BICARBONATE SUPPLEMENTATION IMPROVES HIGH-INTENSITY ENDURANCE
Zinner, C., Wahl, P., Haegele, M., Behringer, M., Sperlich, B., & Mester, J. (2009). Is bicarbonate a performance enhancing drug? A paper presented at the 14th Annual Congress of the European College of Sport Science, Oslo, Norway, June 24-27.
This study determined the effects of bicarbonate on blood lactate accumulation, metabolism, and performance. To observe the effects of bicarbonate (HCO3), the aim was to exhaust the "normal" in-vitro buffer capacity by short all-out intervals. Male athletes (N = 8) performed two separate sessions each consisting of four 30-second sprints on a cycle ergometer. Between the sprints, Ss remained in a sedentary position on the cycle ergometer for five minutes. The sessions started with a warm-up of 10 minutes at an intensity of 1.5 Watt/kg. Ss ingested either 0.3 g/kg of sodium bicarbonate (NaHCO3) or 2 g of a placebo (calcium carbonate) diluted in 0.02 ml/kg of water over a 90-minute rest before the warm-up started. Arterialized capillary blood samples were taken from the hyperemized earlobe before ingestion, post-ingestion, after the warm-up, and during the rest periods between each bout.
Prior to ingestion, pH and [HCO3] did not differ between the two interventions. The pre- exercise pH and [HCO3] (post warm-up) were significantly increased after NaHCO3 ingestion compared to placebo. At the end of the exercise trials, the pH was significantly lower for the placebo condition. At the end of the tests, lactate values were significantly higher for the NaHCO3 condition than the placebo condition. Mean power showed significant differences between both conditions. During the first and the second bout, performances were similar for the conditions. Performances during the third and the fourth bouts were significantly lower in the placebo intervention.
Implication. Bicarbonate supplementation produced significantly higher mean power values during the latter third and fourth bouts in the exercise battery. Lactate is transported with H+ ions by monocarboxylate transporter proteins. Therefore, bicarbonate, which does not enter the muscle, increases the concentration gradient of H+ ions between the muscle and the blood causing a greater efflux of H+ ions out of the muscle accompanied by lactate into the blood. The supplementation seems not to increase only the "in vitro" buffer capacity, but also the "in vivo" buffer capacity, which is the ability of a cell to regulate pH. It is speculated that this increase improves the capability of muscle to maintain high-intensity performance longer.
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