Elevation of anions in exercise-induced acidosis: a study by ion-exchange chromatography/mass spectrometry

Acidosis is a major factor that determines the upper limit of exercise endurance. We have previously shown that anions usually associated with intermediary metabolism are elevated in critically ill patients with metabolic acidosis and contribute significantly to acidosis generation. This study was to determine whether volunteers with normal metabolism would exhibit similar elevations in anions associated with intermediate metabolism when exposed to a short-term physiological stress leading to a brief lactic acidosis. Physiological stress was induced on five healthy male subjects by means of a ramped exercise protocol. Blood was obtained immediately prior to and post-exercise, plasma ultrafiltrate was prepared and analysed immediately both by enzyme assay and liquid chromatography coupled to electrospray-mass spectrometry (LC/ESI-MS). Metabolic acidosis concomitant with a significant increase in blood lactate occurred in each subject, but in addition, anions normally associated with intermediate metabolism were significantly elevated after exercise. The contribution of these anions to generating an acidosis, and thus potentially limiting the extent of exercise, has never been acknowledged.