Every few months, a chart makes the rounds showing the race to 100 million users. ChatGPT got there in two months. TikTok took nine. Instagram needed more than two years. A new innovation might take the crown next. The point of the chart is that innovations do not spread at the same speed. Some simmer for years. Others go from niche to everywhere before you notice.
Running has its own version of that race. Super shoes redefined how we train and race. Double-threshold work, once the domain of a few Scandinavian coaches, has spread to elite groups everywhere. But the innovation winning the race to ubiquity right now is stranger than any of them: sodium bicarbonate (aka baking soda).
A decade ago, bicarb was a lab curiosity or the private gamble of a few elites willing to risk their gut for a fraction of a percent. Today, you cannot watch a championship 800 without seeing athletes slurping down a bicarb mixture in the warmup area. Something changed. The question is whether the science justifies the hype, or whether this is just the supplement of the moment.
Here is what the evidence actually says.
The renaissance of an “old school” supplement
The science is not new. Bicarb was first studied in the early twentieth century. By the 1980s, its performance effect was well established, established enough that WADA once considered classifying it as a “restricted technique.” They dropped the idea for the obvious reason: you cannot ban something sitting in every kitchen in the world.
Then, through the 1990s and 2000s, the practice mostly died off. The reason was the gut. Swallowing a large dose of baking soda was a deal with the devil: a possible sliver of performance in exchange for a real chance of diarrhea, bloating, and vomiting. Bicarbonate meeting hydrochloric acid in your stomach produces a flood of CO2, and the gas has to go somewhere.
Bicarb has had a new wave of adoption among distance runners over the last several years. New delivery systems protect bicarb from stomach acid and allow it to pass into the intestine, where it is absorbed without side effects. Maurten drove the shift with a hydrogel that wraps thousands of bicarb micro-pills in a yogurt-like matrix.
The newest and more cost-effective player in this space, Bicarb 3.0, builds directly on this idea by adding another line of defense to help shuttle the baking soda through the stomach without any reactions. They have built their beadlets with an acid-resistant gel and then wrapped the bicarbonate core in a calcium carbonate shell that acts as a protective buffer against stomach acid. To learn more about this product, check out this episode of The Running Effect.
The physiology of fatigue: re-thinking lactate and acidity
To understand why bicarb works, you have to drop the “lactic acid” story most runners still carry around.
When you run faster than threshold, your muscles demand energy faster than the aerobic system can deliver. To cover the gap, you lean hard on glycolysis, the fast, non-oxidative pathway. That pathway produces lactate and hydrogen ions.
Lactate is not the villain. It is fuel. Your body recycles it for more energy. The actual cause of that heavy, burning sensation is the buildup of hydrogen ions, which drop the pH inside your muscle. That state is acidosis, and it is what wrecks you. Low pH jams key enzymes and degrades the muscle’s ability to contract. It is why runners “rig” at the end of a race: the stride shortens and stiffens because the acid is getting in the way of optimal movement.
How bicarb steps in
Sodium bicarbonate is a base. It neutralizes acid. Once absorbed through the intestine, it’s transported into the circulatory system, raising blood pH and bicarbonate concentration. That is extracellular alkalosis: basic blood surrounding acidic muscle.
With alkaline blood on one side and acidic muscle on the other, you create a steep chemical gradient, and that gradient pulls hydrogen ions and lactate out of the working muscle and into the bloodstream.
Think of bicarb as an acid sink. It does not stop acidosis. It clears acid from the muscle faster, so severe intramuscular acidosis builds up more slowly. Hold the muscle’s pH in a workable range for a few extra seconds, and it keeps producing energy at a high rate for a little longer. In a race decided by seconds, that is the difference maker.
Bicarb’s sweet spot for efficacy
Bicarb is not a blanket performance aid. The strongest evidence puts its benefit in high-intensity efforts lasting roughly 30 seconds to 12 minutes. That is exactly the window where glycolysis dominates, and the acid-base disturbance is most severe.
