term endurance performance. Journal of Applied Physiology. 101(3). pp. 918–925.

Grgic J, Rodriguez RF, Garofolini A, Saunders B, Bishop DJ, Schoenfeld BJ, Pedisic Z. Effects of sodium bicarbonate supplementation on muscular strength and endurance: a systematic review and meta-analysis. Sport Med. 2020;50:1361–75.

Higgins, M.F., James, R.S. and Price, M.J. (2013). The effects of sodium bicarbonate (NaHCO₃) ingestion on high-intensity cycling capacity. Journal of Sports Sciences. 31(9). pp. 972–981.

Kahle LE, Kelly PV, Eliot KA, Weiss EP. Acute sodium bicarbonate loading has negligible effects on resting and exercise blood pressure but causes gastrointestinal distress. Nutrition Research, 2013.

Lino RS, Lagares LS, Oliveira CVC, Queiroz CO, Pinto LLT, Almeida LAB, et al. Effect of sodium bicarbonate supplementation on two different performance indicators in sports: a systematic review with meta-analysis. Phys Act Nutr. 2021;25:7–15

Lopes-Silva JP, Correia-Oliveira CR. Acute effects of sodium bicarbonate ingestion on cycling time-trial performance: a systematic review and meta-analysis of randomized controlled trials. Eur J Sport Sci. 2023. Jun;23(6):943–954.

Lassen TAH, Lindstrøm L, Lønbro S, et al. Increased performance in elite runners following individualized timing of sodium bicarbonate supplementation. Int J Sport Nutr Exerc Metab. 2021;31(6):453–459

Maughan, R.J., Burke, L.M., Dvorak, J., Larson-Meyer, D.E., Peeling, P., Phillips, S.M., Rawson, E.S., Walsh, N.P., Garthe, I., Geyer, H., Meeusen, R., van Loon, L.J.C., Shirreffs, S.M., Spriet, L.L., Stuart, M., Vernec, A., Currell, K., Ali, V.M., Budgett, R.G.M., Ljungqvist, A., Mountjoy, M., Pitsiladis, Y.P., Soligard, T., Erdener, U. and Engebretsen, L. (2018). IOC consensus statement: dietary supplements and the high-performance athlete. British Journal of Sports Medicine. 52(7). pp. 439–455. 

McNaughton, L.R., Gough, L., Deb, S., Bentley, D. and Sparks, S.A. (2016). Recent developments in the use of sodium bicarbonate as an ergogenic aid. Current Sports Medicine Reports. 15(4). pp. 233–244.

McNaughton, L.R., Siegler, J. and Midgley, A. (2008). Ergogenic effects of sodium bicarbonate. Current Sports Medicine Reports. 7(4). pp. 230–236.

Peart, D.J., Siegler, J.C. and Vince, R.V. (2012). Practical recommendations for coaches and athletes: A meta-analysis of sodium bicarbonate use for athletic performance. Journal of Strength and Conditioning Research. 26(7). pp. 1975–1983.

Robergs, R.A., Ghiasvand, F. and Parker, D. (2004). Biochemistry of exercise-induced metabolic acidosis. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. 287(3). pp. R502–R516.

Saunders, B., Sale, C., Harris, R.C. and Sunderland, C. (2014). Sodium bicarbonate and high-intensity-cycling capacity: Variability in responses. International Journal of Sports Physiology and Performance. 9(4). pp. 627–632.

Siegler, J.C., Marshall, P.W.M., Bishop, D. et al. Mechanistic Insights into the Efficacy of Sodium Bicarbonate Supplementation to Improve Athletic Performance. Sports Med – Open 2, 41 (2016).