How Muscle Fatigue Works
During short term (anaerobic) exercise, ATP and creatine phosphate (CP) are used up within the first 7 seconds of training. This signals the metabolism of glycogen to produce energy for your body. This process is known as glycolysis. During glycolysis, glycogen (muscle sugar) is broken down to produce more CP. The breakdown of CP releases energy, which catalyzes a reaction to produce ATP. The production of more ATP allows movement of the muscle to continue. Lactic acid is a product of glycolysis created by the breaking down of pyruvate.
Lactic acid is then disassociated to produce lactate. When lactic acid (C3H6O3) releases a hydrogen ion (H+), the remaining compound binds to a sodium ion (Na+) or a potassium ion (K+) to form a salt. It is this salt that is lactate. Now the cell contains a lactate compound and a free H+ for each compound of lactic acid that is produced. It is this increase in cellular H+ that causes the pH to decrease, becoming more acidic. The acid in the muscle causes the fibers' calcium-binding capacity to decrease, thus limiting muscle contraction. This is the cause of muscle fatigue.
Some of the lactate seeps out of the cell into the bloodstream where it is sent to the liver to be used to synthesize glucose. The remainder of the lactate must be eliminated in the cell. Oxygen and cellular lactic acid act together to resynthesize ATP via anaerobic metabolism.
How Can I Prolong Muscle Fatigue?
The question many athletes want answered is how can I prolong my muscle fatigue? Theoretically, if you can decrease the amount of acid build-up produced in the muscles, then you can delay the onset of muscle fatigue. One method of decreasing acid build-up is by buffering it with a base compound.
The most significant buffer compound found in human blood is carbonate. Other buffering agents are also present, including proteins and organic acids, but they are present in much smaller concentrations. When the pH in the blood falls due to the increase of H+, the carbonate-carbonate acid equilibrium shifts toward more acidic. At this same time the carbonic acid loses water (H20) to become CO2. The CO2 produced is lost in the lungs through exhalation.
When blood pH increases, more carbonate is formed and more CO2 is taken from the lungs to be used in the blood for conversion to carbonic acid. Acidosis is a disturbance in the blood buffer system resulting in a pH as low as 7.1, where the normal blood pH is 7.4. The normal treatment of acidosis is an injection of sodium carbonate. This process sparked the idea that the consumption of sodium carbonate could prolong acid build-up causing muscle fatigue.
Some research has shown that the consumption of sodium carbonate (an alkalizing agent) helps to buffer the lactic acid concentration in the bloodstream. The decrease in blood acidity would in turn allow the acid within the cells to enter the blood stream via the concentration gradient. carbonate is not able to enter the cells; therefore it must act in the bloodstream.
In an attempt to kick start the body's natural carbonate process, some sprinters will try hyperventilating shortly before a race with the hope that it will help reduce acid build-up. This increases the pH of the blood slightly, making it better able to deal with the short-term build-up of lactate and acid during the sprint.
According to Mc Naughton et al. (1997), research found that the consumption of sodium carbonate in athletes competing in short events (1-7 minutes) improved their performance by 1-2%. This means that if you were Kevin Herlihy of the UCSB men's swim team and you increased your performance in the 200m freestyle (1:40.81) by 2%, you could potentially decrease your time by about 2.02 seconds.
The effective dose of sodium carbonate is 135mg/lb of body weight (0.3g/kg of body weight). Doses above 20gm have been shown to cause vomiting and diarrhea. Athletes who have performed in the experiments (Mc Naughton et al. (1997)) took the carbonate substance 60-90 minutes before exercising.
Not everyone reacts the same to supplementation, and it is for this reason that the research on sodium carbonate is conflicting. For every study done that gives positive results there is another giving the opposite. It is for this reason that experimentation is done. If you are able to stomach the sodium carbonate, you just might get the results you are looking for. carbonate supplementation would not be advantageous for endurance athletes, since they do not accumulate as much lactic acid in their muscles as do sprinters.
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Sodium carbonate is incompatible with acids, acid salts, ammonium chloride, lime water, ephedrine hydrochloride, and iron chloride. It is used to treat acidosis (e.g., in renal failure). Orally it is used as an antacid, although its effectiveness for this purpose is questionable. Externally, it is used as a mild alkaline wash. It is also used as a component in many laboratory reagents, such as various buffers, microbiologic media, and control materials.
Solutions containing sodium ions should be used with great care, if at all, in people with congestive heart failure, severe renal insufficiency and in clinical states in which there exists edema with sodium retention. In people with diminished renal function, administration of solutions containing sodium ions may result in sodium retention.
The intravenous administration of these solutions can cause fluid and/or solute overloading resulting in dilution of serum electrolyte concentrations, over hydration, congested states or pulmonary edema.
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Voet, D., Voet, J., Pratt, C. (1999). Fundamentals of Biochemistry. p. 37, 667.
Mc Naughton, L.R., Dalton, B, Tarr, J., Buck, D. (1997). Neutralize Acid to Enhance Performance. Sportssciences Training & Technology. http://www.sportssci.org/traintech/buffer/lrm.htm
Williams, Alun. Sodium carbonate: Research suggests it may boost performance in short events, but it can have nauseating side effects. http://pponline.co.uk/encyc/0086.htm