Buffering Your Blood

Blood pH refers to the acidity or alkalinity of our blood. Exercising at high intensity, muscles in the body produce a large amount of lactic acid through anaerobic respiration. In fact, exercising at maximal intensity (e.g. sprinting) for 30 seconds will significantly change the pH inside muscle cells. At a lower blood pH (high acidity due to lactic acid accumulation), the performance of enzymes and muscles will decline.

The body has its own natural buffers to regulate the pH inside anaerobically respiring muscle cells. Bicarbonate ions are once such buffer. From the blood, these ions enter the busy muscle cells to neutralise the effect of lactic acid accumulation.

For years, sports coaches have experimented with bicarbonate supplements. Experiments conducted on middle-distance runners show that athletes ran an average of 2.9 seconds faster when their blood pH has been raised through the ingestion of bicarbonate drinks. Apart from bicarbonate, sodium citrate has also been tried. The results were similar. Nowadays, citrate has virtually replaced bicarbonate as a buffering agent as bicarbonate often causes stomach upset.

Theoretically, buffering of blood pH would only benefit anaerobic activity where lactic acid is produced. In low intensity aerobic activity where carbohydrates are completely metablised to carbon dioxide and water, buffering would not yield the same results.

However, experiments done on cyclists doing 30km, have shown that those who consumed buffering drinks rode significantly faster than those who didn’t. This shows that consuming drinks that contain bicarbonate or citrate will benefit athletes regardless of whether they engage in high intensity, short workouts or low intensity, long workouts. Of course, the former benefits more.

Where does one get buffering drinks? One convenient source would be isotonic drinks. Apart from electrolytes like potassium, these drinks also contain small amounts of buffering agents like citrate. Such amounts are most suitable for low to medium intensity exercises. For high intensity exercises, 0.5g sodium citrate per kg body weight is required.

© Chan Joon Yee

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