FLUID, ELECTROLYTE, AND ACID-BASE RESPONSES TO EXERCISE IN RACEHORSES

During both high-intensity and short-distance exercise, the high rate of expended energy is met by anaerobic oxidation of glucose to lactic acid; this is the main cause of metabolic acidosis observed during rac ing. In addition, plasma volume decreases because water moves from the vasculature to the intracellular and interstitial spaces at the onset of intense exercise. These fluid shifts, together with active ion-exc hange between blood and tissue, cause marked changes in electrolyte co ncentrations. This article reviews the mechanisms of acid-base disturb ances, fluid shifts, and electrolyte changes, and discusses related ar eas such as buffer capacity, lactic acid distribution, and the effects of training. The influences of health, dietary cation-anion balance, supplements, and medication such as creatine, sodium bicarbonate, and furosemide are emphasized.