Soda Loading (Bicarbonate Loading, Buffer Boosting) for High Intensity Anaerobic Endurance

Posted on 07 May 2012 17:30

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During high intensity anaerobic events, the muscles fatigue and energy supply is compromised because of the buildup of lactic acid from glycolysis. Athletes in high intensity events that last 2 to 10 minutes, such as a 400 to 800 or 1500 meter running races or middle distance swimming races sometimes use soda loading in an attempt to neutralize the lactic acid that accumulates in the blood. Depending on interpretation of the research, some experts suggest that the benefit is limited to events of 1 to 7 minute duration. Soda loading is also called buffer boosting or bicarbonate loading. It is also called, more rarely, soda doping or simply acid buffering.

The theory is that since bicarbonate appears naturally in the blood and is the body's primary buffering system, having the important role (among others) of buffering lactic acid, loading the system by ingesting large amounts of baking soda (sodium bicarbonate) in advance of the event should increase the amount of bicarbonate in the blood, making it more alkaline and therefore increasing anaerobic endurance by limiting lactic acid buildup and/or hydrogen ions (H+). The accumulation of both of these is believed to inhibit muscle contraction and metabolic processes, resulting in fatigue and the inability to continue working at the same intensity.

The mechanism by which soda loading is thought to work has to do with metabolic alkalosis (see alkalosis definition). Normally, the blood's acidity is tightly controlled so that the pH of the blood plasma remains between 7.35 to 7.45, which is known as the acid-base balance. Sometimes, the blood can become too acid, so that the pH falls below 7.35. For instance, this may occur in diabetics because of ketoacidosis. This may also happen during starvation, or in chronic alcoholism. Another cause is lactic acidosis (see acidosis definition), which can occur after cardiac, hemorrhagic, or septic events, as well as through systemic disorders or from drug side effects. As well, the loss of bicarbonate through diarrhea or through fistula drainage can cause hyperchloremic metabolic acidosis, which occurs because of the loss of large amounts of bicarbonate containing fluids from the gut. Other mechanisms, such as renal failure, are also possible.

Although the primary treatment of any metabolic acidosis is to remove the underlying cause of the acidosis, the excess acid can be directly addressed by the administration of an alkaline agent, which is primarily bicarbonate. Sodium bicarbonate might be given as an IV and it is separated in the blood and the bicarbonate acts as a buffer against the access acid, bringing up the pH.

The opposite of metabolic acidosis is metabolic alkalosis. This occurs when the amount of plasma bicarbonate increases enough to cause an increase in pH to beyond 7.45. Although there are many possible causes for this, it is sometimes induced by the over-consumption of antacids for the treatment of acid indigestion or GERD. The most common of these are sodium bicarbonate (baking soda) containing products, such as Alla-Seltzer. Although rare, the chronic over-use of these products can lead to an induced alkalosis. The intent of soda loading is to artificially induce this condition, which is caused unintentionally by excess antacid use. Large staggered doses are necessary to introduce enough bicarbonate to cause an increase in plasma buffering capacity.

The reason that the buffering capacity of the blood is important has to do with how energy is generated during anaerobic performance. During the first 8 to 10 seconds, the primary fuel for muscle contraction is stored ATP. However, later and up to the first two minutes or so, the energy is supplied primarily by anaerboic glycolysis. The end product of this is lactate, which diffuses into the blood. This is also accompanied by an increase in the amount of hydrogen ions. The result is that during intense exercise the pH of the blood can drop to as low as 6.9, and even lower in the muscle. At this level of pH, or acidity, the activity of phosphoructokinase, which is the key enzyme in glycolosis, greatly decreases, meaning that the further production of energy from anaerobic metabolism is restricted. The acidity also affects calcium channels, thereby also impairing muscle fiber contraction. This is one reason why the amount of work that can be maintained at relatively high intensities is limited. Since the increased acidity in the blood and muscles is the culprit, the idea of increasing the buffering capacity of the blood by artificially inducing alkalosis was hit upon in the 1930's, leading to the concept of using buffering agents such as sodium bicarbonate or sodium citrate. If this was done, it was reasoned, the acidity of the blood might be somewhat diminished leading to an increase in anaerobic performance. This concept was presented and confirmed experimentally by Dennig and Dill1.

Therefore, the practice of soda loading is not new; it has been used for at least 70 years and research into the question of whether the blood acid buildup (decreased pH) of the blood during high-intensity anaerobic exercise could be attenuated have been going on since that time. The effect of increasing bicarbonate is limited to the blood plasma, since the bicarbonate cannot enter the muscles. The concentration of bicarbonate in the muscles will remain unchanged and the accumulation of acid in the muscles inhibits muscle fiber contraction. However, the increased gradient of hydrogen ion concentration across the cell membrane accelerates the diffusion of hydrogen ions out of the cell, thus reducing the acidity in the muscle cell. So, in effect, the increased bicarbonate in the blood reduces the acid buildup in the muscles. Although this has been confirmed, whether soda loading actually does lead to increased performance is still questionable.

