Energy production via anaerobic glycolysis, which is particularly important for events lasting between 30 seconds and 15 minutes, increases the acidity inside the muscle cells and very soon after does the same to the blood. It is this increase in acidity within the muscle cells that is a major factor in producing fatigue in such events. If there was some way to reduce the acidity within the muscle cells, one could theoretically delay fatigue and thus continue exercising at a very high intensity for longer.
Sodium bicarbonate is an alkalising agent and therefore reduces the acidity of the blood (known as a buffering action). By buffering acidity in the blood, bicarbonate may be able to draw more of the acid produced within the muscle cells out into the blood and thus reduce the level of acidity within the muscle cells themselves. This could delay the onset of fatigue.
Who might benefit?
The specific athletes who might stand to benefit from bicarb supplementation will typically compete in events that last between one and seven minutes, i.e. 400 metres to 1500 metres running, 100 metres to 400 metres swimming, most rowing competitions, and many team sports with their repeated nature of high intensity exercise which stresses the anaerobic glycolysis system significantly and produces a lot of acidity.
A practical approach
Before using either bicarbonate, it is wise to check with the governing body of your sport that the substance is not contrary to doping regulations. The most important practical point is the need to experiment with the supplement during training. Typically, an 800 metre runner, may perform a time trial on a particular day after a couple of days of light training. A further couple of days later, after only more light training, he/she can repeat the time trial in a similar environment after bicarbonate supplementation. The exact protocol would be to ingest 0.3 grms of sodium bicarbonate per kg body weight approximately one to two hours before the time trial. That is, for a 66kg runner, consume 20 grms of sodium bicarbonate (about four teaspoons) and, yes, the commonly found bicarb of soda is exactly the substance needed. This experimenting, if repeated several times, should reveal whether bicarb supplementation is likely to produce any benefit and whether the athlete concerned is susceptible to any side effects.
It is likely that large individual differences do exist as far as response to supplementation is concerned. It has been suggested that the more highly trained athletes are less likely to benefit from it because their body's natural buffering systems are already so well developed, but so far this is just speculation. It has also been shown that sprinters build up more acidity within their muscles than endurance runners in response to the same exercise, and so may be more likely to benefit from the buffering effect. From the scientific research, it appears that the size of the dose is quite important, and that taking only 0.2 grms per kg is less likely to be beneficial than 0.3 grms per kg, although no evidence exists suggesting that an even greater dose is better still.
Side effects
As for the side-effects, these may take the form of pain, cramping, diarrhoea or a feeling of being bloated. Drinking up to a litre of water with the dose is often effective and should be carried out as standard. Breaking up the bicarbonate dose into, say, four equal portions taken over the course of an hour may also help.
There are potential side effects to taking higher than normal levels of Sodium Bicarbonate so consult with your doctor first.