SODIUM-BICARBONATE INGESTION DOES NOT ATTENUATE THE VO2 SLOW COMPONENT DURING CONSTANT-LOAD EXERCISE

We examined the effects of sodium bicarbonate ingestion on the (V) ove r dot O-2 slow component during constant-load exercise. Twelve physica lly active mal es performed two 30-min cycling trials at an intensity above the lactate threshold. Subjects ingested either sodium bicarbona te (BIG) or placebo (PLC) in a randomized, counterbalanced order. Arte rialized capillary blood samples were analyzed for pH, bicarbonate con centration ([HCO3-]). and lactate concentration ([La]). Expired gas sa mples were analyzed for oxygen consumption ((V) over dot O-2). The (V) over dot O-2 slow component was defined as the change in (V) over dot O-2 from Minutes 3 and 4 to Minutes 28 and 29. Values for pH and [HCO 3-] were significantly higher for BIC compared to PLC. There was no si gnificant difference in [La] between conditions. For both conditions t here was a significant time effect for (V) over dot O-2 during exercis e; however, no significant difference was observed between BIC and PLC . While extracellular acid-base measures were altered during the BIC t rial, sodium bicarbonate ingestion did not attenuate the (V) over dot O-2 slow component during constant-load exercise.