Sodium citrate or sodium lactate loading is also used and widely advocated. Doses of 0.3 grams of sodium bicarbonate, 0.3 to 0.5g sodium citrate, or 0.4g of sodium lactate per kilogram of body weight is ingested 1 to 2 hours before the event. These doses should elevate blood pH for up to 3 hours after ingestion, peaking at 1 to 2 hours.

There is no reason, whatsoever, that soda loading will help a maximum strength athlete performance of a 1RM as lactic acid buildup is not a factor in the time frame involved. However, the practice has found its way into bodybuilding in an attempt to increase the volume of resistance training performed. Since anaerobic glycolosis continues to provide a small amount fuel during later stages of work, which is primarily aerobic, the question has also been raised as to whether soda loading could increase aerobic performance, but there have been no indications that this is true.

There is some evidence that this practice provides small results for anaerobic athletes who perform at high intensities lasting for around one minute and not more than two, as may be useful for an elite athlete, where the gain of 1 second can be significant. Around half of studies performed showed a beneficial effect, ranging from 2 to 62%. The very good results tend to occur only in the earlier studies, most likely because these studies were not well designed. Not all research studies have found a benefit, however, and the existence of an actual ergogenic effect is controversial. The benefit varies depending on the actual intensity of the exercise. It seems likely that any actual benefit is individual, causing some to speculate that certain people may be "non-responders". The idea of the non-responder is often used to explain inconsistent results with ergogenic aids, however, and should be met with skepticism. Although the amount of research is vast, the answer as to whether it works is still "maybe."

Doping Status

Soda loading is not banned at this time by any athletic organizations but it is likely to be banned in the near future as it clearly goes against most doping regulations. It is certainly in violation of the USOC/IOC doping law which prohibits the "administration or use by a competing athlete of any foreign substance to the body or of any physiological substance taken in abnormal quantity or taken by an abnormal route of entry into the body with the sole intention of increasing in an artificial and unfair manner his/her performance in competition." Here, sodium bicarbonate loading would be the use of a "physiological substance" in "abnormal amounts" and this clearly qualifies it as a banned practice. According to the law, although it isn't explicitly banned by the Olympic committees, it is illegal, but is just not tested for.

However, the use of sodium bicarbonate for the treatment of an upset stomach or to treat metabolic acidosis is perfectly reasonable. Small doses would be used for these treatments and very large doses are used for bicarbonate loading. Should it be banned, excess bicarbonate can be easily detected in the urine.

The practice is banned in dog and horse races.3,2

Side Effects of Soda Loading

The side effects of soda loading may well offset any small benefit you get. As early as one hour and as late as 3 hours after ingestion, urgent diarrhea will occur in about half of users. Bloating and gastrointestinal cramping is also likely, as well as nausea and dizziness. There is also a significant gas development. The gastrointestinal symptoms are most likely due to a large amount of water being drawn into the intestines to counter the sodium load imposed on the gut.4,3 Consuming large volumes of water, as desired, may help to minimize these symptoms. It is also suggested that the dosage of 300mg/kg of body mass be divided into five equal parts over a one to two hour period.5

Metabolic alkalosis can occur when the blood reaches a very high pH and a high plasma bicarbonate concentration. A loss of H+ or a gain of bicarbonate both can cause this condition, and the intent of soda loading is both. Excessive alkali ingestion from antacids containing bicarbonate or from using sodium bicarbonate during cardiopulmonary resuscitation have been known to cause metabolic alkalosis. Very large doses, especially ongoing ones, could be dangerous in this regard, although any harmful effect should be ameliorated by ceasing the loading of bicarbonate. Muscle weakness and spasms, vomiting, irritability, and even convulsions could occur, although unlikely.

There is no knowledge of the long-terms effect of this practice.4,3

General Statements about Bicarbonate Loading

  • Optimal dosage seems to be around 300mg/kg body weight.
  • Higher doses, although they may be more effective in some cases, usually result in gastrointestinal symptoms
  • Bicarbonate loading does not enhance single bout performances of high-intensity exercise of less that 50-second duration (a maximal lift, for instance)
  • Bicarbonate loading does not seem to help with single bouts of submaximal intensity
  • Bicarbonate loading may enhance performance during short-duration high-intensity exercise, if the exercise is sufficient to challenge the bicarbonate buffering system.4
  • Although many studies have been performed to measure the effect of the soda loading on
1. Faff, J. "Can Work Capacity Be Improved by Inducing Pre-Exercise Alkalosis?" Biology of Sport 10.3 (1993): 127-40.
2. Meltzer, Shelly, and Cecily Fuller. The Complete Book of Sports Nutrition: A Practical Guide to Eating for Sport. London: New Holland, 2005. 103.
3. Noakes, Timothy. Lore of Running. Champaign, IL: Leisure, 1991.726-728.
4. Bahrke, Michael S., and Charles Yesalis. Performance-enhancing Substances in Sport and Exercise. Champaign, IL: Human Kinetics, 2002. 198-203.
5. Kenney, W. Larry., Jack H. Wilmore, David L. Costill, and Jack H. Wilmore. Physiology of Sport and Exercise. Champaign, IL: Human Kinetics, 2012.

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This page created 07 May 2012 17:30
Last updated 15 Feb 2017 21:22

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