For runners, that maps cleanly onto the 400, 800, 1500, and arguably up to the 3000m. The classic trials, small and now decades old, are consistent:
400m: a study of trained 400m runners found bicarb improved times by about 1.5 seconds.
800m: research on varsity track athletes showed a 2.9-second improvement.
1500m: a study of 12 distance runners reported roughly a 3-second gain.
Across multiple sports and studies involving hundreds of participants, the International Society for Sports Nutrition published a position paper that anchored most improvements to bicarb in the 1-2% range. Although that sounds small, it could easily be the difference between a gold medal and finishing off the podium in a middle-distance race.
One caveat that holds across every legal performance supplement, not just this one: the more elite you are, the thinner the margin. The gains shrink as you get closer to the front. They rarely disappear, but I would not expect a world-class 800m runner to find three seconds from bicarb alone.
That being said, in recent months, two notable records have been broken with bicarb assistance. Last week, Josh Kerr broke the mile world record and endorsed bicarb as a part of his pre-race repertoire. In April, Simeon Birnbaum broke the NCAA record in the 1500 while using Bicarb 3.0.
The verdict on long races
With all the buzz, you might be tempted to load up before your next marathon. Before doing that, I would weigh two things: what the science shows and what the world's best runners are actually doing.
The data thins out fast beyond middle-distance races, though there is a signal at the long end. A 2024 study found that bicarb improved 40km cycling time-trial performance by 1.4%, suggesting some benefit in long, sustained work lasting near an hour. But for continuous running from the 5K to the marathon, the case weakens. As the distance grows, the physiology shifts. These races are run almost exclusively on the aerobic energy system, so the acid load in your muscles stays comparatively low, and therefore there is much less for bicarb to buffer.
Considering the scientific evidence alone, I used to think the risk outweighed the reward, and if you have a sensitive stomach, I still think it does. But there are numerous anecdotal reports of elite athletes raving about bicarb use in longer events.
There are a few plausible mechanisms: greater tolerance to late-race surges and better preservation of muscle function as fatigue builds. None of this has been rigorously tested. But elite athletics always moves faster than the literature. Whether bicarb proves itself over longer distances remains an open question, and it's a corner of the science I expect to advance quickly over the next few years.
Protocol: dose and timing
Dose: The effective dose is 0.2-0.3 g/kg body mass. Going higher rarely adds benefit and reliably worsens GI side effects. Start at the low end, 0.2 g/kg, in training, and see how your gut handles it.
Timing and co-ingestion. The standard window is 60 to 180 minutes before the race. The single best way to protect your gut is to take the dose with a carbohydrate-rich meal. If you go that route, aim for 2 to 2.5 hours out.
One rule overrides all of this: never test bicarb for the first time on race day. Trial your protocol in training, at race-effort sessions, and judge it from there.
My overall recommendation: There are plenty of supplements that overpromise. Bicarb is not one of them. The effect is real, the mechanism is sound, and it’s trickling down from the top of the sport for a reason. If you race the 800 or 1,500 meters, the supporting evidence is strong. Longer distances are a different call. This is really the bleeding edge. The science is thin, and the GI risk climbs the longer you’re out there. If you have an iron stomach and you want to experiment, you might find a marginal gain that the literature hasn’t caught up with yet. You could be early to something real, but the jury isn’t out. Proceed at your own risk.
Author’s Note [7/23 at 1:30 pm]: After a few conversations with coaching colleagues, I wanted to share one additional perspective that’s worth knowing. A single bicarb dose delivers a large sodium load, roughly 5,000 mg in one sitting, more than double the FDA’s recommended daily limit. For a healthy adult, the body can manage that as a one-off, but I would be more cautious about recommending this supplement blindly to young athletes. If I were coaching a young runner, I would reach for the low-hanging fruit first. Focus on the gains you can get from better training and recovery first. The supplement will still be there when you have earned the ability to look to the last 1%.
Alex, any thoughts on the topical preparations of bicarb in terms of effectiveness and side effects?
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